1
Chapter - 1........................................................................................................................... 3
Introduction to Computer............................................................................................ 3
Computer................................................................................................................... 3
Power supply ............................................................................................................. 5
Video display controller ........................................................................................... 5
Removable media devices......................................................................................... 5
Secondary storage ..................................................................................................... 6
Sound card................................................................................................................. 6
Other peripherals...................................................................................................... 6
Generations of Computers ....................................................................................... 7
The Five Generations of Computers ....................................................................... 7
First Generation - 1940-1956: Vacuum Tubes ....................................................... 8
Second Generation - 1956-1963: Transistors ......................................................... 8
Third Generation - 1964-1971: Integrated Circuits .............................................. 9
Fourth Generation - 1971-Present: Microprocessors............................................ 9
Fifth Generation - Present and Beyond: Artificial Intelligence.......................... 10
Chapter – 2........................................................................................................................ 13
Computer Hardware .................................................................................................. 13
Part of a P.C. ........................................................................................................... 14
Case .......................................................................................................................... 14
Power Supply........................................................................................................... 15
Mother Board.......................................................................................................... 18
Accounting to Power Supply.................................................................................. 21
Chapter – 3........................................................................................................................ 38
Expansion Slots ........................................................................................................... 38
Micro Channel Architecture.................................................................................. 38
ISA Expansion Slots................................................................................................ 39
AGP Expansion Slots.............................................................................................. 41
RAM Slots................................................................................................................ 44
Chapter – 4........................................................................................................................ 47
Memory........................................................................................................................ 47
Two Types of Memory............................................................................................ 47
ROM (BIOS)............................................................................................................ 48
RAM (Random Access Memory)........................................................................... 50
DRAM (Dynamic) ................................................................................................... 50
SRAM (Static RAM)............................................................................................... 51
Dynamic Random Access Memory........................................................................ 51
Chapter – 5........................................................................................................................ 68
System Buses................................................................................................................ 68
Three types of bus ................................................................................................... 69
CPU (Central Processing Unit).............................................................................. 69
CPU Unit.................................................................................................................. 70
Chapter - 6......................................................................................................................... 75
Monitor ........................................................................................................................ 75
Inside CRT Displays ............................................................................................... 75
Diagram of Monochrome CRT.............................................................................. 76
2
Chapter - 7......................................................................................................................... 77
Printers........................................................................................................................ 77
Printers..................................................................................................................... 77
Image Formation Method ...................................................................................... 77
Fully Formed Character Printers.......................................................................... 77
Printing Mechanism................................................................................................ 78
Daisy Wheel Printer................................................................................................ 80
Chain Printer........................................................................................................... 81
Drum Printers ......................................................................................................... 82
Dot-Matrix Printers ................................................................................................ 83
Color Dot-Matrix Printers ..................................................................................... 84
Chapter - 8......................................................................................................................... 92
Assembling a PC ......................................................................................................... 92
Material Required................................................................................................... 92
Mainframes............................................................................................................ 101
Features.................................................................................................................. 103
Program execution................................................................................................ 103
Interrupts............................................................................................................... 104
Protected mode and supervisor mode................................................................. 104
Memory management........................................................................................... 105
Security .................................................................................................................. 110
Microsoft Windows............................................................................................... 111
Linux/Unix............................................................................................................. 112
Unix and unix-like operating systems ................................................................. 116
Mac OS X............................................................................................................... 117
Hobby development .............................................................................................. 118
Operating Software Installation .......................................................................... 123
What can be Upgrade? ......................................................................................... 124
Microsoft................................................................................................................ 126
Chapter - 9....................................................................................................................... 128
Windows shortcut Key ............................................................................................. 128
Windows shortcut key .......................................................................................... 128
XP Run Commands .............................................................................................. 132
Chapter-10....................................................................................................................... 142
Some Sort Form ........................................................................................................ 142
3
Chapter - 1
Introduction to Computer
Computer
C: - Common
O: - Operating
M: - Machine
P: - Particular
U: - Useful
T: - Trading/Training
E: - Education
R: - Research
A personal computer is made up of multiple physical components of computer
hardware, upon which can be installed an operating system and a multitude of software
to perform the operator's desired functions.
Hardware of a modern Personal Computer.
1. Monitor
2. Motherboard
3. CPU
4. RAM Memory
5. Expansion card
6. Power supply
7. Optical disc drive
8. Hard Disk
9. Keyboard
10. Mouse
4
Inside a custom computer.
Though a PC comes in many different forms, a typical personal computer consists of a
case or chassis in a tower shape (desktop) and the following parts:
The motherboard is the main component inside the case. It is a large rectangular board
with integrated circuitry that connects the rest of the parts of the computer including the
CPU, the RAM, the disk drives (CD, DVD, hard disk, or any others) as well as any
peripherals connected via the ports or the expansion slots. Computer Hardware course is
very important for the future because they are now essential in business.
Components directly attached to the motherboard include:
The central processing unit (CPU) performs most of the calculations which
enable a computer to function, and is sometimes referred to as the "brain" of the
computer. It is usually cooled by a heat sink and fan.
The chip set mediates communication between the CPU and the other
components of the system, including main memory.
RAM Stores all running processes (applications) and the current running OS.
RAM Stands for Random Access Memory
The BIOS includes boot firmware and power management. The Basic Input
Output System tasks are handled by operating system drivers.
Internal Buses connect the CPU to various internal components and to expansion
cards for graphics and sound.
o Current
The north bridge memory controller, for RAM and PCI Express
PCI Express, for expansion cards such as graphics and physics
processors, and high-end network interfaces
PCI, for other expansion cards
SATA, for disk drives
o Obsolete
ATA (superseded by SATA)
AGP (superseded by PCI Express)
VLB VESA Local Bus (superseded by AGP)
ISA (expansion card slot format obsolete in PCs, but still used in
industrial computers)
External Bus Controllers support ports for external peripherals. These ports may
be controlled directly by the south bridge I/O controller or based on expansion
cards attached to the motherboard through the PCI bus.
o USB
o FireWire
o SATA
o SCSI
5
Power supply
A power supply unit (PSU) is the component that supplies power to the other components
in a computer. More specifically, a power supply unit is typically designed to convert
general-purpose alternating current (AC) electric power from the mains (100-127V in
North America, parts of South America, Japan, and Taiwan; 220-240V in most of the rest
of the world) to usable low-voltage DC power for the internal components of the
computer. Some power supplies have a switch to change between 230 V and 115 V.
Other models have automatic sensors that switch input voltage automatically, or are able
to accept any voltage between those limits. It’s divert high voltage into low voltage
Video display controller
Produces the output for the computer monitor. This will either be built into the
motherboard or attached in its own separate slot (PCI, PCI-E, PCI-E 2.0, or AGP), in the
form of a graphics card.
Removable media devices
CD (compact disc) - the most common type of removable media, suitable for
music and data.
o CD-ROM Drive - a device used for reading data from a CD.
o CD Writer - a device used for both reading and writing data to and from a
CD.
DVD (digital versatile disc) - a popular type of removable media that is the same
dimensions as a CD but stores up to 12 times as much information. It is the most
common way of transferring digital video, and is popular for data storage.
o DVD-ROM Drive - a device used for reading data from a DVD.
o DVD Writer - a device used for both reading and writing data to and from
a DVD.
o DVD-RAM Drive - a device used for rapid writing and reading of data
from a special type of DVD.
Blu-ray Disc - a high-density optical disc format for data and high-definition
video. Can store 70 times as much information as a CD.
o BD-ROM Drive - a device used for reading data from a Blu-ray disc.
o BD Writer - a device used for both reading and writing data to and from a
Blu-ray disc.
o
HD DVD - a discontinued competitor to the Blu-ray format...
Floppy disk - an outdated storage device consisting of a thin disk of a flexible
magnetic storage medium. Used today mainly for loading RAID drivers.
6
Iomega Zip drive - an outdated medium-capacity removable disk storage system,
first introduced by Iomega in 1994.
USB flash drive - a flash memory data storage device integrated with a USB
interface, typically small, lightweight, removable, and rewritable. Capacities vary,
from hundreds of megabytes (in the same ballpark as CDs) to tens of gigabytes
(surpassing, at great expense, Blu-ray discs).
Tape drive - a device that reads and writes data on a magnetic tape, used for long
term storage and backups.
Secondary storage
Hardware that keeps data inside the computer for later use and remains persistent even
when the computer has no power.
Hard disk - for medium-term storage of data.
Solid-state drive - a device similar to hard disk, but containing no moving parts
and stores data in a digital format.
RAID array controller - a device to manage several internal or external hard disks
and optionally some peripherals in order to achieve performance or reliability
improvement in what is called a RAID array.
Sound card
Enables the computer to output sound to audio devices, as well as accept input from a
microphone. Most modern computers have sound cards built-in to the motherboard,
though it is common for a user to install a separate sound card as an upgrade. Most sound
cards, either built-in or added, have surround sound capabilities.
Other peripherals
In addition, hardware devices can include external components of a computer system.
The following are either standard or very common.
Wheel Mouse
Includes various input and output devices, usually external to the computer system.
7
Input
Text input devices
o Keyboard - a device to input text and characters by depressing buttons
(referred to as keys), similar to a typewriter. The most common Englishlanguage
key layout is the QWERTY layout.
Pointing devices
o Mouse - a pointing device that detects two dimensional motion relative to
its supporting surface.
o Optical Mouse - a newer technology that uses Light to track the surface
under the mouse to determine the motion to be translated into cursor
movements on the screen.
o Trackball - a pointing device consisting of an exposed protruding ball
housed in a socket that detects rotation about two axes.
Gaming devices
o Joystick - a general control device that consists of a handheld stick that
pivots around one end, to detect angles in two or three dimensions.
o Gamepad - a general handheld game controller that relies on the digits
(especially thumbs) to provide input.
o Game controller - a specific type of controller specialized for certain
gaming purposes.
Image, Video input devices
o Image scanner - a device that provides input by analyzing images, printed
text, handwriting, or an object.
o Webcam - a low resolution video camera used to provide visual input that
can be easily transferred over the internet.
Audio input devices
o Microphone - an acoustic sensor that provides input by converting sound
into electrical signal
Generations of Computers
First Generations (1940-1956) Vacuum Tube
Second Generations (1956-1963) Transistors
Thirds Generations (1964-1971) I.C.
Fourth Generations (1971- Present)
Fifth Generations (Present and Beyond)
The Five Generations of Computers
8
The history of computer development is often referred to in reference to the
different generations of computing devices. Each generation of computer is characterized
by a major technological development that fundamentally changed the way computers
operate, resulting in increasingly smaller, cheaper, and more powerful and more efficient
and reliable devices.
First Generation - 1940-1956: Vacuum Tubes
The first computers used vacuum tubes for circuitry and magnetic drums for memory,
and were often enormous, taking up entire rooms. They were very expensive to operate
and in addition to using a great deal of electricity, generated a lot of heat, which was
often the cause of malfunctions. First generation computers relied on machine language,
the lowest-level programming language understood by computers, to perform operations,
and they could only solve one problem at a time. Input was based on punched cards and
paper tape, and output was displayed on printouts. The UNIVAC and ENIAC computers
are examples of first-generation computing devices. The UNIVAC was the first
commercial computer delivered to a business client, the U.S. Census Bureau in 1951
Vacum Tube
Second Generation - 1956-1963: Transistors
Transistors replaced vacuum tubes and ushered in the second generation of computers.
The transistor was invented in 1947 but did not see widespread use in computers until the
late 50s. The transistor was far superior to the vacuum tube, allowing computers to
become smaller, faster, cheaper, more energy-efficient and more reliable than their firstgeneration
predecessors. Though the transistor still generated a great deal of heat that
subjected the computer to damage, it was a vast improvement over the vacuum tube.
Second-generation computers still relied on punched cards for input and printouts for
output. Second-generation computers moved from cryptic binary machine language to
9
symbolic, or assembly, languages, which allowed programmers to specify instructions in
words. High-level programming languages were also being developed at this time, such
as early versions of COBOL and FORTRAN. These were also the first computers that
stored their instructions in their memory, which moved from a magnetic drum to
magnetic core technology. The first computers of this generation were developed for the
atomic energy industry
Third Generation - 1964-1971: Integrated Circuits
The development of the integrated circuit was the hallmark of the third generation of
computers. Transistors were miniaturized and placed on silicon chips, called
semiconductors, which drastically increased the speed and efficiency of computers.
Instead of punched cards and printouts, users interacted with third generation computers
through keyboards and monitors and interfaced with an operating system,
which allowed the device to run many different applications at one time with a central
program that monitored the memory. Computers for the first time became accessible to a
mass audience because they were smaller and cheaper than their predecessors.
Fourth Generation - 1971-Present: Microprocessors
The microprocessor brought the fourth generation of computers, as thousands of
integrated circuits were built onto a single silicon chip. What in the first generation filled
an entire room could now fit in the palm of the hand. The Intel 4004 chip, developed in
1971, located all the components of the computer - from the central processing unit and
memory to input/output controls - on a single chip. In 1981 IBM introduced its first
10
computer for the home user, and in 1984 Apple introduced the Macintosh.
Microprocessors also moved out of the realm of desktop computers and into many areas
of life as more and more everyday products began to use microprocessors. As these small
computers became more powerful, they could be linked together to form networks, which
eventually led to the development of the Internet. Fourth generation computers also saw
the development of GUIs, the mouse and handheld devices.
Fifth Generation - Present and Beyond: Artificial Intelligence
Fifth generation computing devices, based on artificial intelligence, are still in
development, though there are some applications, such as voice recognition, that are
being used today. The use of parallel processing and superconductors is helping to make
artificial intelligence a reality. Quantum computation and molecular and nanotechnology
will radically change the face of computers in years to come. The goal of fifth-generation
computing is to develop devices that respond to natural language input and are capable of
learning and self-organization
Some generation of Computer
Year Events
1971
The 4004-the first 4-bit microprocessor-is introduced by Intel. It boasts 2000
transistors with a clock speed of up to 1 MHz (megahertz).
1972 The first 8-bit microprocessor-the 8008-is released.
11
1974
The 8080 microprocessor is developed. This improved version of the 8008 becomes
the standard from which future processors will be designed.
1975
Digital Research introduces CP/M-an operating system for the 8080. The
combination of software and hardware becomes the basis for the standard
computer.
1976
Zilog introduces the Z80-a low-cost microprocessor (equivalent to the 8080).
The Apple I come into existence, although it is not yet in wide use.
1977
The Apple II and the Commodore PET computers, both of which use a 6502
processor, are introduced. These two products become the basis for the home
computer. Apple's popularity begins to grow.
1978
Intel introduces a 16-bit processor, the 8086, and a companion math coprocessor,
the 8087.
Intel also introduces the 8088. It is similar to the 8086, but it transmits 8 bits at a
time.
1980
Motorola introduces the 68000-a 16-bit processor important to the development of
Apple and Atari computers. Motorola's 68000 becomes the processor of choice for
Apple.
1981
The IBM personal computer (PC) is born; it contains a 4.7-MHz 8088 processor, 64
KB (kilobytes) of RAM (random access memory) and is equipped with a version of
MS-DOS 1.0 (three files and some utilities). Available mass-storage devices
include a 5.25-inch floppy drive and a cassette tape drive.
1982
Intel completes development of the 80286-a 16-bit processor with 150,000
transistors.
MS-DOS 1.1 now supports double-sided floppy disks that hold 360 KB of data.
1983
IBM introduces the XT computer with a 10-MB hard-disk drive.
MS-DOS 2.0 arrives-it features a tree-like structure and native support for harddisk
drive operations.
1984
The first computer with an 80286 chip-the IBM AT-enters the market. It is a 6-
MHz machine with a 20-MB hard-disk drive and a high-density, 1.2-MB 5.25-inch
floppy-disk drive.
1985 MS-DOS 3.2, which supports networks, is released.
1986
The first Intel 80386-based computer is introduced by Compaq; it features a 32-bit
processor with expanded multitasking capability (even though no PC operating
12
system yet fully supports the feature).
1987
MS-DOS 3.3 arrives, allowing use of 1.44-MB 3.5-inch floppy-disk drives and
hard-disk drives larger than 32 MB.
1988
IBM introduces the PS/2 computer series. A complete departure from previous
machines, its proprietary design does not support the hardware and software
available on IBM PCs or clones.
Microsoft (with the help of IBM) develops OS/2 (Operating System 2), which
allows 32-bit operations, genuine multitasking, and full MS-DOS compatibility.
Microsoft releases MS-DOS 4.0.
1989
Intel introduces the 80486 processor; it contains an on-board math coprocessor and
an internal cache controller (offering 2.5 times the performance of a 386 processor
with a supporting coprocessor).
1991 MS-DOS 5.0 offers a significantly improved DOS shell.
1992
The Intel i586 processor, the first Pentium, is introduced, offering 2.5 times the
performance of a 486.
IBM expands OS/2, and Microsoft Windows is introduced.
1993
MS-DOS 6.0 arrives. The term "multimedia" (the inclusion of CD-ROM drives,
sound cards, speakers, and so forth, as standard equipment on new personal
computers) comes into use.
1994
Intel delivers the first 100-MHz processor. COMPAQ Computer Corporation
becomes the largest producer of computers.
1995
Windows 95, code-named Chicago, is introduced by Microsoft. It features 32-bit
architecture.
IBM has now shipped over one million OS/2 Warp software packages.
The Internet, having expanded far beyond its beginnings as a network serving
government and university institutions, is now in everyday use by the rapidly
growing population with access to a modem.
Computer prices drop as performance increases. IBM purchases Lotus (maker of
the popular Lotus1-2-3 spreadsheet).
1995-
1996
Software manufacturers scramble to make their products compatible with Windows
95.
1997
Microprocessor speeds exceed the 200-MHz mark. Hard-disk drive and memory
prices fall while basic system configuration sizes continue to increase.
13
CD-ROM drives and Internet connections have become standard equipment for
computers.
1998
Personal computer performance continues to soar, and PC prices continue to fall.
CPU speeds exceed 450 MHz, and motherboard bus speeds reach 100 MHz.
Multimedia and Internet connections have become the de facto standard for new
PCs.
Entry-level machines are priced near the $500 mark.
Universal Serial Bus (USB) is introduced.
Windows 98 becomes the standard operating system for most new personal
computers.
1999
Processors exceed 600 MHz.
Microsoft readies Windows 2000 for release in February 2000, as Internet shopping
doubles over the holiday season.
Chapter – 2
Computer Hardware
14
Computer Hardware: - Computer Hardware is the physically part of computer,
including its digital circuitry as distinguished from the computer software that execution
within the Hardware
Computer Hardware:-The mechanical, magnetic, electronic, and electrical components
making up a computer system
Computer Hardware:-Devices capable of accepting and storing computer data,
executing a systematic sequence of operations on computer data, or producing control...
.
PC?
A personal computer (PC) is a computing device made up of many distinct electronic
components that all function together in order to accomplish some useful task (such as
adding up the numbers in a spreadsheet or helping you write a letter). Each component has
a very specific function
Part of a P.C.
The Case
The Power Supply
The Mother Board
The C.P.U.
Memory
Storage Devices
Onboard Disk drive connectors
Display Devices
Ports and Cables
Case
A computer case is the enclosure that encases all the components of a computer. All the
computer components mount to the inside the case -Case is essentially the mounting
platform far all the electronic devices platform for all the electronic devices the make up
the computer.
15
Types of Case
Full Tower 20 – 25 inch 5 or more Draw base
Mid Tower 16 – 19 inch 3 or 4 draw base
Mini Tower 12-15 inch 2 or 3 Draw base
Midi (Musical Instrument Digital interface) between mid and Mini
Desktop 5 to 7 inch 3 Draw Base
Slim line Very Small
Proprietary Case Depend on Company
Power Supply
SMPS (Switch Mode Power Supply) SMPS is the device in the computer that provides
the power supply in the computer because the computer components would not be able to
operate without power supply. It Converts AC into DC.
16
Types of Power Supply
AT (Advance Technology)
Power Connector 12 Pin (6+6)
Floppy Power Connector 4 Pin (Berg)
HDD/CDD Power Connector 4 Pin (Molex)
ATX (Advanced Technology Extended)
Power Connector 20 Pin
FDD Connector 4 Pin (Berg)
HDD/CDD 4 Pin (Molex)
Extra CPU Power 4 Pin
17
MATX (Macro Advanced Technology Extended)
Power Connector 20+4 = 24 Pin
FDD Connector 4 Pin (Berg)
HDD/CDD/DVD 4 Pin (Molex)
HDD/DVD 15 Pin (SATA)
Extra CPU Power 4 Pin
FDD Power Connector(Berg)
18
HDD/CDD/DVD power Connector (Molex)
SATA Power Connector
Mother Board
19
It is the most important components in the computer because it connects all the other
components of a PC together. The spine of the computer is the motherboard, otherwise
known as the system board
A motherboard is the central printed circuit board (PCB) in some complex electronic
systems, such as modern personal computers. The motherboard is sometimes
alternatively known as the main board, system board, or, on Apple computers, the logic
board. It is also sometimes casually shortened to mobo
Second Name
System board
Planner board
Logic board
Mother board
Mobo
20
Modern motherboards include, at a minimum:
Sockets (or slots) in which one or more microprocessors are installed
Slots into which the system's main memory is installed (typically in the form of DIMM
modules containing DRAM chips)
A chipset which forms an interface between the CPU's front-side bus, main memory, and
peripheral buses
Non-volatile memory chips (usually Flash ROM in modern motherboards) containing the
system's firmware or BIOS
Slots for expansion cards (these interface to the system via the buses supported by the
chipset)
Power connectors’ flickers, which receive electrical power from the computer power
supply and distribute it to the CPU, chipset, main memory, and expansion cards
Types of Mother Board
Accounting to integrate
Non–Integrated: - Each major assembly is installed in the computer as an expression
card. Non integrated boards can be easily identified because each expression slot is
usually occupied by one of the components. It is difficult to find nonintegrated
motherboards these days. Many of what would normally be called nonintegrated system
boards now incorporate the most commonly used circuitry (such as IDE and floppy
controllers, serial controllers, and sound cards) onto the motherboard itself. In the early
1990s, these components had to be installed externally to the motherboard.
21
Integrated Motherboard: -
Most of the components that would otherwise be installed as expansion are integrated
into the motherboard circuitry. Integrated system boards were designed for simplicity. Of
course, there’s a drawback to this simplicity: When one component breaks, you can’t just
replace the component that’s broken; the whole motherboard must be replaced. Although
these boards are cheaper to produce, they are more expensive to repair. With integrated
system boards, there is a way around having to replace the whole motherboard when a
single component breaks. On some motherboards, you can disable the malfunctioning
onboard component (for example, the sound circuitry) and simply add an expansion card
to replace its functions.
Accounting to Power Supply
XT (Extended Technology) Motherboard
CPU used with this mother board like: - 8085 8086 8087 8088
Ram used 1MB
IRQ 8(Interrupt Request Query)
DMA 4(Direct Memory Access)
Power Connector 9 Pin and 6+6 = 12 Pin
Not used in these days
All supporting components in the form of IC
22
AT (Advanced Technology) Motherboard
CPU used with this motherboard like 80286, 80386, 80486, P1 and P2
16 bit ISA slots (Industry Standard Architecture)
RAM used: - 8, 16, 32 MB
Special Slot for RAM
S1mm:- Single inline Memory Module
IRQ: - 16
DMA: - 8
Power Connector: - 6+6 = 12 Pin
23
ATX (Advanced Technology Extended) Motherboard
CPU used with this board like: - P2, P3 and P4
32 bit PCI slots (Peripheral Components Interconnects)
IRQ: - 16
DMA: - 8
Used in these days
Special slots for RAM
DIMM: - Dual Inline Memory Module
Power Connector 20 Pin
MATX (Macro Advanced Technology Extended)
CPU used with this board: - P4
32 bit 64 bit PCI slots
Used in these days
DIMM slots for RAM
Power Connector:-24 Pin (20 + 4)
24
NLX (New Low-profile Extended)
New Low-profile Extended is used in some low-profile case types. NLX continues the
trend of the technology it succeeded, Low Profile Extended (LPX), placing the expansion
slots (ISA, PCI, and so on) sideways on a special riser card to use the reduced vertical
space optimally. Fairly new motherboard Expansions slots are placed on the board as a
riser card. Not so durable.
25
Balanced Technology Extended (BTX)
In 2003, Intel announced its design for a new motherboard, slated to hit the market mid- to
Late-2004.When that time came; the new BTX motherboard was met with mixed
Emotions.
According to Position
Desktop Types: - These types of motherboard are placed on the cabinet horizontal like: -
P1 and P2
26
Tower Types: - These types of motherboard are placed on the cabinet vertically
like P3, P4
Most Visible Parts of Motherboard
Chipsets (Bridges)
CPU Socket
RAM Slots
Power Connectors
HDD/CDD and FDD Connector
Expansion Slots and Sockets
CMOS (Complementary Metal Oxide Semi Conductor)
BIOS (Basic Input Output System)
Back Panel
27
CPU Socket
Keyboard Connector
DIN (Dutch Industry Nome)
PS/2 Port (Keyboard and Mouse)
28
USB Port
Rj-45
Rj-11
Parallel Port
Serial Port
Parallel Port
29
SATA Port
IDE Connector
Serial and Parallel Port
30
Mouse Ports
Back panel of Computer
31
LPT (Line Printing Terminal)
Graphic Card
32
LAN Card
TV Tuner Card
33
Sound Card
Modem
34
IDE Connector
35
Chipsets
A chipset is a collection of chips or circuits that perform interface and peripheral functions
for the processor. This collection of chips is usually the circuitry that provides interfaces
for memory, expansion cards, and onboard peripherals and generally dictates how a
motherboard will talk to the installed peripherals.
Northbridge (B)
The Northbridge subset of a motherboard’s chipset is the set of circuitry or chips that
performs one very important function: management of high-speed peripheral
communications. The Northbridge subset is responsible primarily for communications
with integrated video using AGP and PCIe, for instance, and processor-to-memory
communications.
Southbridge(C)
The Southbridge chipset, as mentioned earlier, is responsible for providing support to the
myriad onboard peripherals (PS/2, Parallel, IDE, and so on), managing their
communications with the rest of the computer and the resources given to them.
36
Mother Board Connector
BIOS (Basic input output system) Aside from the processor, the most important chip on
the motherboard are the Basic Input/ Output System (BIOS) chip. This special memory
chip contains the BIOS software that tells the processor how to interact with the rest of
the hardware in the computer. The BIOS chip is easily identified: If you have a non-clone
computer (Compaq, IBM, HP, and so on), this chip has on it the name of the
manufacturer and usually the word BIOS. For example, the BIOS chip for a Compaq has
something like Compaq BIOS printed on it. For clones, the chip usually has a sticker or
printing on it from one of the major BIOS manufacturers (AMI, Phoenix/Award, Win
bond, and so on).
37
BIOS
CMOS
(Complementary Metal Oxide Semi-Conductor) save Date Time Hardware
Configuration and memory, CMOS is a Special kind of memory that holds the BIOS
configuration setting
Your PC has to keep certain settings when it’s turned off and its power cord is
unplugged.
These settings include the following:
Date
Time
Hard drive configuration Memory
To keep its settings, the memory must have power constantly. When you shut off a
computer, anything that is left in main memory is lost forever. To prevent CMOS from
losing its information (and it’s rather important that it doesn’t), motherboard
manufacturers include a small battery called the CMOS Battery to power the CMOS
memory. The batteries come in different shapes and sizes, but they all perform the same
function. Most CMOS batteries look like either large watch batteries or small, cylindrical
batteries.
38
Chapter – 3
Expansion Slots
An Extension of the main computer bus that include expansion slots for use by
compatible adapter such as memory board video adapter card hard disk controller and
SCSI interface card .The slots are used to install various devices in the computer to
expend its capabilities like: - VGA, NIC, Sound, USB, and TV Tuner Card
Some Slots on Motherboard:-EISA, MCA, ISA, PCI, AMR, CNR, AGP
The Extended Industry Standard Architecture (in practice almost always shortened to
EISA and frequently pronounced "eee-suh") is a bus standard for IBM compatible
computers. It was announced in late 1988 by PC clone vendors (the "Gang of Nine") as a
counter to IBM's use of its proprietary Micro Channel Architecture (MCA) in its PS/2
series
Year created: 1988
Width in bits: 32
Number of devices: 1 per slot
Capacity 8.33 MHz
Style: Parallel
Micro Channel Architecture
Micro Channel Architecture (in practice almost always shortened to MCA) was a
proprietary 16- or 32-bit parallel computer bus created by IBM in the 1980s for use on
their new PS/2 computers.
39
ISA Expansion Slots
If you have a computer made before 1997, chances are the motherboard has a few
Industry Standard Architecture (ISA) expansion slots. They’re easily recognizable
because they are usually black and have two parts: one shorter and one longer. Computers
made after 1997 generally include a few ISA slots for backward compatibility with old
expansion cards
CPU Supported 8088, 80286 and Pentium 1
Width in Bits 8 or16 bit
Color Black
Pin 62
Cut without Cut/One Cut
Capacity 4, 6, 8 MHz
Style Parallel
ISA Slots
40
PCI Expansion Slots
Most computers made today contain primarily Peripheral Component Interconnect
(PCI) Slots. They are easily recognizable because they are short (around 3 inches long)
and usually white. PCI slots can usually be found in any computer that has a Pentiumclass
processor or higher
Color:-White, Yellow, Green
Year created July 1993
CPU Supported Up to Pentium 2
Width in Bits 32 or 64
Color White
Capacity 133 MB/s (32bit)
Pin 62
Cut One Cut
Style Parallel
PCI Slots
41
PCIe Expansion Slots
The newest expansion slot architecture that is being used by motherboards is PCI Express
(PCIe). It was designed to be a replacement for AGP and PCI. It has the capability of
being faster than AGP while maintaining the flexibility of PCI. And motherboards with
PCIe will have regular PCI slots for backward compatibility with PCI.
PCI Express Slot
AGP Expansion Slots
Accelerated Graphics Port (AGP) slots are very popular for video card use. In the past,
if you wanted to use a high-speed, accelerated 3D graphics video card, you had to install
the card into an existing PCI or ISA slot. AGP slots were designed to be a direct
connection between the video circuitry and the PC’s memory. They are also easily
recognizable because they are usually brown, are located right next to the PCI slots on the
motherboard, and are shorter than the PCI slots.
Year created 1997
Width in bits 32
Capacity up to 2133 MB/s
Style Parallel
Cut One Cut
Color Brown
Version AGP 1x, AGP 2x, AGP 4x, AGP 8x
42
AMR Expansion Slots (Audio Modem Riser)
The manufacturers developed a way of separating the analog circuitry, for example,
modem and analog audio, onto its own card. This allowed the analog circuitry to be
separately certified. This slot and riser card technology was known as the Audio Modem
Riser
Color Brown
Cut One Cut
Pin 46
Used up to P3
43
CNR Expansion Slots
The Communications and Networking Riser (CNR) slots that can be found on some
Intel motherboards are a replacement for Intel’s AMR slots. Essentially, these 60-pin slots
allow a motherboard manufacturer to implement a motherboard chipset with certain
integrated features
Color Yellow, Brown
Bits 64 bit
Cut One Cut
Pin 60
Only for mATX
44
RAM Slots
DIPP (Dual Inline Pin Package)
Used with 8085, 8086, 8087, 8088 CPU
Look like IC
Storage capacity small
Took hours populating boards
Time-consuming and labor-intensive
Chip creep -they crept out of their sockets over time as the system went through thermal
cycles
SIPP (Single Inline Pin Package)
Used with 80286, 80386 CPU
Placed on motherboard vertically
Also small capacity
Little tiny wires for individual sockets
The wires would bend
Their omitted
45
SIMM (Single Inline Memory Module)
White Slots
RAM used in these slots
One cut and without cut slots
30 Pin and 72 Pin Packages
DIMM (Dual Inline Memory Module)
Used with p3 and P4 CPU
168(SDRam) and 184(DDR1) or 240(DDR2) pin
Color Black
Available in One Cut (DDRam) And Two Cut (SDRam)
Separate row of signal pins on each side
More than 200 signal pins
46
RIMM (Rambus Inline Memory Module)
Have different signal pins on each side
Mostly obsolete
Fairly new Slots for Ram
188 pin
Color Black
Two Cut
Used Only Server type Board
47
Chapter – 4
Memory
It is use to store information and instruction for CPU while program has been execute.
Memory is temporary storage because when the power is removed the information the
memory was holding disappear Computer memory refers to devices that are used to store
data or programs (sequences of instructions) on a temporary or permanent basis for use in
an electronic digital computer.
Two Types of Memory
Primary Secondary
ROM RAM
S. Ram D. Ram Storage Device
MROM L1 DIP HDD, CDD, FDD
PROM L2 SIP Pen Drive, FDD
EP ROM L3 FPM Tape Drive
EEP ROM EDO
SD RAM
DD RAM
RD RAM
ROM (BIOS): - ROM or Read Only Memory hold sets of instructions which tell the
MPU what to do, for instance a ROM will tell the CPU how to recognize key and which
key is to be pressed and how to light up the screen. Information stored on a ROM can be
read and can not be rubbed. It is permanently build in computer at the time of its
productions known as firmware.
Non-volatile memory
ROM and RAM are NOT opposites.
Main ROM BIOS is contained in a ROM chip on the motherboard.
There also found in adapter cards and removable storage.
Today, we use a type of ROM called EEPROM or Flash ROM.
48
In general, a PC can be fitted with up to five or more BIOS ROMs
System (Motherboard) BIOS
Video BIOS
Drive-controller BIOS
Network-adapter board BIOS
SCSI-adapter BIOS
Specialty software manufacturers, who make BIOS chips, supply the ROM chips.
The Primary suppliers are
Phoenix
AMI (American Mega trends)
Award
ROM (BIOS)
MROM: - (Masked ROM)
It stores instruction and data for MPU. It stored the bit of binary information,
programmed at the factory.
P ROM: - (Programmable ROM)
This is a type of ROM that can be programmed using special equipment; it can be written
to, but only once. This is useful for companies that make their own ROMs from software
they write, because when they change their code they can create new PROMs without
requiring expensive equipment, can be custom-programmed by the user (once) using
special circuitry.
49
EP ROM (Erasable Programmable ROM)
An EPROM is a ROM that can be erased and reprogrammed. A little glass window is
installed in the top of the ROM package, through which you can actually see the chip that
holds the memory. Ultraviolet light of a specific frequency can be shined through this
window for a specified period of time, which will erase the EPROM and allow it to be
reprogrammed again. Obviously this is much more useful than a regular PROM, but it
does require the erasing light.
.
50
EEP ROM (EA ROM) Electrically Alterable ROM
The next level of erase ability is the EEPROM, which can be erased under software
control. This is the most flexible type of ROM, and is now commonly used for holding
BIOS programs. When you hear reference to a "flash BIOS" or doing a BIOS upgrade by
"flashing", this refers to reprogramming the BIOS EEPROM with a special software
program. Here we are blurring the line a bit between what "read-only" really means, but
remember that this rewriting is done maybe once a year or so, compared to real readwrite
memory (RAM) where rewriting is done often many times per second! , can also be
programmed and erased by the user using ultraviolet light and special circuitry external to
the computer. , can be erased and reprogrammed by special circuitry within the computer.
RAM (Random Access Memory)
RAM is designed to act as short term memory and therefore also know as volatile
memory. A RAM holds information which is needed for a particular operating.
Types of RAM
DRAM (Dynamic)
Requires that data be refreshed (essentially rewritten) every millisecond
Industry-standard refresh time is 15ms
Refresh occurs when the memory controller accesses all the rows of data in the memory
chip.
DRAM uses only 1 transistor and 1 capacitor pair per bit
Available with one billion or more transistors
Tiny capacitors must retain their charge, or memory will be lost
The DRAM chip mostly is used for the main memory
Very dense (pack a lot of bits into a very small chip)
Inexpensive
Unfortunately it’s very slow
51
SRAM (Static RAM)
Consists of levels of Cache
L1 (internal cache):–Always built into the processor die.
L2 (external cache):-Originally installed on the motherboard but now on the processor
die running at full core speed.
L3 –Is present in high-end workstations and server processors (Pentium 4 Extreme
Edition).
Dynamic Random Access Memory
DIP (Dual Inline Package)
Took hours populating boards
Time-consuming and labor-intensive
Chip creep -they crept out of their sockets over time as the system went through thermal
cycles
DIPP Slot Ram
SIPP (Single Inline Pin Package)
Little tiny wires for individual sockets
The wires would bend
Their omitted
52
SIPP was a type of random access memory. Its name stands for Single Inline Pin Package
.It consisted of a small printed circuit board upon which were mounted a number of
memory chips. It had 30 pins along one edge which mated with matching holes in the
motherboard of the computer. This type of memory was used in 80286 and 386SX
systems. It was later replaced by SIMMs, which proved to be easier to install.30-pin SIPP
modules were pin compatible with 30-pin SIMM modules explaining why some SIPP
modules were in fact SIMM modules with pins soldered onto the connectors.
FPM (Fast Page Memory)
CPU used with 486/Pentium
30 Pin
8 bit
No Cut
SIMM Slots
53
EDO (Extended Data out RAM)
72 pin
32 bit
Introduced in 1995
SIMM Slot
One cut
Up to P1
SD RAM (Synchronous Data RAM)
Speed:-66 MHz, 100 MHz, 133 MHz
Introduce in 1996
2 Cut
DIMM Slots
Used up to PIII
Pin: - 168 Pin
54
DDR (Dual Data RAM)
Speed 100 MHz, 200 MHz, 300 MHz, 530 MHz
1 Cut
DIMM slots
Used with PIV
Pin 184 Pin (DDR2:- 240)
DDR-1 Ram
DDR2 SDRAM is a Double Data Rate Synchronous Dynamic Random Access
Memory interface. It supersedes the original DDR SDRAM specification and the two are
not compatible. In addition to double pumping the data bus as in DDR SDRAM,
(transferring data on the rising and falling edges of the bus clock signal), DDR2 employs
an I/O buffer between the memory and the data bus so that the data bus can be run at
twice the speed of the memory clock. The two factors combine to achieve a total of 4 data
transfers per memory clock cycle.
55
DDR3 SDRAM or Double-Data-Rate Three Synchronous Dynamic Random Access
Memory is a random access memory interface technology used for high bandwidth
storage of the working data of a computer or other digital electronic devices. DDR3 is
part of the SDRAM family of technologies and is one of the many DRAM (dynamic
random access memory) implementations.
RD RAM (RAM Bus Data RAM)
Direct Rambus DRAM or DRDRAM (sometimes just called Rambus DRAM or
RDRAM) is a type of synchronous dynamic RAM, designed by the Rambus Corporation.
Speed:-400 MHz , 533 MHz, 600 and 800 MHz
2 Cut
RIMM Slots
Pin 188
Used in Server type CPU
56
Chapter -5
Storage Device
Almost every computer made today uses some type of disk drive to store data and
programs until they are needed. Most drives need a connection to the motherboard so the
computer can “talk” to the disk drive. These connections are known as drive interfaces,
and there are two main types: floppy drive interfaces and hard disk interfaces. Floppy disk
interfaces allow floppy disk drives (FDD) to be connected to the motherboard and,
similarly, hard disk inter-faces do the same for hard disks. When you see them on the
motherboard, these interfaces are said to be onboard, as opposed to being on an expansion
card (off-board). The interfaces consist of circuitry and a port. Most motherboards
produced today include both the floppy disk and hard disk interfaces on the motherboard.
Today, the headers you will find on most motherboards are for Enhanced IDE
(EIDE/PATA) or Serial ATA (SATA). Advanced Technology Attachment (ATA) is the
standard term for what is more commonly referred to as Integrated Drive Electronics
(IDE). The AT component of the name was borrowed from the IBM PC/AT, which was
the standard of the day. However, because ATA is not the only technology that integrates
the drive controller circuitry into the drive assembly (ESDI, for example, was another),
IDE is somewhat of a misnomer and not the best term when referring only to ATA drives.
Storage media hold the Data being accessed as well as the file system need to operate and
data that to be saved
HDD: - (Hard Disk Drive) Hard disk system are used for permanent storage and quick
access .hard disk typically reside the computer and can hold the information than other
form of storage
Three types of HDD
ATA (Advanced Technology Attachment)
Power Cable:-4pin
Data Cable:-40 Pin
SATA (Serial Advanced technology Attachment)
Power cable:-15 pin
Data cable:-7 Pin
SCSI (Small Computer System Interface)
Power cable:-4 pin
Data cable:-50/68 Pin
FDD:- (Floppy Disk Drive) A floppy disk is a magnetic storage medium that uses a
flexible diskette made of thin plastic encased in a protective casing .The Floppy Disk
itself enable the information to be transported from one computer to another very easily
Two types of Floppy
5 ¼ 40 tracks 360 KB /1.2 MB
3 ¼ 80 Tracks 720/1.44 MB
57
Hard Disk
Date invented December 14, 1954
Invented by An IBM team led by Rey Johnson
Connects to Host adapter of system, in PCs typically integrated into
motherboard. Via one of:
PATA (IDE) interface
SATA interface
SAS interface
SCSI interface (popular on servers)
FC interface (almost exclusively found on servers)
USB interface
Market Segments Desktop computers
Mobile computing
Enterprise computing
Consumer electronic
A hard disk drive (often shortened as hard disk, hard drive, or HDD) is a non-volatile
storage device that stores digitally encoded data on rapidly rotating platters with magnetic
surfaces. Strictly speaking, "drive" refers to the motorized mechanical aspect that is
distinct from its medium, such as a tape drive and its tape, or a floppy disk drive and its
floppy disk. Early HDDs had removable media; however, an HDD today is typically a
sealed unit (except for a filtered vent hole to equalize air pressure) with fixed media
HDDs (introduced in 1956 as data storage for an IBM accounting computer) were
originally developed for use with general purpose computers. During the 1990s, the need
for large-scale, reliable storage, independent of a particular device, led to the introduction
of embedded systems such as RAIDs, network attached storage (NAS) systems, and
storage area network (SAN) systems that provide efficient and reliable access to large
volumes of data. In the 21st century, HDD usage expanded into consumer applications
such as camcorders, cellophanes (e.g. the Nokia N91), digital audio players, digital video
players, digital video recorders, personal digital assistants and video game consoles.
58
Technology
HDD record data by magnetizing ferromagnetic material directionally, to represent either
a 0 or a 1 binary digit. They read the data back by detecting the magnetization of the
material. A typical HDD design consists of a spindle that holds one or more flat circular
disks called platters, onto which the data is recorded. The platters are made from a nonmagnetic
material, usually aluminum alloy or glass, and are coated with a thin layer of
magnetic material, typically 10-20 nm in thickness with an outer layer of carbon for
protection. Older disks used iron (III) oxide as the magnetic material, but current disks
use a cobalt-based alloy
The platters are spun at very high speeds. Information is written to a platter as it rotates
past devices called read-and-write heads that operate very close (tens of nanometers in
new drives) over the magnetic surface. The read-and-write head is used to detect and
modify the magnetization of the material immediately under it. There is one head for
each magnetic platter surface on the spindle, mounted on a common arm. An actuator
arm (or access arm) moves the heads on an arc (roughly radially) across the platters as
they spin, allowing each head to access almost the entire surface of the platter as it spins.
The arm is moved using a voice coil actuator or in some older designs a stepper motor.
The magnetic surface of each platter is conceptually divided into many small submicrometer-
sized magnetic regions, each of which is used to encode a single binary unit
of information. Initially the regions were oriented horizontally, but beginning about 2005,
the orientation was changed to perpendicular. Due to the polycrystalline nature of the
magnetic material each of these magnetic regions is composed of a few hundred magnetic
grains. Magnetic grains are typically 10 nm in size and each form a single magnetic
domain. Each magnetic region in total forms a magnetic dipole which generates a highly
localized magnetic field nearby.
59
A write head magnetizes a region by generating a strong local magnetic field. Early
HDDs used an electromagnet both to magnetize the region and to then read its magnetic
field by using electromagnetic induction.
Later versions of inductive heads included metal in Gap (MIG) heads and thin film heads.
As data density increased, read heads using magneto resistance (MR) came into use; the
electrical resistance of the head changed according to the strength of the magnetism from
the platter. Later development made use of spintronics; in these heads, the magneto
resistive effect was much greater than in earlier types, and was dubbed "giant" magneto
resistance (GMR). In today's heads, the read and write elements are separate, but in close
proximity, on the head portion of an actuator arm. The read element is typically magnetoresistive
while the write element is typically thin-film inductive
HD heads are kept from contacting the platter surface by the air that is extremely close to
the platter; that air moves at, or close to, the platter speed .The record and playback head
are mounted on a block called a slider, and the surface next to the platter is shaped to
keep it just barely out of contact. It's a type of air bearing.
In modern drives, the small size of the magnetic regions creates the danger that their
magnetic state might be lost because of thermal effects. To counter this, the platters are
coated with two parallel magnetic layers, separated by a 3-atom-thick layer of the nonmagnetic
element ruthenium, and the two layers are magnetized in opposite orientation,
thus reinforcing each other. Another technology used to overcome thermal effects to
allow greater recording densities is perpendicular recording, first shipped in 2005, as of
2007 the technology was used in many HDDs.
The grain boundaries turn out to be very important in HDD design. The reason is that, the
grains are very small and close to each other, so the coupling between adjacent grains is
very strong. When one grain is magnetized, the adjacent grains tend to be aligned parallel
to it or demagnetized. Then both the stability of the data and signal-to-noise ratio will be
sabotaged. A clear grain boundary can weaken the coupling of the grains and
subsequently increase the signal-to-noise ratio. In longitudinal recording, the singledomain
grains have uneasily anisotropy with easy axes lying in the film plane. The
consequence of this arrangement is that adjacent magnets repel each other. Therefore the
magneto static energy is so large that it is difficult to increase a real density.
Perpendicular recording media, on the other hand, has the easy axis of the grains oriented
perpendicular to the disk plane. Adjacent magnets attract to each other and magneto static
energy are much lower. So, much higher a real density can be achieved in perpendicular
recording. Another unique feature in perpendicular recording is that a soft magnetic
under layer are incorporated into the recording disk. This under layer is used to conduct
writing magnetic flux so that the writing is more efficient. This will be discussed in
writing process. Therefore, a higher anisotropy medium film, such as L10-FePt and rareearth
magnets, can be used.
60
ATA Hard Drive
SATA Hard Drive
61
SCSI Hard Drive
Floppy Disk
Date invented 1969(8-inch),
1976(5¼-inch),
1982 (3½-inch)
Invented by IBM team led by David L. Noble
Connects to Controller via: cable
A Floppy disk is a data storage medium that is composed of a disk of thin, flexible
("floppy") magnetic storage medium encased in a square or rectangular plastic shell.
Floppy disks are read and written by a floppy disk drive or FDD, the initials of which
should not be confused with "fixed disk drive," which is another term for a (non
removable) type of hard disk drive.
62
Invented by IBM, floppy disks in 8-inch (200 mm), 5¼-inch (133.35 mm), and 3½-inch
(90 mm) formats enjoyed many years as a popular and ubiquitous form of data storage
and exchange, from the mid-1970s to the late 1990s. While floppy disk drives still have
some limited uses, especially with legacy industrial computer equipment,[2] they have
now been largely superseded by USB flash drives, external hard drives, CDs, DVDs, and
memory cards (such as Secure Digital).
Before hard disks became affordable, floppy disks were often also used to store a
computer's operating system (OS), in addition to application software and data. Most
home computers had a primary OS (and often BASIC) stored permanently in on-board
ROM, with the option of loading a more advanced disk operating system from a floppy,
whether it be a proprietary system, CP/M, or later, DOS.
The 5¼-inch 1.2 MB floppy disk drive
The 3½-inch 2.88 MB floppy disk drive
63
CD-ROM
Media type Optical Disc
Capacity 184 MB (8 cm)
650-900 MB (12 cm)
Read mechanism 150 KB/s (1×)
10800 KB/s (72x)
Write mechanism 150 KB/s (1×)
8400 KB/s (56x)
Usage Data storage, video, audio, open internet
CD-ROM (pronounced an initialize of "compact disc read-only memory") is a prepressed
compact disc that contains data accessible to, but not writable by, a computer for
data storage and music playback, the 1985 “Yellow Book” standard developed by Sony
and Philips adapted the format to hold any form of binary data
CD-ROMs are popularly used to distribute computer software, including games and
multimedia applications, though any data can be stored (up to the capacity limit of a
disc). Some CDs hold both computer data and audio with the latter capable of being
played on a CD player, while data (such as software or digital video) is only usable on a
computer (such as ISO 9660 format PC CD-ROMs). These are called enhanced CDs.
Although many people use lowercase letters in this acronym, proper presentation is in all
capital letters with a hyphen between CD and ROM. It was also suggested by some,
especially soon after the technology was first released, that CD-ROM was an acronym for
"Compact Disc read-only-media", or that it was a more "correct" definition. This was not
the intention of the original team who developed the CD-ROM, and common acceptance
of the "memory" definition is now almost universal. This is probably in no small part due
to the widespread use of other "ROM" acronyms such as Flash-ROMs and EEPROMs
where "memory" is usually the correct term.
64
Data Transfer Speeds
Transfer Speed KB/s Mb/s
1x 150 1.2288
2x 300 2.4576
4x 600 4.9152
8x 1200 9.8304
10x 1500 12.2880
12x 1800 14.7456
20x 3000 24.5760
32x 4800 39.3216
36x 5400 44.2368
40x 6000 49.1520
48x 7200 58.9824
50x 7500 61.4400
52x 7800 63.8976
56x 8400 68.8128
72x 10800 88.4736
Blu-ray Disc
Media type High-density optical disc
Encoding MPEG-2, H.264/MPEG-4 AVC, and VC-1
Capacity 25 GB (single-layer)
50 GB(dual-layer)
1 TB to 5TB (future)
Block size 64kb ECC
Read mechanism 405nmlaser:
1×at36Mbit/s(4.5MByte/s)
2×at72Mbit/s(9MByte/s)
4×at144Mbit/s(18MByte/s)
6×at216Mbit/s[1](27MByte/s)
8×at288Mbit/s(36MByte/s)
12× at 432 Mb/s (54 MB/s)
65
Usage Data storage
High-definition video
High-definition audio
PlayStation 3
games
possibility of Quad HD 2160p
Blu-ray Disc (also known as Blu-ray or BD) is an optical disc storage medium designed
to supersede the standard DVD format. Its main uses are for storing high-definition
video, PlayStation 3 games, and other data, with up to 25 GB per single layered, and 50
GB per dual layered disc. The disc has the same physical dimensions as standard DVDs
and CDs. The name Blu-ray Disc derives from the blue-violet laser used to read the disc.
While a standard DVD uses a 650 nanometer red laser, Blu-ray uses a shorter
wavelength, a 405 nm blue-violet laser, and allows for almost six times more data storage
than a DVD. During the format war over high-definition optical discs, Blu-ray competed
with the HD DVD format. Toshiba, the main company supporting HD DVD, ceded in
February 2008, and the format war ended;[2] in July 2009, Toshiba announced plans to
put out its own Blu-ray Disc device by the end of 2009. Blu-ray Disc was developed by
the Blu-ray Disc Association, a group representing makers of consumer electronics,
computer hardware, and motion pictures
Data rate Write time for Blu-ray Disc (minutes)
Drive speed
Mb/s MB/s Single-Layer Dual-Layer
1× 36 4.5 90 180
2× 72 9 45 90
4× 144 18 23 45
6× 216 27 15 30
8× 288 36 12 23
66
12×* 432 54 8 15
SCSI
Small Computer System Interface or SCSI (pronounced scuzzy), is a set of standards
for physically connecting and transferring data between computers and peripheral
devices. The SCSI standards define commands, protocols, and electrical and optical
interfaces. SCSI is most commonly used for hard disks and tape drives, but it can connect
a wide range of other devices, including scanners and CD drives. The SCSI standard
defines command sets for specific peripheral device types; the presence of "unknown" as
one of these types means that in theory it can be used as an interface to almost any
device, but the standard is highly pragmatic and addressed toward commercial
requirements. SCSI is an intelligent, peripheral, buffered, peer to peer interface. It hides
the complexity of physical format. Every device attaches to the SCSI bus in a similar
manner. Up to 8 or 16 devices can be attached to a single bus.
There can be any number of hosts and peripheral devices but there should be at
least one host. SCSI uses hand shake signals between devices, SCSI-1, SCSI-2 have the
option of parity error checking. Starting with SCSI-U160 (part of SCSI-3) all commands
and data are error checked by a CRC32 checksum. The SCSI protocol defines
communication from host to host, host to a peripheral device, and peripheral device to a
peripheral device. However most peripheral devices are exclusively SCSI targets,
incapable of acting as SCSI initiators--unable to initiate SCSI transactions themselves.
Therefore peripheral-to-peripheral communications are uncommon, but possible in most
SCSI applications. The Symbiosis Logic 53C810 chip is an example of a PCI host
interface that can act as a SCSI target
SCSI interfaces
67
SCSI Hard Drive
Tape Drive
A tape drive, which is also known as a streamer, is a data storage device that reads and
writes data stored on a magnetic tape. It is typically used for archival storage of data
stored on hard drives. Tape media generally has a favorable unit cost and long archival
stability. Instead of allowing random-access to data as hard disk drives do, tape drives
only allow for sequential-access of data. A hard disk drive can move its read/write heads
to any random part of the disk platters in a very short amount of time, but a tape drive
must spend a considerable amount of time winding tape between reels to read any one
particular piece of data. As a result, tape drives have very slow average seek times.
Despite the slow seek time, tape drives can stream data to tape very quickly. For
example, modern LTO drives can reach continuous data transfer rates of up to 80 MB/s,
which is as fast as most 10,000 rpm hard disks.
68
DVD Recordable
DVD-R is a DVD recordable format. A DVD-R type has a storage capacity of 4.71 GB
(or 4.38 GB), although the capacity of the original standard developed by Pioneer was
3.95 GB (3.68 GB). Both values are significantly larger than the storage capacity of its
optical predecessor, the 700 MB CD-R – a DVD-R has 6.4 times the capacity of a CD-R.
Pioneer has also developed an 8.54 GB dual layer version, DVD-R DL, which appeared
on the market in 2005.Data on a DVD-R cannot be changed, whereas a DVD-RW (DVDrewritable)
can be rewritten multiple (1000+) times. DVD-R (W) is one of three
competing industry standard DVD recordable formats; the others are DVD+R(W) and
DVD-RAM.
ATA DVD Writer
SATA Connector on DVD Writer/Rom
Chapter – 5
System Buses
69
It is communicating port between MPU and peripheral. It is nothing but groups of wire
which carry bits.
Three types of bus
Address Bus: - It is groups of 16 lines. The address bus is unidirectional that means data
flow in one directions that is MPU to peripheral .MPU uses the address but to identity the
peripheral and memory location.
Data Bus: - It is groups of 8 lines used for the flow of Data bi-directional that means data
flow from peripheral to MPU and MPU to peripheral. MPU used data bus to travel data.
Control Bus: - Control Bus is signal lines MPU uses this line to provide control signal to
peripheral.
CPU (Central Processing Unit)
A Central Processing Unit (CPU) or processor is an electronic circuit that can execute
computer programs, which are actually sets of instructions. This term has been in use in
the computer industry at least since the early 1960s. The form, design and
implementation of CPUs have changed dramatically since the earliest examples, but their
fundamental operation remains much the same.
The “Brain” of any computer is the central processing unit (CPU). This component does
all the calculations and performs 90 percent of all the functions of a computer
Receive and store data in to main storage memory
Control sequence of Operations
Give commands to all parts of the computer system.
Carry out processing and to output the result
Early CPUs were custom-designed as a part of a larger, sometimes one-of-a-kind, and
computer. However, this costly method of designing custom CPUs for a particular
application has largely given way to the development of mass-produced processors that
are made for one or many purposes. This standardization trend generally began in the era
of discrete transistor mainframes and minicomputers and has rapidly accelerated with the
popularization of the integrated circuit (IC).
The IC has allowed increasingly complex CPUs to be designed and manufactured to
tolerances on the order of nanometers.
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Both the miniaturization and standardization of CPUs have increased the presence of
these digital devices in modern life far beyond the limited application of dedicated
computing machines. Modern microprocessors appear in everything from automobiles to
cell phones and children's toys.
CPU Unit
Arithmetic and Logic Unit
Control Unit
Memory Storage Unit
ALU: - The ALU is a section where all the arithmetic and logic functions are carried out.
We know that every arithmetic operation requires two operations. The operation then
produces a result.
Control Unit: - The CPU directs all operations in side the computer it is known as nerve
center of the computer. It gives command to transfer data from the input device to the
memory of arithmetic and logic unit. It also transfers the result from ALU to the memory
and on to the output device for printing.
Memory Unit: - Immediate access storage (IAS) which is a part of Central Processing
Unit it self.
(AMS) Auxiliary Memory Storage or backing storage which is external to central
processing unit.
Memory stores instructions waiting to be obeyed by other components of the CPU.
Socket/Slot Processors
Socket 4:-Pentium 60/66, Pentium 60/66 Over Drive
Socket 5: -Pentium 75-133, Pentium 75+ Overdrives, and AMD K5
Socket 6:- 486DX4, 486 Pentium Over Drive
Socket 7:- Pentium 75-200, Pentium 75+ Over Drive, Pentium MMX, AMD
K6
Super Socket 7:-AMD K6-2, K6-III
Socket 8:-Pentium Pro
Slot 1:-Pentium II, Pentium III, Celeron, and all SECC and SECC2
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Slot 2:-Pentium II Xeon, Pentium III Xeon
Slot A: - Early AMD Athlon
Socket 370:- PPGA processors, including Pentium III and Celeron
Socket 423:-Early Pentium 4
Socket A :-( Socket 462) AMD Athlon, Athlon XP, Athlon XP-M, Athlon
MP, Thunderbird, Duron, Sempron
Socket 478:-Pentium 4, Pentium 4 Extreme Editions, and Celeron
Socket 479:-Pentium M, Celeron M
Socket 486:-80486
Socket 563:-AMD low-power mobile Athlon XP-M
Socket 603:-Intel Xeon
Socket 604:-Intel Xeon with Micro FCPGA package
Socket 754:-Athlon 64, Sempron, and Turion 64
Socket 771:-Xeon 50x0 Dual-cores
Socket T :-( LGA 775) Pentium 4, Pentium D dual-core, Celeron D, Pentium
Extreme Edition
Socket 939:-Athlon 64, Athlon 64 FX, and Athlon 64 X2, Opteron 100-series
Socket/Slot Processors
Socket 940:-Athlon 64 FX (FX-51), Opteron
Socket F :-( Socket 1207) Replaces Socket 940 when used with Opteron
multiprocessor Systems)
Socket AM2:- AMD single-processor systems, replaces Socket 754 and
Socket 939
Socket S1:-AMD-based mobile platforms, replaces Socket 754 in the mobile
sector
PAC418:-Itanium
PAC611:- Itanium 2
Some Range of C.P.U
8085
Launched by: - 1978
Data Bus: - 8 bit
Address Bus: - 20 bit
Ram: - 1mb
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Speed: - 4.7 MHz
8088
Launched by: - 1979
Data Bus: - 8 bit
Address Bus: - 20 bit
Ram: - 1Mb
Speed: - 8 MHz
80186
Launched by: - 1990
Data Bus: - 16 bit
Address Bus: - 20 bit
Ram: - 1Mb
Speed: - 8 MHz
80286
Launched by: - 1982
Data Bus: - 16 bit
Address Bus: - 24 bit
Ram: - 16 mob, 8 Mb
Speed: - 8, 10, 12.5 MHz
80386
Launched by: - 1985
Data Bus: - 32bit
Address Bus: - 32 bit
Ram: - 16 Mb
Speed: - 16 to 33 MHz
80486
Launched by: - 1989
Data Bus: - 32 bit
Address Bus: - 32 bit
Ram: - 16 to 32 Mb
Speed: - 33 MHz
80586
Launched by: - 1991
Data Bus: - 32 bit
Address Bus: - 32 bit
Ram: - 16 Mb
Speed: - 66 MHz
Pentium1
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Launched by: - 1993
Data Bus: - 64 bit
Address Bus: - 32 bit
Ram: - 32 Mb
Speed: - 60 to 200 MHz
Pentium Pro
Launched by: - 1995
Data Bus: - 64 bit
Address Bus: - 32 bit
Ram: - 32, 64 Mb
Speed: - 150 to 200 MHz
Socket: - 8
Voltage: - 2.5v
Cache memory: - 32kb
Pentium2
Launched by: - 1997
Data Bus: - 64 bit
Address Bus: - 32 bit
Ram: - 32, 64, 128 Mb
Speed: - 233 to 450 MHz
Socket: - (SECC) single Edge Contact Cartage
Voltage: - 3.3v
Cache memory: - 32kb
Slot: - I, II
Celeron (P3)
Launched by: - 1999
Data Bus: - 64 bit
Address Bus: - 32 bit
Ram: - 32, 64, 256 Mb
Speed: - 400 to 600 MHz
P III
Launched by: - 1999
Data Bus: - 64 bit
Address Bus: - 32 bit
Ram: - 64, 128, 256 Mb
Speed: - 450 to 1000 MHz
Slot: - SECC (single edge contact cartage)
Socket: - 370
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Voltage: - 3.3v
Cache memory: - 32kb
P IV
Launched by: - 2003
Data Bus: - 64bit
Address Bus: - 64bit
Ram: - 128, 256, 512, 2 GB, 2 GB
Speed: - 1.4 GHz to 3.06 GHz
Socket: - 427, 478, LGA 775
Voltage: - 1.3v to 1.7v
Cache memory: - Up to 512 kb
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Chapter - 6
Monitor
Monitor is an output device, which is used to obtain a soft copy of the image.
Basic terms of display
Pixel:- Pixel is the smallest dot, which can be, represent on the screen
Resolution:-It’s the total number of pixel present on the screen (width by height).
Resolution:-
Monitor type Height Width
Color graphics Adapter (CGA) 320 pixels 200 pixels
Enhanced graphics Adapter (EGA) 640 pixels 350 pixels
Video graphics Array (VGA) 640 pixels 480 pixels
Super VGA (SVGA) 800 pixel 600 pixels
1024 pixels 768 pixels
Triad:- Triad is the combination of the three primary color, which form the final color
(Red, Green, and Blue).
Horizontal Scanning: - It is process of drawing Horizontal line on the Screen.
Vertical Scanning:- It is the process of shifting to the line Vertical Scanning
Raster: - It is the continuous Horizontal and Vertical Scanning.
Retrace:- It is the beginning of the Image formation from the first Horizontal line after
the data is sent again
Convergence:- It’s the process, which through which the different color of the electron
beams combined, at the convergence point on the shadow mask to produced the final
color.
Inside CRT Displays
If we open a CRT display we can find following circuit:
Video Drive Circuit
Vertical Drive Circuit
Horizontal Drive Circuit
Power Supply Circuit
The video signal is amplified by a simple transistor switch (Video drive circuit) that
drives the CRT video-control grid. A contrast control affects the separation between light
and darkness by adjusting the amount of amplification given to the video signal.
The vertical drive circuit controls the up-down position of the electron beam. A vertical
sweep oscillator (54 to 72 Hz depending on the monitor type) provides a ramping signal
that resembles a saw tooth wave. The vertical ramp is triggered by the presence of a
vertical sync transistor circuit that connects directly to the vertical deflection coil (or
yoke) fixed to the neck of the CRT.
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Diagram of Monochrome CRT
The magnetic field produced by the vertical ramp signal maneuvers the electron beam. As
the ramp starts from 0 and increases in amplitude, the beam moves down the screen.
The horizontal drive circuit controls the left-right position of the electron beam. A
horizontal oscillator (15.85 to 38 kHz depending on the monitor type) provides a short
square-wave pulse
The horizontal pulse is triggered by the presence of a horizontal sync pulse .
This horizontal pulse signal is amplified by an output driver transistor circuit that
connects directly to the horizontal deflection yoke fixed to the neck of the CRT.
As with the vertical system, the magnetic field produced by the horizontal signal
maneuvers the electron beam.
That high voltage is produced by a device known as an FBT (fly back Transformer). The
FBT “spikes” a relatively low voltage up to a much higher level.
A high-voltage pulse is developed during the horizontal retrace (the brief time when the
beam has finished drawing one line and is turned off to be repositioned for the next line).
The primary winding in the fly back transformer is coupled to the horizontal output.
When the horizontal signal drops to 0, it does so almost instantly that drives transformer
output to a very high level.
Fly back voltages can be from 15,000 to 30,000 Vdc.
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Chapter - 7
Printers
Objective
Printers
Daisy wheel printer
Chain printer
Drum printers
Dot-matrix printers
Inkjet printers
Laser jet printers
Printers
Printers are output devices used with the computer. Printer is used to get a “Hard
Copy” of the results, to get permanent output on the paper or some other medium
such as the overhead projector (OHP) film etc.
Today, printers are capable of high-quality monochrome i.e. single color and
multi-color printout at a very high speed. Most of the printer can also produce
graphic i.e. images other than plain text on the paper.
Printers are often categorized based on the mechanism used by the printer to
print the image and also they can be categorized based on the image formation
method used by them.
Types of the printers based on the image formation method are:
Fully Formed Character printer and
Bit Image printer
Types of the printers based on the printing mechanism are:
Impact and
Non-impact printers
Image Formation Method
Different printers use different method to produce the required output on the
paper or any other output media such as the OHP transparencies etc.
The quality of the output and different capabilities of the printer such as being
able to print graphic image, depends on the method used to generate the image by
the printer.
Two possible image formation methods are FULLY FORMED CHARACTER
printer and BIT IMAGE printer.
Fully Formed Character Printers
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Typewriter is a very good example of the fully formed character type printing.
Just like the typewriter, in a fully formed character type of printer, all the
printable characters are mad in advance and provided in the printer, as a part of
printer hardware itself.
Almost all the fully formed character type printer use impact method to print on
the paper. In this method first a hammer strikes the required character shape, this
makes the character shape to press some kind if inked ribbon against the paper,
this will produce the required shape on the paper.
Most of the time the hammer is powered by a solenoid, which is controlled by the
electronics of the printer and the computer.
One positive thing about this printing technology is, it produces very good-quality
output Negative points are, one can not use these printers to print graphics image,
most of these printers generate high noise because of their impact mechanism
and these printers have a very limited character styles available.
Some common fully formed character type printers are
Daisy-Wheel printer
Chain printer
Drum printer
Bit-Image Printers
In this method printer does not contain any specific character shape, instead it
prints the required character shape using a matrix of dots.
These dots are arranged to resemble the character or shape that you want to print.
In most of these printers, characters are formed from dots placed within a
matrix this is the reason these printers would be “bit-image printers”.
The bit-image printers are most popular printers today and the reason is a bitimage
printer is a very versatile printer, it can be used to print text as well as
graphic images.
By controlling individuals’ dots, computer can make these printers to produce any
required pattern.
If one is using a Dot-Matrix printer, then just by sending instruction to the
printer one can change, the character style, the height of the character or even
the width of the character, anytime during the printing, without changing any
hardware.
The speed and the image quality produced by the bit-image printer depend very
much on the technology used to generate these images.
At the lower end is an ordinary Dot Matrix printer, which provides output that
looks like ordinary computer printed output, whereas at the higher end a Laser
printer can give output look like pages of this printed book.
Printing Mechanism
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One can also divide printers into two categories, Impact and Non-impact based on
their printing mechanism.
Printing mechanism refers to the method used by the printer to produce the image
on the output media, such as paper, OHP transparency etc.
Impact Printers
Impact printers; actually use impact to create an image on the output media.
All impact printers smash a hammer of some kind against an inked ribbon onto
the paper; this makes impact mark to appear on the paper.
Some common impact type printers are:
o Daisy-Wheel Printer
o Dot-Matrix Printer
o Chain Printer
o Drum Printer
A Dot-Matrix printer is an impact type printer, which works on bit-image
technology.
This printer creates image on the output media, by first forming the required
shape using a matrix of dots and then striking the media through inked ribbon.
These printers are very low-priced and economical to operate compared to the
printers using other technologies.
Advantage
Impact printer’s design and functions are relatively straightforward and easy to
understand compared to a non-impact printer.
As these printers generate image by striking the output media, most impact
printers can output media, most impact printers can output on any media, where
the ink can be used to print and media can be fed into the printer.
Another very major advantage of the impact printers is that they can used to print
on multipart forms.
As the Impact printers strike the media to create an impression, they can print not
just through a ribbon but also through several sheets of paper and carbon paper to
print multiple carbon copies in a single pass.
For a number of business applications where exact carbon copies are required,
impact printers are the only available option.
Disadvantage
The main advantage of the impact printer is also its main disadvantage, the
hammer striking against the ribbon and paper which allows multiple copies to be
made also generates noise.
Non-Impact Printer
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Non-Impact printers do not strike any ribbon or paper to produce the image,
instead they use ink spraying, electrostatic magnetization or heat process to
produce the required image on the image or any other output media.
The common non-impact technologies are :
Inkjet
Laser
Soundless operation and very high quality output of these printers are making
them very popular.
At the lower price end Inkjet printers are replacing Dot-Matrix printers and at the
higher end Laser printer is slowly becoming one of the most common printer.
One disadvantage with these printers is they cannot be used to print carbon copies
or multiples copies in a single pass, which requires some kind of impact to be
applied.
Daisy Wheel Printer
Daisy-Wheel (or Petal-Wheels) was one of the first impact type printers used with the
computer. They were initially used with dedicated word processors, because of their
very high quality output. These are fully formed character type of printers, all the
characters that these printers are capable of printing, are made available with the
printer on a wheel like structure. The name Daisy Wheel is given to these printers
because of the daisy flower like shape of the character wheel used on these printers.
These wheels are made of high-impact durable plastic or metal. Each spoke or the
petal of the Daisy Wheel contains one letter or symbol. When a character is to be
printed the wheel spins on its center to bring that character at the correct printing
position under the small hammer. Once the character reaches correct position, it is
struck by the hammer activated by a solenoid. This makes the character on the petal
to press through an inked ribbon and strike the paper, leaving an image of the
character on the paper. One can change these wheels to print different type of
characters, as these wheels are available in a wide range of letter styles and sizes.
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Chain Printer
Chain printer is another example of the fully formed character type printers. The name
chain printer is used for these printers because on these printers all the printable
characters are attached to a chain like structure. When ever a character is to be printed
The chain rotates in a circular fashion until the required character reaches correct
position. When the character to be printed reaches correct position a hammer strikes the
character to the inked position and Through the ribbon character’s image gets printed on
the paper. These printers provide very high-speed output and are mainly used in the high
volume works such as printing of electricity bill, telephone bills etc. On a normal size
computer stationary page of 132 characters per line, these printers print at the speed of
about 15 to 30 pages per minute (PPM).
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Drum Printers
Drum printers are another variation of the fully formed character type impact printers.
When a character is to be printed at a particular position The drum is rotated until the
desired character comes at the correct position. Next, a hammer strikes the paper
against the inked ribbon and the character on the drum, making the character’s image
to appear on the paper. Printer allows the entire line to be printed at a time, which give it
the name of “Line printer”. These printers provide very high-speed output and are mainly
used in high volume works such as printing of electricity bill, telephone bills, pay slips of
big corporations etc On a normal size computer stationary page of 132 characters per
line, these printers provide about 15 to 30 page per minute (PPM) output. These printers
achieve this high speed by printing all the letters of the line at one rotation of the drum, as
the drum rotates different letters of the line gets printed and in one rotation of the drum
all the letters of the line gets printed. For example of you want to print “DIFFERENT
LETTERS” First all the letters “A” in the line will get printed, next all the “B”, then all
the “C” and so on until all the letters of the line is printed, so, our example will be printed
in the following fashion The high-speed rotation and printing gives a distinctive uneven
look to the output produced by the drum printers.
D E E E E
D FFE E E E
DIFFE E E E
DIFFE E LE E
DIFFE EN LE E
DIFFEREN LE ER
DIFFEREN LE ERS
DIFFERENT LETTERS
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Dot-Matrix Printers
Dot-Matrix printers are bit image impact type of printers. These printers form characters
and images by placing pattern of dots on the paper by striking inked ribbon with a
number of small pins. These printers use a print head that shuttles back and forth across
the width of the paper and a number of thin print wires on the head act as hammers that
strike the ribbon and squeeze ink from ribbon to paper. Most Dot-Matrix printer models
are inexpensive, small, lightweight and very efficient at their job. As these are impact
type of printer’s one main drawback of these printers is the noise generated by them, but
compared to fully formed character type impact printers such as the Daisy-Wheel printer,
these printers are less noisy. Dot-Matrix printers have one real advantage over all the
other kinds of printers. Another advantage of these printers is they are very versatile, as
they generate character or image using combination of dots i.e. these printers can be used
to produce graphs, charts and ven pictures under the computer’s control. The per page
printing cost of Dot-Matrix printers are very-very low, because the only consumable
required for the printing is the printer ribbon which can be re-inked or refilled at a very
cheap price. Dot-Matrix printers print ant text character by character, so the speed of
these printers is expresses in Characters Per Second or more commonly CPS. Common
printing speed ranges from 50 CPS to 500 CPS, i.e. a normal page could be printed at the
speed of one quarter to 6 pages per minute (PPM). If we consider 1 CPS to be about 10-
12 Words Per Minute (WPM), in typing terms, this speed is in a range of about 600 to
6000 WPM. Many of the Dot-Matrix printers offer color-printing option, either using a
single multicolor ribbon or using complex multiple color ribbons.
To speed up the printing operation, most of the Dot-Matrix printers print bi-directionally,
i.e. they print one row from left to right and then the next row from right to left. This
mode of operation saves the time that would be wasted for print head to return to the left
side of the page to start the next line. The Dot-Matrix printers available in the market can
be broken down into three different segments based on their capability. The extremely
high-volume models useful for large heavy duty work such as electricity or telephone
bill printing, used by the big corporations, banks etc. The cost of these printers can be
very high .The high-volume models which are useful for people running small job works
or for small business whose output requirements are higher than normal. The personal
models useful for small business, office, home users, sell for Rs.7000 to 10,000.
The Dot-Matrix printer available in the market can also be classified according to the
number of pins used in their print head. The 9 pin print head is most common and lowcost
printers but their print quality is very poor. These printers have ninepins in a
single vertical column. The 24 pin print head is highest quality Dot-Matrix printers.
These printers provide very high quality print. The 24-pin heads usually have three offset
columns of eight pins each.
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Color Dot-Matrix Printers
Initially color Dot-Matrix printing required a separate printer, but now most of the Dot-
Matrix printer has option to add color kit and color ribbon to convert a normal single
color printer into color printer. The four-color ribbons of black, yellow, red and blue
bands allow the printer to produce up to seven different colors. These ribbons cost two to
three times more than the normal black ribbons. So, if you use color only occasionally,
it’s good idea to use a black ribbon for normal printing and swap it for four-color ribbon
only when you need the color. To prevent the ribbon from drying out, you can store them
in a plastic bag when not in use. Color Dot-Matrix printer can be used to print business
graphs and charts as well as to produce hard-copy of presentation materials such as charts
with clip-arts etc., it can also be used to create colorful OHPs. Another valuable use for
color Dot-Matrix printer is in the creation of drafts of output that will later be generated
by a color page printer. As the cost of color page printers have dropped, their initial cost
and printing cost are still significantly higher than a color Dot-Matrix printer. A color
Dot-Matrix printer should be capable of producing high quality color printout with deep,
saturated colors with little or no white showing through. Printing in multiple colors with a
Dot-Matrix printer could be very slow process, as most of the time the print head has to
make more than one pass to blend different colors.
.
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Inkjet Printers
Inkjet printers occupy a position between Dot-Matrix printers and the Laser printers.
These are small printers that provide the resolution of the Laser printers at accost i.e.
close to the Dot-Matrix printer. But, per page printing cost of the Inkjet printer is much
higher than the Dot-Matrix printers; it is even higher than that of laser printers. These
printers are perfect compromise of cost, speed and quality. Only with the close inspection
one can detect the difference between Laser printer output and the Inkjet output. Another
quality of the Inkjet is these printers print very silently; one does not hear the noise
associated with the Dot-Matrix printers. Inkjet uses bit image formation method.
Character shape is printed using matrix of dots. Instructions given to printer can change
the character style, height of character without any change in hardware. Inkjet is a nonimpact
printer i.e. produces image by ink spraying, Electrostatic magnetization or heat
process. Print operation is soundless. Inkjet cannot be used to print carbon copies or
multiple copies in a single pass. Inkjet sprays the ink from tiny nozzles of the printer
cartridge onto the paper to place pattern of dots on paper to generate image. Output
quality of Inkjet printer look similar to the Laser printer. Inkjet uses piezo-electric crystal
or a resistor to force the ink out of the nozzle of the ink cartridge. There are two types of
inkjet technologies
Piezo-Electric Technology
Bubble Technology
Piezo-Electric Technology
Piezo-electric crystals bend or expand when electric charge is applied to the crystal; this
forces the minute quantity of ink out of the nozzle on to the paper. A sharp digital pulse
of electricity cause piezo-electric crystal to switch & force ink through the nozzle onto
the paper
Bubble Technology
A resistor heats creating small air bubble, to force ink out through the nozzle.
A small electric current is passed through the bottom of chamber, which heats the ink for
a fraction of second at a temperature of 300°C. This temperature boils the ink and forms
a bubble, and bubble in turn pushes a tiny amount of ink through the nozzle on to the
paper. The bubble then cools off and collapses creating a suction that pulls fresh ink into
the chamber. The Jet of the inkjet printer can be of two types -Pulsing Jet, Continuous
stream Jet
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Color Inkjet
The color inkjet produce very good quality color images, there are two main reason for
this, first is the Inkjet printer sprays the ink directly onto the paper there is no ribbon in
between to dull the image being printed, and the second reason is the Inkjet’s ink remain
fluid enough even after they have been sprayed on the paper to blend together.
This gives color Inkjet printers the capability to mix their primary colors together to
create intermediary tones. A full-color Inkjet printer needs at least four print heads,
one for each primary color (yellow, magenta yan) and one for black. Some printers
provide all this three primary colors in a single print head also some printers do not
provide the black color print head at all and Produce black color by mixing the three
primary colors, but this will not give good, saturated, dark black color, instead you get a
washed out black color.
A typical character is formed by the drops.
As the resistor cools, the bubble collapses and the resulting suction pulls fresh ink from
the attached reservoir into the ink chamber. For color printing multiple cartridge of three
basic colors - Cyan, Magenta and Yellow are used. Color output of Inkjet printer is very
high quality, as ink is directly deposited on the paper. Most of good quality Inkjet printers
provide additional block cartridge other than three basic color cartridges. Mixing of three
basic colors to produce black gives very faded black color. Some Inkjet printers use
piezo-electric crystal to force the ink out of the chamber.
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Laser Printer
Electro photographic (EP) Print Process
The EP print process is the process by which an EP laser printer forms images on paper.
It consists of six major steps, each for a specific goal. Although many different
manufacturers call these steps different things or place them in a different order, the basic
process is still the same.
Here are the steps in the order you will see them on the exam:
1. Cleaning
2. Charging
3. Writing
4. Developing
5. Transferring
6. Fusing
Before any of these steps can begin, however, the controller must sense that the printer is
Ready to start printing (toner cartridge installed, fuser warmed to temperature, and all
covers in place). Printing cannot take place until the printer is in its ready state, usually
indicated by an illuminated Ready LED light or a display that says something like 00
READY (on HP printers).
STEP 1: CLEANING
In the first part of the laser print process, a rubber blade inside the EP cartridge scrapes
any toner left on the drum into a used toner receptacle inside the EP cartridge, and a
fluorescent lamp discharges any remaining charge on the photosensitive drum (remember
that the drum, being photosensitive, loses its charge when exposed to light). This step is
called the cleaning step The EP cartridge is constantly cleaning the drum. It may take
more than one rotation of the photosensitive drum to make an image on the paper. The
cleaning step keeps the drum fresh for each use. If you didn’t clean the drum, you would
see ghosts of previous pages printed along with your image.
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STEP 2: CHARGING
The next step in the EP process is the charging step .In this step, a special wirer roller
(called a charging corona) within the EP toner cartridge (above the photosensitive drum)
gets a high voltage from the HVPS. It uses this high voltage to apply a strong, uniform
negative charge (around –600VDC) to the surface of the photosensitive drum.
STEP 3: WRITING
Next is the writing step. In this step, the laser is turned on and scans the drum from side
to side, flashing on and off according to the bits of information the printer controller
sends it as it communicates the individual bits of the image. Wherever the laser beam
touches, the photosensitive drum’s charge is severely reduced from –600VDC to a slight
negative charge (around–100VDC). As the drum rotates, a pattern of exposed areas is
formed, representing the image to be printed..
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At this point, the controller sends a signal to the pickup roller to feed a piece of paper into
the printer, where it stops at the registration rollers.
STEP 4: DEVELOPING
Now that the surface of the drum holds an electrical representation of the image being
printed, its discrete electrical charges need to be converted into something that can be
transferred to apiece of paper. The EP process step that accomplishes this is the
developing step in this step; toner is transferred to the areas that were exposed in the
writing step. A metallic roller called the developing roller inside an EP cartridge acquires
a –600VDCcharge (called a bias voltage) from the HVPS. The toner sticks to this roller
because there is a magnet located inside the roller and because of the electrostatic charges
between the toner and the developing roller. While the developing roller rotates toward
the photosensitive drum, the toner acquires the charge of the roller (–600VDC). When the
toner comes between the developing roller and the photosensitive drum, the toner is
attracted to the areas that have been exposed by the laser (because these areas have a
lesser charge, of –100VDC). The toner also is repelled from the unexposed areas
(because they are at the same –600VDC charge, and like charges repel). This toner
transfer creates a fog of toner between the EP drum and the developing roller. The
photosensitive drum now has toner stuck to it where the laser has written. The
photosensitive drum continues to rotate until the developed image is ready to be
transferred to paper in the next step.
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STEP 5: TRANSFERRING
At this point in the EP process, the developed image is rotating into position. The
controller notifies the registration rollers that the paper should be fed through. The
registration rollers move the paper underneath the photosensitive drum, and the process
of transferring the image can begin, with the transferring step. The controller sends a
signal to the charging corona wire or roller (depending on which one the printer has) and
tells it to turn on. The corona wire/roller then acquires a strong positive charge
(+600VDC) and applies that charge to the paper. The paper, thus charged, pulls the toner
from the photosensitive drum at the line of contact between the roller and the paper,
because the paper and toner have opposite charges. Once the registration rollers move the
paper past the corona wire, the static-eliminator strip removes all charge from that line of
the paper. If the strip didn’t bleed this charge away, the paper would attract itself to the
toner cartridge and cause a paper jam. The toner is now held in place by weak
electrostatic charges and gravity. It will not stay there, however, unless it is made
permanent, which is the reason for the fusing step.
STEP 6: FUSING
In the final step, the fusing step, the toner image is made permanent. The registration
rollers push the paper toward the fuser rollers. Once the user grabs the paper, the
registration rollers push for only a short time more. The fuser is now in control of moving
the paper. As the paper passes through the fuser, the 350° F fuser roller melts the
polyester resin of the toner, and the rubberized pressure roller presses it permanently into
the paper the paper continues on through the fuser and eventually exits the printer. Once
the paper completely exits the fuser, it trips a sensor that tells the printer to finish the EP
process with the cleaning step. At this point, the printer can print another page, and the
EP process can begin again.
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Summary of the EP Print Process
First, the printer uses a rubber scraper to clean the photosensitive drum. Then the printer
places a uniform –600VDC charge on the photosensitive drum by means of a charging
corona. The laser “paints” an image onto the photosensitive drum, discharging the image
areas to a much lower voltage (–100VDC). The developing roller in the toner cartridge
has charged (–600VDC) toner stuck to it. As it rolls the toner toward the photosensitive
drum, the toner is attracted to (and sticks to) the areas of the photosensitive drum that the
laser has discharged. The image is then transferred from the drum to the paper at its line
of contact by means of the transfer corona wire (or corona roller) with a +600VDC
charge. The static-eliminator strip removes the high, positive charge from the paper, and
the paper, now holding the image, moves on. The paper then enters the fuser, where a
fuser roller and the pressure roller make the image permanent. The paper exits the printer,
and the printer begins printing the next page or returns to its ready state.
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Chapter - 8
Assembling a PC
We shell see how can assemble a prefect computer. Assembling computer is a very easy
job; just need select proper components and than connect them properly.
Material Required
Screwdriver set, Noseplier.
Required Computer Parts
Main case with power supply, Monitor, Keyboard, Mouse
Motherboard, Processor, Ram
Display card, Sound card, Modem card, and LAN card if Use
Floppy drive, Hard disk drive, CD-ROM Drive, DVD R/W
Speaker/ Microphone etc.
Following steps are required to assemble a P.C.
1. Remove Cover of the System Unit (Cabinet)
Open the four screws at the back of the system’s main unit.
Slide the top cover off the System Unit (Cabinet).
Remove Base Plate from the System Unit (Cabinet)
Remove the screws holding the base plate to the System Unit (Cabinet).
Lift the base plate out of the System Unit (Cabinet).
Mount the Motherboard to the plate
Place the motherboard on the base plate using the spacers and screws
provided.
Tighten the screws provided to fix the motherboard to the base plate.
Attach the Processor to the Motherboard.
Attach the CPU to the motherboard.
Attach CPU fan to the power connector (this is very impotent, as excessive
heat build up may permanently damage the processor).
Attach the RAM modules to the Motherboard.
To attach RAM modules, properly align both side of the module
With the slot given on the motherboard.
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Mount the Mother into the Computer Unit.
Once the CPU and memory is attached to the motherboard you can mount the
back plate (with the motherboard) into the main system unit.
Attach storage Devices to the main unit.
Place the FDD, HDD and CD-ROM etc.
Tighten the side holding screws only after power and data cable are attached.
Connect Cable and front Panel to the Motherboard.
Connect power cable to the motherboard if you have ATX Power supply
then the connector will fit in only one direction.
Attach various front panel connectors to the motherboard (reset, power/HDD
LED, Speaker, Power switch etc.)
Attach drive data cable power connectors to the Storage devices.
Connect primary IDE cable and power connector to the hard disk drive.
Connect secondary IDE cable and power connector to the CD Rom, DVD.
Connect floppy drive cable and power connector to the floppy drive.
Connect external port cable.
Connect serial, parallel, game, infrared etc. port to the motherboard.
Connectors for this are provided with the motherboard.
Connect Display card and Sound card.
To connect the cards finds an empty slot.
Insert the card by first aligning cards edge connectors to the slot on the
Motherboard.
Tighten the screw to fix the card to the Motherboard.
Connect CD Audio cable.
To use you CD Drive to hear Audio CDs, connect Audio out socket on the
CD/DVD drive to the CD in connector on the soundcard/motherboard (if the
motherboard has built in soundcard.)
The cable required to make this connection is generally provided with the
CD/DVD drive.
Connect peripherals.
Connect keyboard and mouse connectors provided at the back of the system.
If you have PS/2 keyboard and mouse to used connectors PS/2 of the system.
Connect External Cables.
Connect Data cable from the monitor to the back of the display connector.
Connect mains power cord to the system’s power supply.
Connect power cord from the monitor to the power supply.
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Check Connectors.
This is very important step before switching on the system. One should
carefully check all the cards and connectors.
Switch ON the system.
Turn the mains power on.
Switch supply/UPS etc. If are you using any.
Press the power on button on the front panel of the main system unit.
Configure BIOS.
Once things are working properly you can make changes in the BIOS setup to
make the system function in a better way.
Switch Off system and close system unit’s cover.
Before closing the cover, switch off the system.
Slide the cover on the system unit and fasten the screws at the back of the
unit.
Install the required software/programs.
Ones your machine is ready, you need to install the operating system
(Windows 98/NT/2000/ME/XP/Linux etc.) into your system
Once the operating system is installed, install the software required for your
work such as the Microsoft Office, Tally DTP software such as CorelDraw,
PageMaker, Photoshop, and Venture etc.
You can also install various regional Fonts, if your job requires it.
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Second Module
Operating System
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Categories of Software
System Software: System software consists of programs used to operate the computer.
They enable the machine to accept and sum other system or application programs. They
manage resources, extend facilities and control operations.
System software includes: -
Operating System
Assembler & Compliers.
System Utilities.
Utility Software: Utility programs or routines are prewritten programs to provide
procedures commonly required by virtually are applications.
Application Software: An application is design to handle a particular task required by
the end-user.
Disk Operating System (DOS)
Operating System & It’s Functions:
Operating system is a special program, which acts as an intermediate between the user
and the computer. It stats the computer to work accordance with the user.
Ex. Dos, Windows, Linux, UNIX etc.
Function:
1. Coordinate the input output device of a computer and provide a link between
them. So that data can transfer frequently.
2. It provides a prompt on the screen through which a user can interact with the
system.
3. It loads and executes the program in the memory.
4. It manages the data file on the disk.
5. Tells computer how to start and boot-up.
6. It manages bi-directional data transfer between disk and memory.
What is DOS?
DOS is nothing more than a large program that allows you to utilize the computer. It is
the first operating system developed by IBM and Micro-Soft.
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Types of DOS –
1. PC–DOS (Developed by IBM)
2. MS–DOS (Developed by Microsoft)
Resetting the computer –
The systems can restart again in two ways –
1. Warm Booting Ctrl+Alt+Del
2. Cold Booting Turn off the system.
Structure of DOS: Three main files –
The DOS operating system is composed of three main files accompanied by roughly 80
supporting files.
1. IO.SYS
2. MS-DOS.SYS
3. COMMAND.COM
1. IO.SYS
2.
Input output system file directly interact with computer Hardware. It reset disk system
and initialize attach devices. It contains some special software to support some input and
output devices (Device drives) which are use to control the operation of keyboard,
V.D.U. Disk controller etc. It forwards programs instruction to microprocessor to get the
processing done.
MS DOS .SYS
Interact directly with application program and IO.SYS file. It acts as a bridge between
application program and IO.SYS file. It handles bi-directional data transfer that is from
disk to memory and form memory to disk
Command.Com
It is command processor. It interacts with the user directly. It accepts the command given
by the user and interprets the command. So that the computer can understand it. Than
command compresses the instruction to the MS DOS.SYS file. It gives the prompt where
a user can type command. It also perform error checking and display error manages,
when error are detected.
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Drive Space Bin
It installs DOS in a compressive form.
Dos File & Name
File
A file a similar to a piece of paper in a file folder. In Dos, every file must have a file
name of up to eight characters in length.
File Name
Name. Extension
8 Characters. 3Characters
Never use these extensions for other type of files.
. Txt - Text file
. Sys - System file (it stores the information of the system)
. Com - Program file (it has command that can be executed)
. Exe.- Extension file
. Hlp - Help file.
. Bat - Batch file
Multi level Directories
A one directory can contain maximum of 255 file and directory. These directories may
also contain some of sub-directories. This organized file structure is called a multi-level
directory.
A Directory Contain following items
1. File name
2. Extension
3. File size.
4. Date Last Modify.
5. Time last Modify.
6. Starting location of the file on the disk.
7. Attributes
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Operating System
An operating system (commonly abbreviated as either OS or O/S) is an interface
between hardware and user. An OS is responsible for the management and coordination
of activities and the sharing of the resources of the computer. The operating system acts
as a host for computing applications run on the machine. As a host, one of the purposes
of an operating system is to handle the details of the operation of the hardware. This
relieves application programs from having to manage these details and makes it easier to
write applications. Almost all computers (including handheld computers, desktop
computers, supercomputers, video game consoles) as well as some robots, domestic
appliances (dishwashers, washing machines), and portable media players use an operating
system of some type. Some of the oldest models may however use an embedded
operating system, that may be contained on a compact disk or other data storage device.
Operating systems offer a number of services to application programs and users.
Applications access these services through application programming interfaces (APIs) or
system calls. By invoking these interfaces, the application can request a service from the
operating system, pass parameters, and receive the results of the operation. Users may
also interact with the operating system with some kind of software user interface (SUI)
like typing commands by using command line interface (CLI) or using a graphical user
interface (GUI, commonly pronounced “gooey”). For hand-held and desktop computers,
the user interface is generally considered part of the operating system. On large multiuser
systems like Unix and Unix-like systems, the user interface is generally
implemented as an application program that runs outside the operating system. (Whether
the user interface should be included as part of the operating system is a point of
contention.)
Common contemporary operating system families include BSD, Darwin (Mac OS X),
GNU/Linux, SunOS (Solaris/Open Solaris), and Windows NT (XP/Vista/7). While
servers generally run UNIX or some Unix-like operating system, embedded system
markets are split amongst several operating systems.
In the beginning
Proprietary operating systems were originally made to sell the company's hardware.
Without system software (compilers and operating systems), a budding hardware
developer had real difficulty launching a computer. The availability of operating systems
not tied to a single hardware supplier - such as Digital Research's CP/M for
microcomputers, and UNIX for larger computers - greatly transformed the computer
industry. Someone with an innovative idea could easily start producing hardware on
which buyers could use standard software. In 1969-70, UNIX first appeared on the PDP-
7 and later the PDP-11.
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It soon became capable of providing cross-platform time sharing using preemptive
multitasking, advanced memory management, memory protection, and a host of other
advanced features. UNIX soon gained popularity as an operating system for mainframes
and minicomputers alike. UNIX was inspired by Multicast, as were several other
operating systems, such as Data General's AOS-VS, and IBM's addition of such concepts
as subdirectories to PC DOS in version 2.0.
Microsoft bought QDOS from Seattle Computer Products, a very simple diskette
operating system somewhat similar to CP/M, to create an operating system, PC DOS, for
the launch of the IBM PC, under a deal with IBM where Microsoft could still sell the
operating system as MS DOS for non-IBM computers. Microsoft produced oddnumbered
major version numbers while IBM was responsible for even revision numbers
(2.0, 2.1, 4.0, etc) of the code base until version 6. There was very little difference
between MS-DOS and PC-DOS, one example being the inclusion of GW-BASIC with
MS-DOS (because some BASIC code in IBM PC ROMs was not legally allowed to be
put into non-IBM computers). MS-DOS and PC-DOS soon became known simply as
"DOS" (the term is now usually taken to also include other "DOSes" such as DR-DOS
and Free DOS, but it should not be confused with the command prompt program within
some operating systems, COMMAND.COM). Although MS-DOS could be tailored to
hardware significantly different to IBM's PC, it soon became common for hardware
vendors to make their equipment as compatible as possible with the IBM PC and its
immediate IBM successors (the PC-XT and later IBM PC-AT models), since many
popular DOS programs bypassed the operating system to access hardware directly for
speed, requiring other manufactures to closely copy the IBM design, including its
limitations. The availability of MS-DOS had two major effects on the computer industry:
the commercial acceptability of "sneaky tricks" (as documented, for example, in Ralf
Brown's Interrupt List) to gain speed or functionality or copy-protection, and a market
that demanded extreme compatibility (speed and cosmetic differences were the only
acceptable innovations).
IBM PC compatibles could also run Microsoft X enix, a UNIX-like operating system
from the early 1980s. XENIX was heavily marketed by Microsoft as a multi-user
alternative to its single user MS-DOS operating system. The CPUs of these personal
computers could not facilitate kernel memory protection or provide dual mode operation,
so XENIX relied on cooperative multitasking and had no protected memory.
The 80286-based IBM PC AT was the first IBM compatible personal computer capable
of providing protected memory mode operation. However, this mode was hampered by
software bugs in its implementation on the 286, and not widely accepted until the release
of the Intel 80386. With the 386 porting BSD Unix to a PC became feasible, and various
Unix-like systems (tagged "*nix" at the time), including Linux, arose, but IBM (and,
initially, Microsoft) opted for OS/2 from the inception of the PS/2; Microsoft eventually
going its own way with Microsoft Windows firstly as a GUI on top of DOS, then as a
complete operating system.
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Classic Mac OS, and Microsoft Windows 1.0-3.11 supported only cooperative
multitasking (Windows 95, 98, & ME supported preemptive multitasking only when
running 32-bit applications, but ran legacy 16-bit applications using cooperative
multitasking), and were very limited in their abilities to take advantage of protected
memory. Application programs running on these operating systems must yield CPU time
to the scheduler when they are not using it, either by default, or by calling a function.
Windows NT's underlying operating system kernel which was designed by essentially the
same team as Digital Equipment Corporation's VMS, a UNIX-like operating system
which provided protected mode operation for all user programs, kernel memory
protection, preemptive multi-tasking, virtual file system support, and a host of other
features.
Classic Amiga OS and versions of Microsoft Windows from Windows 1.0 through
Windows Me did not properly track resources allocated by processes at runtime.[citation
needed] If a process had to be terminated, the resources might not be freed up for new
programs until the machine was restarted.
The Amiga OS did have preemptive multitasking, as did operating systems for many
larger ("supermini") computers that, despite being technically better, were struggling in
sales when faced with the mass production of increasingly-faster "Personal" Computers
and customers locked into non-portable software (legacy software and proprietary office
documents).
Mainframes
Through the 1950s, many major features were pioneered in the field of operating
systems. The development of the IBM System/360 produced a family of mainframe
computers available in widely differing capacities and price points, for which a single
operating system OS/360 was planned (rather than developing ad-hoc programs for every
individual model). This concept of a single OS spanning an entire product line was
crucial for the success of System/360 and, in fact, IBM`s current mainframe operating
systems are distant descendants of this original system; applications written for the
OS/360 can still be run on modern machines. In the mid-70, the MVS, the descendant of
OS/360 offered the firs implementation of using RAM as a transparent cache for data.
OS/360 also pioneered a number of concepts that, in some cases, are still not seen outside
of the mainframe arena. For instance, in OS/360, when a program is started, the operating
system keeps track of all of the system resources that are used including storage, locks,
data files, and so on. When the process is terminated for any reason, all of these resources
are re-claimed by the operating system. An alternative CP-67 system started a whole line
of operating systems focused on the concept of virtual machines.
Control Data Corporation developed the SCOPE operating system in the 1960s, for batch
processing. In cooperation with the University of Minnesota, the KRONOS and later the
NOS operating systems were developed during the 1970s, which supported simultaneous
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batch and timesharing use. Like many commercial timesharing systems, its interface was
an extension of the Dartmouth BASIC operating systems, one of the pioneering efforts in
timesharing and programming languages. In the late 1970s, Control Data and the
University of Illinois developed the PLATO operating system, which used plasma panel
displays and long-distance time sharing networks. Plato was remarkably innovative for its
time, featuring real-time chat, and multi-user graphical games. Burroughs Corporation
introduced the B5000 in 1961 with the MCP, (Master Control Program) operating
system. The B5000 was a stack machine designed to exclusively support high-level
languages with no machine language or assembler, and indeed the MCP was the first OS
to be written exclusively in a high-level language – ESPOL, a dialect of ALGOL. MCP
also introduced many other ground-breaking innovations, such as being the first
commercial implementation of virtual memory. During development of the AS400, IBM
made an approach to Burroughs to license MCP to run on the AS400 hardware. This
proposal was declined by Burroughs management to protect its existing hardware
production. M CP is still in use today in the Unisys Clear Path /MCP line of computers.
UNIVAC, the first commercial computer manufacturer, produced a series of EXEC
operating systems. Like all early main-frame systems, this was a batch-oriented system
that managed magnetic drums, disks, card readers and line printers. In the 1970s,
UNIVAC produced the Real-Time Basic (RTB) system to support large-scale time
sharing, also patterned after the Dartmouth BASIC system.
General Electric and MIT developed General Electric Comprehensive Operating
Supervisor (GECOS), which introduced the concept of ringed security privilege levels.
After acquisition by Honeywell it was renamed to General Comprehensive Operating
System (GCOS).
Digital Equipment Corporation developed many operating systems for its various
computer lines, including TOPS-10 and TOPS-20 time sharing systems for the 36-bit
PDP-10 class systems. Prior to the widespread use of UNIX, TOPS-10 was a particularly
popular system in universities, and in the early ARPANET community.
In the late 1960s through the late 1970s, several hardware capabilities evolved that
allowed similar or ported software to run on more than one system. Early systems had
utilized microprogramming to implement features on their systems in order to permit
different underlying architecture to appear to be the same as others in a series. In fact
most 360's after the 360/40 (except the 360/165 and 360/168) were micro programmed
implementations. But soon other means of achieving application compatibility were
proven to be more significant.
The enormous investment in software for these systems made since 1960s caused most of
the original computer manufacturers to continue to develop compatible operating systems
along with the hardware. The notable supported mainframe operating systems include:
Burroughs MCP – B5000, 1961 to Unisys Clear path/MCP, present.
IBM OS/360 – IBM System/360, 1966 to IBM z/OS, present.
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IBM CP-67 – IBM System/360, 1967 to IBM z/VM, present.
UNIVAC EXEC 8 – UNIVAC 1108, 1967, to OS 2200 Unisys Clear path
Dorado, present.
Microcomputers
The first microcomputers did not have the capacity or need for the elaborate operating
systems that had been developed for mainframes and minis; minimalist operating systems
were developed, often loaded from ROM and known as Monitors. One notable early
disk-based operating system was CP/M, which was supported on many early
microcomputers and was closely imitated in MS-DOS, which became wildly popular as
the operating system chosen for the IBM PC (IBM's version of it was called IBM DOS or
PC DOS), its successors making Microsoft. In the 80's Apple Computer Inc. (now Apple
Inc.) abandoned its popular Apple II series of microcomputers to introduce the Apple
Macintosh computer with an innovative Graphical User Interface (GUI) to the Mac OS.
The introduction of the Intel 80386 CPU chip with 32-bit architecture and paging
capabilities, provided personal computers with the ability to run multitasking operating
systems like those of earlier mini computer
Uters and mainframes. Microsoft responded to this progress by hiring Dave Cutler, who
had developed the VMS operating system for Digital Equipment Corporation. He would
lead the development of the Windows NT operating system, which continues to serve as
the basis for Microsoft's operating systems line. Steve Jobs, a co-founder of Apple Inc.,
started NeXT Computer Inc., which developed the Unix-like NEXTSTEP operating
system. NEXTSTEP would later be acquired by Apple Inc. and used, along with code
from FreeBSD as the core of Mac OS X.
Minix, an academic teaching tool which could be run on early PCs, would inspire
another reimplementation of U nix, called Linux. Started by computer science student
Linus Torvalds with cooperation from volunteers over the internet, a operating system
was developed with the tools from the GNU Project. The Berkeley Software Distribution,
known as BSD, is the UNIX derivative distributed by the University of California,
Berkeley, starting in the 1970s. Freely distributed and ported to many minicomputers, it
eventually also gained a following for use on PCs, mainly as FreeBSD, NetBSD and
Open BSD.
Features
Program execution
The operating system acts as an interface between an application and the hardware. The
user interacts with the hardware from "the other side". The operating system is a set of
services which simplifies development of applications. Executing a program involves the
creation of a process by the operating system. The kernel creates a process by assigning
memory and other resources, establishing a priority for the process (in multi-tasking
systems), loading program code into memory, and executing the program. The program
then interacts with the user and/or other devices and performs its intended function.
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Interrupts
Interrupts are central to operating systems, since they provide an efficient way for the
operating system to interact with and react to its environment. The alternative—having
the operating system "watch" the various sources of input for events (polling) that require
action—is a poor use of CPU resources. Interrupt-based programming is directly
supported by most CPUs. Interrupts provide a computer with a way of automatically
running specific code in response to events. Even very basic computers support hardware
interrupts, and allow the programmer to specify code which may be run when that event
takes place.
When an interrupt is received, the computer's hardware automatically suspends whatever
program is currently running, saves its status, and runs computer code previously
associated with the interrupt; this is analogous to placing a bookmark in a book in
response to a phone call. In modern operating systems, interrupts are handled by the
operating system's kernel. Interrupts may come from either the computer's hardware or
from the running program.
When a hardware device triggers an interrupt the operating system's kernel decides how
to deal with this event, generally by running some processing code. How much code gets
run depends on the priority of the interrupt (for example: a person usually responds to a
smoke detector alarm before answering the phone). The processing of hardware interrupts
is a task that is usually delegated to software called device drivers, which may be either
part of the operating system's kernel, part of another program, or both. Device drivers
may then relay information to a running program by various means.
A program may also trigger an interrupt to the operating system. If a program wishes to
access hardware for example, it may interrupt the operating system's kernel, which causes
control to be passed back to the kernel. The kernel will then process the request. If a
program wishes additional resources (or wishes to shed resources) such as memory, it
will trigger an interrupt to get the kernel's attention.
Protected mode and supervisor mode
Modern CPUs support something called dual mode operation. CPUs with this capability
use two modes: protected mode and supervisor mode, which allow certain CPU functions
to be controlled and affected only by the operating system kernel. Here, protected mode
does not refer specifically to the 80286 (Intel's x86 16-bit microprocessor) CPU feature,
although its protected mode is very similar to it. CPUs might have other modes similar to
80286 protected mode as well, such as the virtual 8086 mode of the 80386 (Intel's x86
32-bit microprocessor or i386).
However, the term is used here more generally in operating system theory to refer to all
modes which limit the capabilities of programs running in that mode, providing things
like virtual memory addressing and limiting access to hardware in a manner determined
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by a program running in supervisor mode. Similar modes have existed in supercomputers,
minicomputers, and mainframes as they are essential to fully supporting UNIX-like
multi-user operating systems.
When a computer first starts up, it is automatically running in supervisor mode. The first
few programs to run on the computer, being the BIOS, boot loader and the operating
system have unlimited access to hardware - and this is required because, by definition,
initializing a protected environment can only be done outside of one. However, when the
operating system passes control to another program, it can place the CPU into protected
mode.
In protected mode, programs may have access to a more limited set of the CPU's
instructions. A user program may leave protected mode only by triggering an interrupt,
causing control to be passed back to the kernel. In this way the operating system can
maintain exclusive control over things like access to hardware and memory.
The term "protected mode resource" generally refers to one or more CPU registers, which
contain information that the running program isn't allowed to alter. Attempts to alter
these resources generally cause a switch to supervisor mode, where the operating system
can deal with the illegal operation the program was attempting (for example, by killing
the program).
Memory management
Among other things, a multiprogramming operating system kernel must be responsible
for managing all system memory which is currently in use by programs. This ensures that
a program does not interfere with memory already used by another program. Since
programs time share, each program must have independent access to memory.
Cooperative memory management, used by many early operating systems assumes that
all programs make voluntary use of the kernel's memory manager, and do not exceed
their allocated memory. This system of memory management is almost never seen
anymore, since programs often contain bugs which can cause them to exceed their
allocated memory. If a program fails it may cause memory used by one or more other
programs to be affected or overwritten. Malicious programs, or viruses may purposefully
alter another program's memory or may affect the operation of the operating system
itself. With cooperative memory management it takes only one misbehaved program to
crash the system.
Memory protection enables the kernel to limit a process' access to the computer's
memory. Various methods of memory protection exist, including memory segmentation
and paging. All methods require some level of hardware support (such as the 80286
MMU) which doesn't exist in all computers.
In both segmentation and paging, certain protected mode registers specify to the CPU
what memory address it should allow a running program to access. Attempts to access
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other addresses will trigger an interrupt which will cause the CPU to re-enter supervisor
mode, placing the kernel in charge. This is called a segmentation violation or Seg-V for
short, and since it is both difficult to assign a meaningful result to such an operation, and
because it is usually a sign of a misbehaving program, the kernel will generally resort to
terminating the offending program, and will report the error.
Windows 3.1-Me had some level of memory protection, but programs could easily
circumvent the need to use it. Under Windows 9x all MS-DOS applications ran in
supervisor mode, giving them almost unlimited control over the computer. A general
protection fault would be produced indicating a segmentation violation had occurred,
however the system would often crash anyway.
In most Linux systems, part of the hard disk is reserved for virtual memory when the
Operating system is being installed on the system. This part is known as swap space.
Windows systems use a swap file instead of a partition.
Virtual memory
The use of virtual memory addressing (such as paging or segmentation) means that the
kernel can choose what memory each program may use at any given time, allowing the
operating system to use the same memory locations for multiple tasks.
If a program tries to access memory that isn't in its current range of accessible memory,
but nonetheless has been allocated to it, the kernel will be interrupted in the same way as
it would if the program were to exceed its allocated memory. (See section on memory
management.) Under UNIX this kind of interrupt is referred to as a page fault.
When the kernel detects a page fault it will generally adjust the virtual memory range of
the program which triggered it, granting it access to the memory requested. This gives the
kernel discretionary power over where a particular application's memory is stored, or
even whether or not it has actually been allocated yet.
In modern operating systems, memory which is accessed less frequently can be
temporarily stored on disk or other media to make that space available for use by other
programs. This is called swapping, as an area of memory can be used by multiple
programs, and what that memory area contains can be swapped or exchanged on demand.
Multitasking
Multitasking refers to the running of multiple independent computer programs on the
same computer; giving the appearance that it is performing the tasks at the same time.
Since most computers can do at most one or two things at one time, this is generally done
via time sharing, which means that each program uses a share of the computer's time to
execute.
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An operating system kernel contains a piece of software called a scheduler which
determines how much time each program will spend executing, and in which order
execution control should be passed to programs. Control is passed to a process by the
kernel, which allows the program access to the CPU and memory. At a later time control
is returned to the kernel through some mechanism, so that another program may be
allowed to use the CPU. This so-called passing of control between the kernel and
applications is called a context switch.
An early model which governed the allocation of time to programs was called
cooperative multitasking. In this model, when control is passed to a program by the
kernel, it may execute for as long as it wants before explicitly returning control to the
kernel. This means that a malicious or malfunctioning program may not only prevent any
other programs from using the CPU, but it can hang the entire system if it enters an
infinite loop.
The philosophy governing preemptive multitasking is that of ensuring that all programs
are given regular time on the CPU. This implies that all programs must be limited in how
much time they are allowed to spend on the CPU without being interrupted. To
accomplish this, modern operating system kernels make use of a timed interrupt. A
protected mode timer is set by the kernel which triggers a return to supervisor mode after
the specified time has elapsed. (See above sections on Interrupts and Dual Mode
Operation.)
On many single user operating systems cooperative multitasking is perfectly adequate, as
home computers generally run a small number of well tested programs. Windows NT was
the first version of Microsoft Windows which enforced preemptive multitasking, but it
didn't reach the home user market until Windows XP, (since Windows NT was targeted
at professionals.)
Kernel preemption
In recent years, concerns have arisen because of long latencies associated with some
kernel run-times, sometimes on the order of 100ms or more in systems with monolithic
kernels. These latencies often produce noticeable slowness in desktop systems, and can
prevent operating systems from performing time-sensitive operations such as audio
recording and some communications.
Modern operating systems extend the concepts of application preemption to device
drivers and kernel code, so that the operating system has preemptive control over internal
run-times as well. Under Windows Vista, the introduction of the Windows Display
Driver Model (WDDM) accomplishes this for display drivers, and in Linux, the preempt
able kernel model introduced in version 2.6 allows all device drivers and some other parts
of kernel code to take advantage of preemptive multi-tasking.
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Under Windows prior to Windows Vista and Linux prior to version 2.6 all driver
execution was co-operative, meaning that if a driver entered an infinite loop it would
freeze the system.
Disk access and file systems
Access to data stored on disks is a central feature of all operating systems. Computers
store data on disks using files, which are structured in specific ways in order to allow for
faster access, higher reliability, and to make better use out of the drive's available space.
The specific way in which files are stored on a disk is called a file system, and enables
files to have names and attributes. It also allows them to be stored in a hierarchy of
directories or folders arranged in a directory tree.
Early operating systems generally supported a single type of disk drive and only one kind
of file system. Early file systems were limited in their capacity, speed, and in the kinds of
file names and directory structures they could use. These limitations often reflected
limitations in the operating systems they were designed for, making it very difficult for
an operating system to support more than one file system.
While many simpler operating systems support a limited range of options for accessing
storage systems, operating systems like UNIX and Linux support a technology known as
a virtual file system or VFS. An operating system like UNIX supports a wide array of
storage devices, regardless of their design or file systems to be accessed through a
common app lication programming interface (API). This makes it unnecessary for
programs to have any knowledge about the device they are accessing. A VFS allows the
operating system to provide programs with access to an unlimited number of devices with
an infinite variety of file systems installed on them through the use of specific device
drivers and file system drivers.
A connected storage device such as a hard drive is accessed through a device driver. The
device driver understands the specific language of the drive and is able to translate that
language into a standard language used by the operating system to access all disk drives.
On UNIX this is the language of block devices.
When the kernel has an appropriate device driver in place, it can then access the contents
of the disk drive in raw format, which may contain one or more file systems. A file
system driver is used to translate the commands used to access each specific file system
into a standard set of commands that the operating system can use to talk to all file
systems. Programs can then deal with these files systems on the basis of filenames, and
directories/folders, contained within a hierarchical structure. They can create, delete,
open, and close files, as well as gather various information about them, including access
permissions, size, and free space, and creation and modification dates.
Various differences between file systems make supporting all file systems difficult.
Allowed characters in file names, case sensitivity, and the presence of various kinds of
file attributes makes the implementation of a single interface for every file system a
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daunting task. Operating systems tend to recommend the use of (and so support natively)
file systems specifically designed for them; for example, NTFS in Windows and ext3 and
Reiser FS in Linux. However, in practice, third party drives are usually available to give
support for the most widely used file systems in most general-purpose operating systems
(for example, NTFS is available in Linux through NTFS-3g, and ext2/3 and Reiser FS are
available in Windows through FSdriver and rfstool).
Device drivers
A device driver is a specific type of computer software developed to allow interaction
with hardware devices. Typically this constitutes an interface for communicating with the
device, through the specific computer bus or communications subsystem that the
hardware is connected to, providing commands to and/or receiving data from the device,
and on the other end, the requisite interfaces to the operating system and software
applications. It is a specialized hardware-dependent computer program which is also
operating system specific that enables another program, typically an operating system or
applications software package or computer program running under the operating system
kernel, to interact transparently with a hardware device, and usually provides the requisite
interrupt handling necessary for any necessary asynchronous time-dependent hardware
interfacing needs.
The key design goal of device drivers is abstraction. Every model of hardware (even
within the same class of device) is different. Newer models also are released by
manufacturers that provide more reliable or better performance and these newer models
are often controlled differently. Computers and their operating systems cannot be
expected to know how to control every device, both now and in the future. To solve this
problem, OSes essentially dictate how every type of device should be controlled. The
function of the device driver is then to translate these OS mandated function calls into
device specific calls. In theory a new device, which is controlled in a new manner, should
function correctly if a suitable driver is available. This new driver will ensure that the
device appears to operate as usual from the operating systems' point of view.
Networking
Currently most operating systems support a variety of networking protocols, hardware,
and applications for using them. This means that computers running dissimilar operating
systems can participate in a common network for sharing resources such as computing,
files, printers, and scanners using either wired or wireless connections. Networks can
essentially allow a computer's operating system to access the resources of a remote
computer to support the same functions as it could if those resources were connected
directly to the local computer. This includes everything from simple communication, to
using networked file systems or even sharing another computer's graphics or sound
hardware. Some network services allow the resources of a computer to be accessed
transparently, such as SSH which allows networked users direct access to a computer's
command line interface.
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Client/server networking involves a program on a computer somewhere which connects
via a network to another computer, called a server. Servers, usually running UNIX or
Linux, offer (or host) various services to other network computers and users. These
services are usually provided through ports or numbered access points beyond the
server's network address. Each port number is usually associated with a maximum of one
running program, which is responsible for handling requests to that port. A daemon,
being a user program, can in turn access the local hardware resources of that computer by
passing requests to the operating system kernel.
Many operating systems support one or more vendor-specific or open networking
protocols as well, for example, SNA on IBM systems, DE Cent on systems from Digital
Equipment Corporation, and Microsoft-specific protocols (SMB) on Windows. Specific
protocols for specific tasks may also be supported such as NFS for file access. Protocols
like E sound, or esd can be easily extended over the network to provide sound from local
applications, on a remote system's sound hardware.
Security
A computer being secure depends on a number of technologies working properly. A
modern operating system provides access to a number of resources, which are available
to software running on the system, and to external devices like networks via the kernel.
The operating system must be capable of distinguishing between requests which should
be allowed to be processed, and others which should not be processed. While some
systems may simply distinguish between "privileged" and "non-privileged", systems
commonly have a form of requester identity, such as a user name. To establish identity
there may be a process of authentication. Often a username must be quoted, and each
username may have a password. Other methods of authentication, such as magnetic cards
or biometric data, might be used instead. In some cases, especially connections from the
network, resources may be accessed with no authentication at all (such as reading files
over a network share). Also covered by the concept of requester identity is authorization;
the particular services and resources accessible by the requester once logged into a
system and tied to either the requester's user account or to the variously configured
groups of users to which the requester belongs.
In addition to the allow/disallow model of security, a system with a high level of security
will also offer auditing options. These would allow tracking of requests for access to
resources (such as, "who has been reading this file?"). Internal security or security from
an already running program is only possible if all possibly harmful requests must be
carried out through interrupts to the operating system kernel. If programs can directly
access hardware and resources, they cannot be secured.
External security involves a request from outside the computer, such as a login at a
connected console or some kind of network connection. External requests are often
passed through device drivers to the operating system's kernel, where they can be passed
onto applications, or carried out directly. Security of operating systems has long been a
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concern because of highly sensitive data held on computers, both of a commercial and
military nature. The United States Government Department of Defense (DoD) created the
Trusted Computer System Evaluation Criteria (TCSEC) which is a standard that sets
basic requirements for assessing the effectiveness of security. This became of vital
importance to operating system makers, because the TCSEC was used to evaluate,
classify and select computer systems being considered for the processing, storage and
retrieval of sensitive or classified information.
Network services include offerings such as file sharing, print services, email, web sites,
and file transfer protocols (FTP), most of which can have compromised security. At the
front line of security are hardware devices known as firewalls or intrusion
detection/prevention systems. At the operating system level, there are a number of
software firewalls available, as well as intrusion detection/prevention systems. Most
modern operating systems include a software firewall, which is enabled by default. A
software firewall can be configured to allow or deny network traffic to or from a service
or application running on the operating system. Therefore, one can install and be running
an insecure service, such as Telnet or FTP, and not have to be threatened by a security
breach because the firewall would deny all traffic trying to connect to the service on that
port.
An alternative strategy, and the only sandbox strategy available in systems that do not
meet the Popek and Goldberg virtualization requirements, is the operating system not
running user programs as native code, but instead either emulates a processor or provides
a host for a p-code based system such as Java.
Internal security is especially relevant for multi-user systems; it allows each user of the
system to have private files that the other users cannot tamper with or read. Internal
security is also vital if auditing is to be of any use, since a program can potentially bypass
the operating system, inclusive of bypassing auditing.
Microsoft Windows
While the Windows 9x series offered the option of having profiles for multiple users,
they had no concept of access privileges, and did not allow concurrent access; and so
were not true multi-user operating systems. In addition, they implemented only partial
memory protection. They were accordingly widely criticized for lack of security.
The Windows NT series of operating systems, by contrast, are true multi-user, and
implement absolute memory protection. However, a lot of the advantages of being a true
multi-user operating system were nullified by the fact that, prior to Windows Vista, the
first user account created during the setup process was an administrator account, which
was also the default for new accounts. Though Windows XP did have limited accounts,
the majority of home users did not change to an account type with fewer rights – partially
due to the number of programs which unnecessarily required administrator rights – and
so most home users ran as administrator all the time.
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Windows Vista changes this by introducing a privilege elevation system called User
Account Control. When logging in as a standard user, a logon session is created and a
token containing only the most basic privileges is assigned. In this way, the new logon
session is incapable of making changes that would affect the entire system. When logging
in as a user in the Administrators group, two separate tokens are assigned. The first token
contains all privileges typically awarded to an administrator, and the second is a restricted
token similar to what a standard user would receive. User applications, including the
Windows Shell, are then started with the restricted token, resulting in a reduced privilege
environment even under an Administrator account. When an application requests higher
privileges or "Run as administrator" is clicked, UAC will prompt for confirmation and, if
consent is given (including administrator credentials if the account requesting the
elevation is not a member of the administrators group), start the process using the
unrestricted token.
Linux/Unix
Linux and UNIX both have two tier securities, which limit any system-wide changes to
the root user, a special user account on all UNIX-like systems. While the root user has
virtually unlimited permission to effect system changes, programs running as a regular
user are limited in where they can save files, what hardware they can access, etc. In many
systems, a user's memory usage, their selection of available programs, their total disk
usage or quota, available range of programs' priority settings, and other functions can also
be locked down. This provides the user with plenty of freedom to do what needs to be
done, without being able to put any part of the system in jeopardy (barring accidental
triggering of system-level bugs) or make sweeping, system-wide changes. The user's
settings are stored in an area of the computer's file system called the user's home
directory, which is also provided as a location where the user may store their work, a
concept later adopted by Windows as the 'My Documents' folder. Should a user have to
install software outside of his home directory or make system-wide changes, they must
become the root user temporarily, usually with the su or sudo command, which is
answered with the computer's root password when prompted. Some systems (such as
Ubuntu and its derivatives) are configured by default to allow select users to run
programs as the root user via the sudo command, using the user's own password for
authentication instead of the system's root password. One is sometimes said to "go root"
or "drop to root" when elevating oneself to root access.
File system support in modern operating systems
Support for file systems is highly varied among modern operating systems although there
are several common file systems which almost all operating systems include support and
drivers for.
Solaris
The Solaris Operating System (as with most operating systems based upon open
standards and/or open source) uses UFS as its primary file system. Prior to 1998, Solaris
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UFS did not have logging/journaling capabilities, but over time the OS has gained this
and other new data management capabilities.
Additional features include Vertis (Journaling) Vx FS, QFS from Sun Microsystems,
enhancements to UFS including multiyear byte support and UFS volume management
included as part of the OS, and ZFS (open source, pool able, 128-bit, compressible, and
error-correcting).
Kernel extensions were added to Solaris to allow for bootable VERITAS Vexes
operation. Logging or journaling was added to UFS in Solaris 7. Releases of Solaris 10,
Solaris Express, Open Solaris, and other open source variants of Solaris later supported
bootable ZFS.
Logical Volume Management allows for spanning a file system across multiple devices
for the purpose of adding redundancy, capacity, and/or throughput. Solaris includes
Solaris Volume Manager (formerly known as Solstice Disk Suite.) Solaris is one of many
operating systems supported by VERITAS Volume Manager. Modern Solaris based
operating systems eclipse the need for volume management through leveraging virtual
storage pools in ZFS.
Linux
Many Linux distributions support some or all of ext2, ext3, ext4, Reiser FS, Reiser4, JFS
, XFS , GFS, GFS2, OCFS, OCFS2, and NILFS. The ext file systems, namely ext2, ext3
and ext4 are based on the original Linux file system. Others have been developed by
companies to meet their specific needs, hobbyists, or adapted from UNIX, Microsoft
Windows, and other operating systems. Linux has full support for XFS and JFS, along
with FAT (the MS-DOS file system), and HFS which is the primary file system for the
Macintosh.
In recent years support for Microsoft Windows NT's NTFS file system has appeared in
Linux, and is now comparable to the support available for other native UNIX file
systems. ISO 9660 and Universal Disk Format (UDF) are supported which are standard
file systems used on CDs, DVDs, and Blu Ray discs. It is possible to install Linux on the
majority of these file systems. Unlike other operating systems, Linux and UNIX allow
any file system to be used regardless of the media it is stored in, whether it is a hard
drive, a disc (CD,DVD...), an USB key, or even contained within a file located on another
file system.
Microsoft Windows
Microsoft Windows currently supports NTFS and FAT file systems, along with network
file systems shared from other computers, and the ISO 9660 and UDF file systems used
for CDs, DVDs, and other optical discs such as Blu-ray. Under Windows each file system
is usually limited in application to certain media, for example CDs must use ISO 9660 or
UDF, and as of Windows Vista, NTFS is the only file system which the operating system
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can be installed on. Windows Embedded CE 6.0, Windows Vista Service Pack 1, and
Windows Server 2008 support Ex FAT, a file system more suitable for flash drives.
Mac OS X
Mac OS X supports HFS+ with journaling as its primary file system. It is derived from
the Hierarchical File System of the earlier Mac OS. Mac OS X has facilities to read and
write FAT, NTFS (read-only, although an open-source cross platform implementation
known as NTFS 3G provides read-write support to Microsoft Windows NTFS file system
for Mac OS X users), UDF, and other file systems, but cannot be installed to them. Due
to its UNIX heritage Mac OS X now supports virtually all the file systems supported by
the UNIX VFS. Recently Apple Inc. started work on porting Sun Microsystems' ZFS file
system to Mac OS X and preliminary support is already available in Mac OS X 10.5 as
well as support for Blu-ray discs.
Special-purpose file systems
FAT file systems are commonly found on floppy disks, flash memory cards, digital
cameras, and many other portable devices because of their relative simplicity.
Performance of FAT compares poorly to most other file systems as it uses overly
simplistic data structures, making file operations time-consuming, and makes poor use of
disk space in situations where many small files are present. ISO 9660 and Universal Disk
Format are two common formats that target Compact Discs and DVDs. Mount Rainier is
a newer extension to UDF supported by Linux 2.6 series and Windows Vista that
facilitates rewriting to DVDs in the same fashion as has been possible with floppy disks.
Journalized file systems
File systems may provide journaling, which provides safe recovery in the event of a
system crash. A journeyed file system writes some information twice: first to the journal,
which is a log of file system operations, then to its proper place in the ordinary file
system. Journaling is handled by the file system driver, and keeps track of each operation
taking place that changes the contents of the disk. In the event of a crash, the system can
recover to a consistent state by replaying a portion of the journal. Many UNIX file
systems provide journaling including ReiserFS, JFS, and Ext3.
In contrast, non-journeyed file systems typically need to be examined in their entirety by
a utility such as fsck or chkdsk for any inconsistencies after an unclean shutdown. Soft
updates is an alternative to journaling that avoids the redundant writes by carefully
ordering the update operations. Log-structured file systems and ZFS also differ from
traditional journeyed file systems in that they avoid inconsistencies by always writing
new copies of the data, eschewing in-place updates.
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Graphical user interfaces
Most of the modern computer systems support graphical user interfaces (GUI), and often
include them. In some computer systems, such as the original implementations of
Microsoft Windows and the Mac OS, the GUI is integrated into the kernel.
While technically a graphical user interface is not an operating system service,
incorporating support for one into the operating system kernel can allow the GUI to be
more responsive by reducing the number of context switches required for the GUI to
perform its output functions. Other operating systems are modular, separating the
graphics subsystem from the kernel and the Operating System. In the 1980s UNIX, VMS
and many others had operating systems that were built this way. Linux and Mac OS X are
also built this way. Modern releases of Microsoft Windows such as Windows Vista
implement a graphics subsystem that is mostly in user-space; however versions between
Windows NT 4.0 and Windows Server 2003's graphics drawing routines exist mostly in
kernel space. Windows 9x had very little distinction between the interface and the kernel.
Many computer operating systems allow the user to install or create any user interface
they desire. The X Window System in conjunction with GNOME or KDE is a
commonly-found setup on most UNIX and UNIX-like (BSD, Linux, Minix) systems. A
number of Windows shell replacements have been released for Microsoft Windows,
which offer alternatives to the included Windows shell, but the shell itself cannot be
separated from Windows.
Numerous Unix-based GUIs have existed over time, most derived from X11.
Competition among the various vendors of UNIX (HP, IBM, and Sun) led to much
fragmentation, though an effort to standardize in the 1990s to COSE and CDE failed for
the most part due to various reasons, eventually eclipsed by the widespread adoption of
GNOME and KDE. Prior to open source-based toolkits and desktop environments, Motif
was the prevalent toolkit/desktop combination (and was the basis upon which CDE was
developed).
Graphical user interfaces evolve over time. For example, Windows has modified its user
interface almost every time a new major version of Windows is released, and the Mac OS
GUI changed dramatically with the introduction of Mac OS X in 1999.
Microsoft Windows
Microsoft Windows is a family of proprietary operating systems that originated as an
add-on to the older MS-DOS operating system for the IBM PC. Modern versions are
based on the newer Windows NT kernel that was originally intended for OS/2. Windows
runs on x86, x86-64 and Itanium processors. Earlier versions also ran on the DEC Alpha,
MIPS, Fairchild (later Intergraph) Clipper and PowerPC architectures (some work was
done to port it to the SPARC architecture).
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As of June 2008, Microsoft Windows holds a large amount of the worldwide desktop
market share. Windows is also used on servers, supporting applications such as web
servers and database servers. In recent years, Microsoft has spent significant marketing
and research & development money to demonstrate that Windows is capable of running
any enterprise application, which has resulted in consistent price/performance records
(see the TPC) and significant acceptance in the enterprise market.
The most widely used version of the Microsoft Windows family is Windows XP, released
on October 25, 2001.
In November 2006, after more than five years of development work, Microsoft released
Windows Vista, a major new operating system version of Microsoft Windows family
which contains a large number of new features and architectural changes. Chief amongst
these are a new user interface and visual style called Windows Aero, a number of new
security features such as User Account Control, and a few new multimedia applications
such as Windows DVD Maker. A server variant based on the same kernel, Windows
Server 2008, was released in early 2008.
Windows 7 is currently under development; Microsoft has stated that it intends to scope
its development to a three-year timeline; it is to be released on October 22, 2009.
Unix and unix-like operating systems
Debian is a (Linux-based) UNIX-like system
Ken Thompson wrote B, mainly based on BCPL, which he used to write UNIX, based on
his experience in the MULTICS project. B was replaced by C, and Unix developed into a
large, complex family of inter-related operating systems which have been influential in
every modern operating system .The Unix-like family is a diverse group of operating
systems, with several major sub-categories including System V, BSD, and Linux. The
name "UNIX" is a trademark of The Open Group which licenses it for use with any
operating system that has been shown to conform to their definitions. "Unix-like" is
commonly used to refer to the large set of operating systems which resemble the original
UNIX.
Unix-like systems run on a wide variety of machine architectures. They are used heavily
for servers in business, as well as workstations in academic and engineering
environments. Free UNIX variants, such as GNU, Linux and BSD, are popular in these
areas.
Some UNIX variants like HP's HP-UX and IBM's AIX are designed to run only on that
vendor's hardware. Others, such as Solaris, can run on multiple types of hardware,
including x86 servers and PCs. Apple's Mac OS X, a hybrid kernel-based BSD variant
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derived from NeXT STEP, Mach, and FreeBSD, has replaced Apple's earlier (non-Unix)
Mac OS.
UNIX interoperability was sought by establishing the POSIX standard. The POSIX
standard can be applied to any operating system, although it was originally created for
various UNIX variants.
Mac OS X
Mac OS X "Snow Leopard"
Mac OS X is a line of partially proprietary, graphical operating systems developed,
marketed, and sold by Apple Inc., the latest of which is pre-loaded on all currently
shipping Macintosh computers. Mac OS X is the successor to the original Mac OS, which
had been Apple's primary operating system since 1984. Unlike its predecessor, Mac OS
X is a UNIX operating system built on technology that had been developed at NeXT
through the second half of the 1980s and up until Apple purchased the company in early
1997.
The operating system was first released in 1999 as Mac OS X Server 1.0, with a desktoporiented
version (Mac OS X v10.0) following in March 2001. Since then, six more
distinct "client" and "server" editions of Mac OS X have been released, the most recent
being Mac OS X v10.6, which was first made available on August 28, 2009. Releases of
Mac OS X are named after big cats; the current version of Mac OS X is nicknamed
"Snow Leopard".
The server edition, Mac OS X Server, is architecturally identical to its desktop
counterpart but usually runs on Apple's line of Macintosh server hardware. Mac OS X
Server includes work group management and administration software tools that provide
simplified access to key network services, including a mail transfer agent, a Samba
server, an LDAP server, a domain name server, and others.
Plan 9
Ken Thompson, Dennis Ritchie and Douglas McIlroy at Bell Labs designed and
developed the C programming language to build the operating system Unix.
Programmers at Bell Labs went on to develop Plan 9 and Inferno, which were engineered
for modern distributed environments. Plan 9 was designed from the start to be a
networked operating system, and had graphics built-in, unlike Unix, which added these
features to the design later. Plan 9 has yet to become as popular as Unix derivatives, but it
has an expanding community of developers. It is currently released under the Lucent
Public License. Inferno was sold to Vita Nuova Holdings and has been released under a
GPL/MIT license.
Real-time operating systems
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A real-time operating system (RTOS1) is a multitasking operating system intended for
applications with fixed deadlines (real-time computing). Such applications include some
small embedded systems, automobile engine controllers, industrial robots, spacecraft,
industrial control, and some large-scale computing systems.
An early example of a large-scale real-time operating system was Transaction Processing
Facility developed by American Airlines and IBM for the Sabre Airline Reservations
System.
Embedded systems
Embedded systems use a variety of dedicated operating systems. In some cases, the
"operating system" software is directly linked to the application to produce a monolithic
special-purpose program. In the simplest embedded systems, there is no distinction
between the OS and the application.
Embedded systems that have fixed deadlines use a real-time operating system such as
VxWorks, eCos, QNX, MontaVista Linux and RTLinux. Windows CE is a real-time
operating system that shares similar APIs to desktop Windows but shares none of desktop
Windows' codebase
Some embedded systems use operating systems such as Symbian OS, Palm OS, BSD,
and Linux, although such operating systems do not support real-time computing.
Hobby development
Operating system development or OSDev for short, as a hobby has a large cult-like
following. As such, operating systems, such as Linux, have derived from hobby operating
system projects. The design and implementation of an operating system requires skill and
determination, and the term can cover anything from a basic "Hello World" boot loader to
a fully featured kernel. One classical example of this is the Minix Operating System—an
OS that was designed by A.S. Tanenbaum as a teaching tool but was heavily used by
hobbyists before Linux eclipsed it in popularity.
Other
Older operating systems which are still used in niche markets include OS/2 from IBM
and Microsoft; Mac OS, the non-Unix precursor to Apple's Mac OS X; BeOS; XTS-300.
Some, most notably AmigaOS 4 and RISC OS, continue to be developed as minority
platforms for enthusiast communities and specialist applications. OpenVMS formerly
from DEC is still under active development by Hewlett-Packard. There were a number of
operating systems for 8 bit computers - Apple's DOS (Disk Operating System) 3.2 & 3.3
for Apple II, Pro DOS, UCSD, CP/M - available for various 8 and 16 bit environments,
FutureOS for the Amstrad CPC6128 and 6128Plus.
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Research and development of new operating systems continues. GNU Hurd is designed
to be backwards compatible with UNIX, but with enhanced functionality and a
microkernel architecture. Singularity is a project at Microsoft Research to develop an
operating system with better memory protection based on the .Net managed code model.
Systems development follows the same model used by other Software development,
which involves maintainers, version control "trees”, forks, "patches", and specifications.
From the AT&T-Berkeley lawsuit the new unencumbered systems were based on
4.4BSD which forked as FreeBSD and NetBSD efforts to replace missing code after the
UNIX wars. Recent forks include DragonFly BSD and Darwin from BSD Unix
Diversity of operating systems and protability
Application software is generally written for use on a specific operating system, and
sometimes even for specific hardware. When porting the application to run on another
OS, the functionality required by that application may be implemented differently by that
OS (the names of functions, meaning of arguments, etc.) requiring the application to be
adapted.
This cost in supporting operating systems diversity can be avoided by instead writing
applications against software platforms like Java, Qt or for web browsers. These
abstractions have already borne the cost of adaptation to specific operating systems and
their system libraries.
Another approach is for operating system vendors to adopt standards. For example,
POSIX and OS abstraction layers provide commonalities that reduce porting costs.
Application Software
Application software is a computer program that functions and is operated by means of a
computer, with the purpose of supporting or improving the software user's work. In other
words, it is the subclass of computer software that employs the capabilities of a computer
directly and thoroughly to a task that the user wishes to perform. This should be
contrasted with system software (infrastructure) or middleware (computer services/
processes integrators), which is involved in integrating a computer's various capabilities,
but typically does not directly apply them in the performance of tasks that benefit the
user. In this context the term application refers to both the application software and its
implementation
120
Microsoft windows Operating System Requirements
Windows 98
CPU Required : 486 DX66MHz and Faster
Ram : 16 MB and 32 MB
Hard Disk : 335 MB Space
Compact Disk (CD, DVD) : Up to 12X Speed
Floppy : On Boot Time
Display : 16 bit and 24 bit (VGA)
Pointer Device : Key Board, Mouse
Serial Key : HJGWK-GBD78-C7Q8D-4BKY9-P4RR6
Windows ME
CPU Required : 150 MHz or higher
Ram : 32 MB of RAM
Hard Disk : 420 MB (Depending on configuration selected)
Compact Disk (CD, DVD) : Up to 12X Speed
Floppy : On Boot Time
Display : 16 bit and 24 bit (VGA)
Pointer Device : Key Board, Mouse
Serial Key : 11111-11111-11111-11111-11111
Windows NT (4.0 Workstation)
CPU Required : Pentium 1
Ram : 16 MB of Ram
Hard Disk : Up to 110 MB
Compact Disk (CD, DVD) : Up to 12X Speed
Floppy : Not So Required
Display : VGA (800x600)
Pointer Device : Key Board, Mouse
Serial key : 145-111
121
Windows 2000 Professional
CPU Required : 133 MHz
Ram : 64 MB 0f Ram
Hard Disk : 650 MB Space
Compact Disk (CD, DVD) : Up to 12X Speed
Floppy : Not So Required
Display : SVGA (1024x768)
Pointer Device : Key Board, Mouse
Serial Key : RBDC8-VTRC8-D7972-J97JY-PRVMG
Windows XP Professional
CPU Required : 233 MHz
Ram : Up to 64 MB
Hard Disk : 1.5 GB (1500MB)
Compact Disk (CD, DVD) : Up to 12X Speed
Floppy : Not So Required
Display : SVGA (1024x768)
Pointer Device : Key Board, Mouse
Serial key : YVGKQ-B7QYX-WWPBR-M7T2R-PB8BM
: 72HHJ-8YR4B-2XT62-TJGMV-JBP68
Windows Server 2003 Standard Edition
CPU Required : 133 MHz
Ram : 128 of Ram
Hard Disk : 1.5 GB (1500MB)
Compact Disk (CD, DVD) : Up to 12X Speed
Floppy : Not So Required
Display : SVGA (1024x768)
Pointer Device : Key Board, Mouse
Serial Key : JB88F-WT2Q3-DPXTT-Y8GHG-7YYQY
122
Windows Vista, Business
CPU Required : Up to 1 GHz
Ram : 512 MB of Ram
Hard Disk : 20 GB
Compact Disk (CD, DVD) : DVD Rom
Floppy : Not So Required
Display : SVGA (1024x768) With 32 MB of Memory
Pointer Device : Key Board, Mouse
Serial Key : YFKBB-PQJJV-G996G-VWGXY -2V3X8
Windows 7, Business
CPU Required : Up to 1 GHz
Ram : 512 MB of Ram
Hard Disk : 20 GB
Compact Disk (CD, DVD) : DVD Rom
Floppy : Not So Required
Display : SVGA (1024x768) With 32 MB of Memory
Pointer Device : Key Board, Mouse
Serial Key : Not Required
Server 2008, Standard Edition
CPU Required : Up to 1.4 GHz
Ram : 1 GB of Ram
Hard Disk : 20 GB
Compact Disk (CD, DVD) : DVD Rom
Floppy : Not So Required
Display : SVGA (1024x768) With 32 MB of Memory
Pointer Device : Key Board, Mouse
Serial Key : Not Required
123
Operating Software Installation
Windwos98, Windows ME, Windows2000 Prof. Windows XP Prof, Windows
Server2003, Windows Vista, Windwos7, Windows Server2008, Red Hat Apple Inc.
Hewlett Packard Intel Corporationand Other……….
Dual Booting of Operating Software
Windwos98 :Windows2000 Prof, Windows XP Prof Windows
Server 2003
Windows ME : Windows2000 Prof, Windows XP Prof Windows
Server 2003
Windows NT (4.0) :Windows2000 Prof, Windows XP Prof Windows
Server 2003, Windows Vista, Windwos7, Windows
Server2008, Red Hat and Other
Windows2000 Prof. : Windows2000 Prof, Windows XP Prof Windows
Server 2003, Windows Vista, Windwos7, Windows
Server2008, Red Hat and Other
Windows XP Prof : Windows2000 Prof, Windows XP Prof Windows
Server 2003, Windows Vista, Windwos7, Windows
Server2008, Red Hat and Other
Windows Server 2003 :Windows2000 Prof, Windows XP Prof Windows
Server 2003, Windows Vista, Windwos7, Windows
Server2008, Red Hat and Other
Windows Vista : Windows Vista, Windwos7, Windows Server2008,
Red Hat and Other
Windwos7 : Windows Vista, Windwos7, Windows Server2008,
Red Hat and Other
Windows Server2008 : Windows Vista, Windwos7, Windows Server2008,
Red Hat and Other
Red Hat and Other : Red Hat
124
What can be Upgrade?
Windwos98 : Windows NT (4.0), Windows2000 Prof, Windows
XP Prof
Windows ME :Windows NT (4.0), Windows2000 Prof, Windows
XP Prof
Windows 2000 Prof. : Windows2000 Prof, Windows XP Prof
Windows NT Work (4.0) : Windows2000 Prof, Windows XP Prof
Windows XP Prof : Windows XP Prof
Windows Server 2003 : Windows Server 2003
Windows Vista : Windows Vista, Windwos7
Windwos7 :Windwos7
Windows Server2008 : Windows Server2008
Red Hat : Red Hat
125
M/S and Red Hat Operating System Version List
Red Hat Linux versions
The various Red Hat Linux versions have little different Errata Support Policies
Red Hat Linux 6.2E, 2000-03-27
Red Hat Enterprise Linux 2.1, 26 March 2002
Red Hat Enterprise Linux 2.1 May 2003
Red Hat Enterprise Linux 3, 2003-10-22. (Uses Linux 2.4.21)
Update 1, 16 January 2004
Update 2, 18 May 2004
Update 3, 3 September 2004
Update 4, 21 December 2004
Update 5, 20 May 2005
Update 6, 28 September 2005
Update 7, 15 March 2006
Update 8, 20 July 2006
Update 9, 15 June 2007
Red Hat Enterprise Linux 4, 2005-02-15. (Uses Linux 2.6.9)
4.1, also known as Update 1, 9 June 2005
4.2, also known as Update 2, 5 October 2005
4.3, also known as Update 3, 7 March 2006
4.4, also known as Update 4, 11 August 2006
4.5, also known as Update 5, 1 May 2007
4.6, also known as Update 6, 15 November 2007
4.7, also known as Update 7, 24 July 2008
4.8, also known as Update 8, 18 May 2009
Red Hat Enterprise Linux 5, 2007-03-14. (Uses Linux 2.6.18)
5.1 (also known as Update 1), 2007-11-07
5.2 (also known as Update 2), 2008-05-21
5.3 (also known as Update 3), 2009-01-19
5.4 (also known as Update 4), 2009-09-02
126
Microsoft
XENIX (licensed version of UNIX; licensed to SCO in 1987)
MSX-DOS (developed by MS Japan for the MSX 8-bit computer)
MS-DOS (developed jointly with IBM, versions 1.0–6.22)
Windows CE (OS for handhelds, embedded devices, and real-time applications that is
similar to other versions of Windows)
Windows CE 3.0
Windows Mobile (based on Windows CE, but for a smaller form factor)
Windows CE 5.0
Windows CE 6.0
Windows Mobile 5.0
Windows Mobile 6.0
Windows Mobile 6.1
Windows Mobile 6.5
DOS-based Windows
Windows 1.0 (Windows 1)
Windows 2.0 (Windows 2)
Windows 3.0
Windows 3.1x (Windows 3.1)
Windows 3.2 (Chinese-only release)
Windows 9x (Windows 4 Series) family
Windows 95 (Windows 4) (codename: Chicago)
Windows 98 (Windows 4.1) (codename: Memphis)
Windows Millennium Edition (Windows Me - Windows 4.9)
OS/2 (developed jointly with IBM)
Windows NT
Windows NT 3.1 (OS/2 3.0 - Windows 3.1)
Windows NT 3.5 (Windows 3.5)
Windows NT 3.51 (Windows 3.51)
Windows NT 4.0 (Windows 4)
Windows 2000 (Windows NT 5.0 - Windows 5)
Windows XP (Windows NT 5.1 - Windows 5.1) (codename: Whistler)
Windows Server 2003 (Windows NT 5.2 - Windows 5.2) (codename: Whistler Server)
Windows Fundamentals for Legacy PCs
Windows Vista (Windows NT 6.0 - Windows 6) (codename: Longhorn)
Windows Home Server
Windows Server 2008 (Windows NT 6.0 - Windows 6) (codename: Longhorn Server)
Windows 7 (previously codenamed Blackcomb, then Vienna)
Windows Preinstallation Environment (WinPE)
127
What are file systems?
As I wrote in module 4a, drives are storage media, which can hold a file system. When a
disk is formatted in a drive, it becomes organized and prepared to receive data. When we
format a disk, it receives a file system. Formatting can be compared to starting a library.
You must install the book shelves and the catalogue system before any books are put in
place. Once the library is ready, bring on the books! Similarly with a disk. When we
format it; we "burn in" a file system to make it ready to receive data (files). We can
format with any one of several different file systems
FAT (File Allocation Table), the original, old 16 bit DOS system is probably used in
90% of all PC’s. It is also called FAT16
FAT32 a new addition to FAT, which Microsoft introduced with Windows 95 B – The
December -96 versions (OSR2)?
HPFS (High Performance File System) from OS/2. It is an advanced 32 bit file system,
which in all respects is far superior to FAT, except for possible usage. It can only be used
with OS/2.
NTFS from Windows NT. A 32 bit file system like HPFS, but not compatible with it.
NTFS can, unfortunately, only be used in Windows NT. If it was available for use in
Windows 95, it would be far to preferable to FAT and FAT32.
NetWare is a server operating system from Novell. It has its own 32 bit file system.
For that reason, the Novell server, contrary to NT or OS/2 servers, cannot be used as a
work station. The file system is much faster than FAT, but it works only with Novell
servers (typically file servers).
UNIX servers have their own filing system. Here the use of upper/lower case in file
naming is significant. Read in the following pages about the concepts of these file
systems...
128
Chapter - 9
Windows shortcut Key
Windows shortcut key
Windows system key combinations
• F1: Help
• CTRL+ESC: Open Start menu
• ALT+TAB: Switch between open programs
• ALT+F4: Quit program
• SHIFT+DELETE: Delete item permanently
Windows program key combinations
• CTRL+C: Copy
•
CTRL+X: Cut
• CTRL+V: Paste
• CTRL+Z: Undo
•
CTRL+B: Bold
• CTRL+U: Underline
• CTRL+I: Italic
Mouse click/keyboard modifier combinations for shell objects
• SHIFT+right click: Displays a shortcut menu containing alternative
commands
• SHIFT+double click: Runs the alternate default command (the second
item on the menu)
• ALT+double click: Displays properties
• SHIFT+DELETE: Deletes an item immediately without placing it in the
Recycle Bin
General keyboard-only commands
• F1: Starts Windows Help
• F10: Activates menu bar options
• SHIFT+F10 Opens a shortcut menu for the selected item (this is the same
129
as right-clicking an object
• CTRL+ESC: Opens the Start menu (use the ARROW keys to select an
item)
• CTRL+ESC or ESC: Selects the Start button (press TAB to select the
taskbar, or press SHIFT+F10 for a context menu)
• ALT+DOWN ARROW: Opens a drop-down list box
• ALT+TAB: Switch to another running program (hold down the ALT key
and then press the TAB key to view the task-switching window)
• SHIFT: Press and hold down the SHIFT key while you insert a CD-ROM
to bypass the automatic-run feature
• ALT+SPACE: Displays the main window's System menu (from the
System menu, you can restore, move, resize, minimize, maximize, or
close the window)
• ALT+- (ALT+hyphen): Displays the Multiple Document Interface (MDI)
child window's System menu (from the MDI child window's System
menu, you can restore, move, resize, minimize, maximize, or close the
child window)
• CTRL+TAB: Switch to the next child window of a Multiple Document
Interface (MDI) program
• ALT+underlined letter in menu: Opens the menu
• ALT+F4: Closes the current window
• CTRL+F4: Closes the current Multiple Document Interface (MDI)
window
• ALT+F6: Switch between multiple windows in the same program (for
example, when the Notepad Find dialog box is displayed, ALT+F6
switches between the Find dialog box and the main Notepad window)
Shell objects and general folder/Windows Explorer shortcuts
For a selected object:
• F2: Rename object
• F3: Find all files
• CTRL+X: Cut
• CTRL+C: Copy
• CTRL+V: Paste
• SHIFT+DELETE: Delete selection immediately, without moving the item
to the Recycle Bin
• ALT+ENTER: Open the properties for the selected object
General folder/shortcut control
• F4: Selects the Go To A Different Folder box and moves down the entries
in the box (if the toolbar is active in Windows Explorer)
• F5: Refreshes the current window.
• F6: Moves among panes in Windows Explorer
130
• CTRL+G: Opens the Go To Folder tool (in Windows 95 Windows
Explorer only)
• CTRL+Z: Undo the last command
• CTRL+A: Select all the items in the current window
• BACKSPACE: Switch to the parent folder
• SHIFT+click+Close button: For folders, close the current folder plus all
parent folders
Windows Explorer tree control
• Numeric Keypad *: Expands everything under the current selection
• Numeric Keypad +: Expands the current selection
• Numeric Keypad -: Collapses the current selection.
• RIGHT ARROW: Expands the current selection if it is not expanded,
otherwise goes to the first child
• LEFT ARROW: Collapses the current selection if it is expanded,
otherwise goes to the parent
Properties control
• CTRL+TAB/CTRL+SHIFT+TAB: Move through the property tabs
Accessibility shortcuts
• Press SHIFT five times: Toggles StickyKeys on and off
• Press down and hold the right SHIFT key for eight seconds: Toggles
FilterKeys on and off
• Press down and hold the NUM LOCK key for five seconds: Toggles
ToggleKeys on and off
• Left ALT+left SHIFT+NUM LOCK: Toggles MouseKeys on and off
• Left ALT+left SHIFT+PRINT SCREEN: Toggles high contrast on and
off
Microsoft Natural Keyboard keys
• Windows Logo: Start menu
• Windows Logo+R: Run dialog box
• Windows Logo+M: Minimize all
• SHIFT+Windows Logo+M: Undo minimize all
• Windows Logo+F1: Help
• Windows Logo+E: Windows Explorer
• Windows Logo+F: Find files or folders
• Windows Logo+D: Minimizes all open windows and displays the desktop
• CTRL+Windows Logo+F: Find computer
• CTRL+Windows Logo+TAB: Moves focus from Start, to the Quick
Launch toolbar, to the system tray (use RIGHT ARROW or LEFT
131
ARROW to move focus to items on the Quick Launch toolbar and the
system tray)cccccc
• Windows Logo+TAB: Cycle through taskbar buttons
• Windows Logo+Break: System Properties dialog box
• Application key: Displays a shortcut menu for the selected item
Microsoft Natural Keyboard with IntelliType software installed
• Windows Logo+L: Log off Windows
• Windows Logo+P: Starts Print Manager
• Windows Logo+C: Opens Control Panel
• Windows Logo+V: Starts Clipboard
• Windows Logo+K: Opens Keyboard Properties dialog box
• Windows Logo+I: Opens Mouse Properties dialog box
• Windows Logo+A: Starts Accessibility Options (if installed)
• Windows Logo+SPACEBAR: Displays the list of Microsoft IntelliType
shortcut keys
• Windows Logo+S: Toggles CAPS LOCK on and off
Dialog box keyboard commands
• TAB: Move to the next control in the dialog box
• SHIFT+TAB: Move to the previous control in the dialog box
• SPACEBAR: If the current control is a button, this clicks the button. If
the current control is a check box, this toggles the check box. If the
current control is an option, this selects the option.
• ENTER: Equivalent to clicking the selected button (the button with the
outline)
• ESC: Equivalent to clicking the Cancel button
• ALT+underlined letter in dialog box item: Move to the corresponding
item
132
XP Run Commands
Here is a list of commands you can execute from the Run command prompt in XP:
Accessibility Controls
access.cpl
Add Hardware Wizard
hdwwiz.cpl
Add/Remove Programs
appwiz.cpl
Administrative Tools
certmgr.msc
Character Map
charmap
Check Disk Utility
chkdsk
Clipboard Viewer
clipbrd
Command Prompt
cmd
Component Services
dcomcnfg
Computer Management
compmgmt.msc
Date and Time Properties
timedate.cpl
DDE Shares
ddeshare
Device Manager
devmgmt.msc
Direct X Control Panel (If Installed)
directx.cpl
Direct X Troubleshooter
dxdiag
Disk Cleanup Utility
cleanmgr
Disk Defragment
dfrg.msc
Disk Management
diskmgmt.msc
Disk Partition Manager
diskpart
Display Properties
control desktop
Display Properties
desk.cpl
Display Properties (w/Appearance Tab Preselected)
133
control color
Dr. Watson System Troubleshooting Utility
drwtsn32
Driver Verifier Utility
verifier
Event Viewer
eventvwr.msc
File Signature Verification Tool
sigverif
Findfast
findfast.cpl
Folders Properties
control folders
Fonts
control fonts
Fonts Folder
fonts
Free Cell Card Game
freecell
Game Controllers
joy.cpl
Group Policy Editor (XP Prof)
gpedit.msc
Hearts Card Game
mshearts
Iexpress Wizard
iexpress
Indexing Service
ciadv.msc
Internet Properties
inetcpl.cpl
IP Configuration (Display Connection Configuration)
ipconfig /all
IP Configuration (Display DNS Cache Contents)
ipconfig /displaydns
IP Configuration (Delete DNS Cache Contents)
ipconfig /flushdns
IP Configuration (Release All Connections)
ipconfig /release
IP Configuration (Renew All Connections)
ipconfig /renew
IP Configuration (Refreshes DHCP & Re-Registers DNS)
ipconfig /registerdns
IP Configuration (Display DHCP Class ID)
ipconfig /showclassid
IP Configuration (Modifies DHCP Class ID)
134
ipconfig /setclassid
Java Control Panel (If Installed)
javaws
Keyboard Properties
control keyboard
Local Security Settings
secpol.msc
Local Users and Groups
lusrmgr.msc
Logs You Out Of Windows
logoff
Microsoft Chat
winchat
Minesweeper Game
winmine
Mouse Properties
control mouse
Mouse Properties
main.cpl
Netstat
netstat
Network Connections
control netconnections
Network Connections
ncpa.cpl
Network Setup Wizard
netsetup.cpl
Notepad
notepad
Nview Desktop Manager (If Installed)
nvtuicpl.cpl
Object Packager
packager
ODBC Data Source Administrator
odbccp32.cpl
On Screen Keyboard
osk
Opens AC3 Filter (If Installed)
ac3filter.cpl
Password Properties
password.cpl
Performance Monitor
perfmon.msc
Performance Monitor
perfmon
Phone and Modem Options
135
telephon.cpl
Power Configuration
powercfg.cpl
Printers and Faxes
control printers
Printers Folder
printers
Private Character Editor
eudcedit
Quicktime (If Installed)
QuickTime.cpl
Regional Settings
intl.cpl
Registry Editor
regedit
Remote Desktop
mstsc
Removable Storage
ntmsmgr.msc
Removable Storage Operator Requests
ntmsoprq.msc
Resultant Set of Policy (XP Prof)
rsop.msc
Scanners and Cameras
sticpl.cpl
Scheduled Tasks
control schedtasks
Security Center
wscui.cpl
Services
services.msc
Shared Folders
fsmgmt.msc
Shuts Down Windows
shutdown
Sounds and Audio
mmsys.cpl
Spider Solitare Card Game
spider
SQL Client Configuration
cliconfg
System Configuration Editor
sysedit
System Configuration Utility
msconfig
System File Checker Utility (Scan Immediately)
136
sfc /scannow
System File Checker Utility (Scan Once At Next Boot)
sfc /scanonce
System File Checker Utility (Scan On Every Boot)
sfc /scanboot
System File Checker Utility (Return to Default Setting)
sfc /revert
System File Checker Utility (Purge File Cache)
sfc /purgecache
System File Checker Utility (Set Cache Size to size x)
sfc /cachesize=x
System Properties
sysdm.cpl
Task Manager
taskmgr
Telnet Client
telnet
Traceroute
tracert <hostname or IP>
User Account Management
nusrmgr.cpl
Utility Manager
utilman
Windows Firewall
firewall.cpl
Windows Magnifier
magnify
Windows Management Infrastructure
wmimgmt.msc
Windows System Security Tool
syskey
Windows Update Launches
wupdmgr
Windows XP Tour Wizard
tourstart
Wordpad
Write
Calc - Calculator
Cfgwiz32 - ISDN Configuration Wizard
Charmap - Character Map
Chkdisk - Repair damaged files
Cleanmgr - Cleans up hard drives
Clipbrd - Windows Clipboard viewer
Cmd - Opens a new Command Window (cmd.exe)
Control - Displays Control Panel
Dcomcnfg - DCOM user security
137
Debug - Assembly language programming tool
Defrag - Defragmentation tool
Drwatson - Records programs crash & snapshots
Dxdiag - DirectX Diagnostic Utility
Explorer - Windows Explorer
Fontview - Graphical font viewer
Ftp - ftp.exe program
Hostname - Returns Computer's name
Ipconfig - Displays IP configuration for all network adapters
Jview - Microsoft Command-line Loader for Java classes
MMC - Microsoft Management Console
Msconfig - Configuration to edit startup files
Msinfo32 - Microsoft System Information Utility
Nbtstat - Displays stats and current connections using NetBios over TCP/IP
Netstat - Displays all active network connections
Nslookup- Returns your local DNS server
Ping - Sends data to a specified host/IP
Regedit - egistry Editor
Regsvr32 - egister/de-register DLL/OCX/ActiveX
Regwiz - Reistration wizard
Sfc /scannow - Sytem File Checker
Sndrec32 - Sound Recorder
Sndvol32 - Volume control for soundcard
Sysedit - Edit system startup files (config.sys, autoexec.bat, win.ini, etc.)
Taskmgr - Task manager
Telnet - Telnet program
Tracert - Traces and displays all paths required to reach an internet host
Winipcfg - Displays IP configuration
Management Consoles
certmgr.msc - Certificate Manager
ciadv.msc - Indexing Service
compmgmt.msc - Computer management
devmgmt.msc - Device Manager
dfrg.msc - Defragment
diskmgmt.msc - Disk Management
fsmgmt.msc - Folder Sharing Management
eventvwr.msc - Event Viewer
gpedit.msc - Group Policy -XP Pro only
iis.msc - Internet Information Services
lusrmgr.msc - Local Users and Groups
mscorcfg.msc - Net configurations
ntmsmgr.msc - Removable Storage
perfmon.msc - Performance Manager
secpol.msc - Local Security Policy
services.msc - System Services
wmimgmt.msc - Windows Management
138
access.cpl - Accessibility Options
hdwwiz.cpl - Add New Hardware Wizard
appwiz.cpl - dd/Remove Programs
timedate.cpl - Date and Time Properties
desk.cpl - Display Properties
inetcpl.cpl - Internet Properties
joy.cpl - Joystick Properties
main.cpl keboard - Keyboard Properties
main.cpl - Mouse Properties
ncpa.cpl - Network Connections
ncpl.cpl - Network Properties
telephon.cpl - Phone and Modem options
powercfg.cpl - Power Management
intl.cpl - Regional settings
mmsys.cpl sounds - Sound Properties
mmsys.cpl - Sounds and Audio Device Properties
sysdm.cpl - System Properties
nusrmgr.cpl - User settings
firewall.cpl - Firewall Settings (sp2)
wscui.cpl - Security Center (sp2)
WRITE -WordPad.
WSCRIPT -Script Hosting Settings.
WUPDMGR -Windows Update Manager.
WMIMGMT.MSC -Windows Management Infrastructure.
WINVER -Tells About Windows License And a Little System Information.
WINMSD -System Information.
MSINFO32 -Detailed System Information.
WINMINE -Mine Game.
WINHLP32 -Opens Help File Of Specified Program.
WINCHAT -Chat With Other Computer On Internet Or LAN. WIAACMGR -Camera
And Scanner Utility.
VERIFIER -Driver Verification Utility (Not turned off automatically).
VERIFIER /RESET -Ends Driver Verification.
UTILMAN -Utility Manager.
USERINIT -Opens Folder Tab Under ‘My Document’.
TSSHUTDN -System Shut Down (in 60 sec.) Utility.
TSDISCON -Exits (Not Logs Off) Current User.
TOURSTART -Xp Tour.
TLNTSVR -Starts Telnet Server.
TCMSETUP -Telephone Client Help.
TASKMGR -Task Manager.
SYSKEY -XP Account Database Additional Encryption. SSMYPICS.SCR -Screen Saver
With ‘My Picture’ Folder.
SPIDER -Spider Solitaire Game.
SOL -Solitaire Game.
SNDVOL32 -Volume Control.
139
SNDREC32 -Sound Recording Utility.
SIGVERIF -File Signature Verification.
SHRPUBW -Shared Folder Creation Wizard.
SERVICES.MSC -Services’ Utility.
SECPOL.MSC -Local Security Setting.
SECEDIT -Security Configuration Management Help File. SC -CMD Program To
Communicate With NT Service Controller.
RUNDLL32 -Start Specified DLL.
NETSHARE -Sharing Session.
RSOP.MSC -Resultant Set Of Policy.
REGEDIT -Registry Editor.
RASPHONE -Network Connection.
PERFMON -Enhanced Performance Monitor.
PACKAGER -Object Packager.
OSK -On Screen Keyboard.
ODBCAD32 -ODBC Data Source Management.
NTMSOPRQ.MSC -Removal Storage Operator Request Management. NTMSMGR.MSC
-Removal Storage Management.
NTBACKUP -Backup Utility.
NOTEPAD -Notepad.
NSLOOKUP -Default Server Information.
NETSETUP -Network Setup Wizard.
MSTSC -Remote Desktop Connection.
MSPAINT -Microsoft Paint.
MSHEARTS -Hearts Game.
MPLAY32 -Media Player And Editor.
MOBSYNC -Synchronizing Tool.
MMC -Microsoft Management Console.
MAGNIFY -Magnifier.
LUSRMGR.MSC -Local User And Group Management.
LOGOFF -Log Off.
LABEL X: -Create label For X Drive.
IEXPRESS -Iexpress Wizard.
GPEDIT.MSC -Group Policy Editor.
FTP -CMD FTP Client.
FSQUIRT -Bluetooth File Transfer Wizard.
FSMGMT -Shared Folder Management.
FREECELL -FreeCell Game.
EVENTVMR -Event Viewer.
EUDCEDIT -Private Character Editor.
DXDIAG -DirectX Diagnosis Tool.
DVDPLAY -Open WMP For DVD Playback.
DRWTSN32 -Dr. Watson.
DISKMGMT.MSC -Disk Management Service.
DFRG.MSC -Disk Defragmenter.
DEVMGMT.MSC -Device Management.
140
DCOMCNFG -Component Services.
CONTROL -Control Panel.
COMPMGMT.MSC -Component Management.
COMP -File Comparison.
CMD -Command Prompt.
CLIPBRD -Clipboard Viewer.
CLICONFG -SQL Server Client Network Utility.
CLEANMGR -Disk Cleaner.
CLEANMGR /SAGESET:99 -Automatic Disk Cleanup Utility.
CIADV.MSC -Indexing Service.
CHKDSK X: -Disk Checking Utility For Drive X.
CHARMAP -Character Map.
CERTMGR.MSC -File Certificate Manger.
CALC -Calculator.
ACCWIZ -Accessibility Wizard.
ACCESS.CPL -Accessibility Option.
APPWIZ.CPL -Add/Remove Program Utility.
DESK.CPL -Desktop Property.
FIREWALL.CPL -Firewall Setting.
HDWWIZ.CPL -Add Hardware wizard.
INETCPL.CPL -Internet Property.
INTL.CPL -Region And Language Setting.
JOY.CPL -Game Controller Setup.
MAIN.CPL -Mouse Property.
MMSYS.CPL -Sound Property.
NCPA.CPL -View Network Connection.
NETSETUP.CPL -Network Setup Wizard.
NUSRMGR.CPL -Account Management.
ODBCCP32.CPL -ODBC Data Source Administrator.
JPICPL32.CPL -JAVA Plug-in Control Panel.
POWERCFG.CPL -Power Option.
SYSDM.CPL -System Property.
TELEPHON.CPL -Phone And Modem Property.
TIMEDATE.CPL -Date And Time Property.
WSCUI.CPL -Windows Security Center.
WUACPL.CPL -Automatic Update Setting.
Windows Environment Commands
%ALLUSERSPROFILE% - Open the All User's Profile
%HomeDrive% - Opens your home drive e.g. C:\
%UserProfile% - Opens you User's Profile
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%temp% Opens - temporary file Folder
%systemroot% - Opens Windows folder
Wupdmgr - Takes you to Microsoft Windows Update
Dsa.msc – a.d open
RECENT – OPEN RECENT ITEM
\documents and settings
\program files
\windows
\wmpub
Msmgs =window messenger
Dnsmgmt.msc
Dhcpmgmt.msc
Systeminfo
Rrasmgmgt.msc
Dcpromo /force removal
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Chapter-10
Some Sort Form
Accelerated Graphics Port (AGP) A bus developed to meet the need for increased
graphics performance.
Active partition the partition from which an operating system boots. Adapter card a
daughter card that extends the capabilities of the motherboard.
Advanced Configuration and Power Interface (ACPI) a standard that defines common
interfaces for hardware recognition and configuration, and more importantly, power
management.
Answer file in an unattended installation, this file contains all of the correct parameters
(time zone, regional settings, administrator user name, and so on), needed for installation.
AppleTalk A proprietary network protocol for Macintosh computers.
AT system connector the power-supply connector pair for the AT motherboard often
marked P8 and P9 that was used in the original IBM PC but is now associated by name
with the PC/AT.
Attended installation an installation where a user is required to provide answers to
options during the installation process.
ATX motherboard a smaller successor to the AT motherboard that uses space more
wisely and places related components closer together.
ATX system connector the single, larger power-supply connector that powers the ATX
motherboard.
Authentication A process that proves that a user or system is actually who they say they
are.
Automated System Recovery (ASR) ASR first creates a backup of your system partition
And then creates a recovery disk. Using these two components, you can recover from a
system crash and restore the system to a functional state.
Autorun When a compact disc automatically begins its program when it’s inserted into
the computer.
Baby AT A form factor that denotes AT compatibility but in a smaller size. Backside
bus a set of signal pathways between the CPU and Level 2 cache memory. Backup A
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copy of files stored in a location other than where they originally came from. Backlight
A small fluorescent lamp placed behind, above, or to the side of an LCD display.
Berg connectors the official name for the smaller peripheral power-supply connectors
that most often attach to floppy disk drives.
Bidirectional A satellite connection wherein the satellite is used for both uploads and
downloads.
Blue screen of death (BSOD) the blue-screen error condition that occurs when Windows
2000/XP fails to boot properly or quits unexpectedly.
Bluetooth A popular standard for wireless communication.
Bluetooth Special Interest Group (SIG) The consortium of companies that developed the
Bluetooth technology.
BNC A type of connector used to attach stations to a Thinnet network.
Bonding Combining two bearer channels into one 128Kbps data connection to
maximize throughput.
Boot logging Logs all boot information to a file called NTBTLOG.TXT. You can then
check the log for assistance in diagnosing system startup problems.
Boot ROM A piece of hardware (often built into a network card) that is capable of
downloading a small file that contains enough information to boot the computer and
attach it to the network.
Broadband The general designation for higher-speed Internet connections. Broadcast
To send a signal to all entities that can listen to it. In networking, it refers to
Sending a signal to all entities connected to that network.
Bubble-jet printer a type of sprayed-ink printer. It uses an electric signal that energizes a
heating element, causing ink to vaporize and be pushed out of the pinhole and onto the
paper.
Carriage belt the printer belt placed around two small wheels or pulleys and attached to
the print head carriage. The carriage belt is driven by the carriage motor and moves the
print head back and forth across the page during printing.
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Carriage motor a stepper motor used to move the print head back and forth on a dotmatrix
printer.
Carriage stepper motor the printer motor that makes the print head carriage move.
Case The external container for the system.
Case frame the metal reinforcing structure inside the laptop that provides rigidity and
strength and that most components mount to.
Cell A cellular phone network. Central processing unit (CPU) the microprocessor chips
that gives a computer its fundamental characteristics.
Centralized processing a network processing scheme in which all “intelligence” is found
in one computer and all other computers send requests to the central computer to be
processed. Mainframe networks use centralized processing.
Certificates A common form of authentication.
Charge coupled device (CCD) array a matrix of photosensitive capacitors arranged so
that one capacitor charges its neighbor, resulting in a representative sample for a row of
capacitors. CCD arrays are used as photoreceptors in scanners and digital photographic
equipment.
Charging corona the wire or roller that is used to put a uniform charge on the EP drum
Inside a toner cartridge.
Charging step the step in EP printing at which a special wire in the toner cartridge gets a
High voltage from the HVPS. It uses this high voltage to apply a strong, uniform negative
charge (around -600VDC) to the surface of the photosensitive drum.
Chipset A small group of larger chips that takes the place of a large number of earlier
chips to perform a similar function.
Clamshell designs a popular design for laptops.
Cleaning cycle a set of steps the bubble-jet printer goes through in order to purge the
print heads of any dried ink.
Cleaning step the step in the EP print process at which excess toner is scraped from the
EP drum with a rubber blade.
Client computer a computer that requests resources from a network. Client software
that allows a device to request resources from a network.
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CMOS battery the battery that maintains without external power the contents of the
special memory chip that holds the alterations made to the BIOS settings.
Coaxial cable a medium for connecting computer components that contains a center
conductor, made of copper, surrounded by a plastic jacket, with a braided shield over the
jacket.
Collision light The LED on a network device that indicates the detection of a collision.
Communication network riser (CNR) Sixty-pin slots found on some Intel motherboards
that are a replacement for AMR slots. Using CNR slots, a motherboard manufacturer can
implement a motherboard with certain integrated features and leave room for future
expansion.
Compact disc-recordable (CD-R) and compact disc-rewritable (CD-RW) drives
Compact
Disc drives with the capability to “burn” contents to specially manufactured discs.
Compact installation Also known as a minimal installation, it installs only the files
necessary to run Windows.
Compression a feature in Windows 2000 and XP that gives you the option of
compressing existing files in a particular folder. If the feature is turned on, Windows
2000 and XP automatically compress the subfolders and files. If not, only new files
created in the directory are compressed.
Computer name the name by which a computer will be known if it participates on a
Network.
Connectivity device any device that facilitates connections between network devices.
Some examples include hubs, routers, switches, and gateways.
Corona roller a type of transfer corona assembly that uses a charged roller to apply
charge to the paper.
Corona wires a type of transfer corona assembly. Also, the wire in that assembly that is
Charged by the high-voltage supply. It is narrow in diameter and located in a special
notch under the EP print cartridge.
Custom installation an installation method where the user gets to choose which
components are installed.
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Daisy-wheel printer an impact printer that uses a plastic or metal print mechanism with
a different character on the end of each spoke of the wheel. As the print mechanism
rotates to the correct letter, a small hammer strikes the character against the ribbon,
transferring the image onto the paper.
Daughterboard Any circuit board connected to the motherboard. DC adapter the
adapter which provides DC current to the laptop.
Dedicated server the server that is assigned to perform a specific application or service.
Decrementing Reorganizing files on a hard disk so they are in consecutive order.
Delay An impedance to the flow of a signal that causes the moment of transmission by
the source to be earlier than the moment of receipt by the destination.
Denial of Service (DoS) attacks that prevent access to resources by users authorized to
use those resources.
Developing roller the roller inside a toner cartridge that presents a uniform line of toner
to help apply the toner to the image written on the EP drum. Developing step the step in
the EP print process at which the image written on the EP drum by the laser is
developed—that is, it has toner stuck to it.
Device driver a software file that allows an operating system to communicate with a
hardware device. Also called a driver.
Digitally signed driver a driver that has been digitally “signed” by Microsoft with a
special value that only Windows can read. This signature tells the Windows installer that
the driver being installed has been tested for security and stability on the chosen
Windows platform and that the driver is from a reputable source.
Direct-solder method a method of connecting a peripheral port by directly soldering
individual ports to the motherboard. This method is used mostly in integrated
motherboards in non-clone machines.
Disk cache a small amount of memory that is used to hold data that is frequently
accessed from the hard disk.
Diskette One of variously sized magnetic-coated Mylar disks packaged in a square
protective cover.
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Distributed processing a computer system in which processing is performed by several
separate computers linked by a communications network. The term often refers to any
computer system supported by a network, but more properly refers to a system in which
each computer is chosen to handle a specific workload and the network supports the
system as a whole.
DIX Ethernet the original name for the Ethernet network technology. Named after the
original developer companies: Digital, Intel, and Xerox.
Docking port a port used to connect the laptop to a special laptop. Docking station and
extension of the motherboard of a laptop.
Dot-matrix printer impact printers that have a print head containing a row of pins (short,
sturdy stalks of hard wire) that are used to strike the ink ribbon to create an image.
Dot phosphor the phosphorescent chemical dots that coat the back of a CRT monitor’s
Screen. Electron beams excite these dots and cause them to glow.
Dot pitches the average measurement between two dot phosphors on a CRT screen. The
smaller the dot pitch, the better the picture quality.
Drive interfaces the connectors and related technology used to attach drives and similar
devices to adapters or the motherboard. Examples include ATA, SCSI, and ESDI.
Driver A software file that allows an operating system to communicate with a hardware
device. Also called a device driver.
Dual-boot configuration a computer that has more than one operating system installed.
During boot, the user can choose which operating system to start.
Dual Inline Memory Modules (DIMMs) Memory sticks that install in slots on
motherboards and specialty devices to act as primary memory in service of the CPU.
DIMMs are so named for the fact that the pins on each side of the module are
independent of one another. Contrast with Single Inline Memory Modules (SIMMs).
Electron gun the devices that shoot a beam of electrons at the back of a CRT screen to
illuminate the dot phosphors, thus producing an image on the front of the screen.
Electromagnetic interference (EMI) any electromagnetic radiation released by an
electronic device that disrupts the operation or performance of any other device.
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Electronic stepper motor a special electric motor in a printer that can accurately move in
Very small increments. It powers all of the paper transport rollers as well as the fuser
rollers.
Emergency repair disk (ERD) a disk that contains backup copies of portions of your
Registry. It can be used to recover the system in the event of an operating system failure.
Ethernet A network technology based on the IEEE 802.3 CSMA/CD standard. The
original Ethernet implementation specified 10MBps, baseband signaling, coaxial cable,
and CSMA/CD media access.
Ethernet port A LAN interface that follows the Ethernet standard. Ethernet ports can be
the most popular eight-pin modular connector, referred to as an RJ-45, or it can be a fiber
or coaxial interface. The Ethernet port is found on the NIC in a computer system.
Expansion cards a daughter card that expands the capabilities of a motherboard. Also
known as an adapter card.
Expansion slots on a motherboard to receive expansion cards. Expansion cards and slots
must be of the same type, PCI, Pie, or AGP, for example.
Extended Graphics Array (XGA) Introduced in 1990 by IBM, this is often thought of as
a synonym for the 1024 × 768.
Fax modem an adapter that fits into a PC expansion slot and provides many of the
capabilities of a full-sized fax machine, but at a fraction of the cost.
Feed roller the rubber roller in a laser printer that feeds the paper into the printer. Feeder
A device that feeds paper or other media into a printer.
File Allocation Table (FAT) 16 an acronym for the file on this file system used to keep
track of where files are. Many OS s have built their filesystem on the design of FAT, but
without its limitations. A FAT file system uses the 8.3 naming convention (eight letters
for the name, a period, and then a three-letter file identifier). This later became known as
FAT16 (to differentiate it from FAT32) because it used a 16-bit binary number to hold
cluster-numbering information. Because of that number, the largest FAT disk partition
that could be created was approximately 2GB.
File locking a feature of many network operating systems that “locks” a file to prevent
more than one person from updating the file at the same time.
File permissions These serve the purpose of controlling who has access and what type of
access to what files or objects they have.
Files and Settings Transfer Wizard A Windows XP utility that transfers files and
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individual application settings from an old computer to a new one.
finisher A device on a printer that performs such final functions as folding, stapling,
hole punching, sorting, or collating the documents being printed.
FireWire A trade name for IEEE 1394, FireWire is a competing standard of USB.
Firmware Software encoded on hardware. The BIOS routine and its chip is an example
of firmware.
Flatbed scanner an optical device that can be used to digitize a whole page or a large
image. Floppy disk See diskette.
Floppy drive the hardware device that reads and writes to a floppy disk.
Floppy drive interfaces the drive interface for the floppy subsystem, which consists of
34 pins and is not compatible with the various hard drive interfaces.
Floppy drive power connectors See Berg connectors.
Font the typestyle used for printing a document. The font can be loaded onto the hard
drive of the computer or the onboard memory of the printer.
Format to prepare a volume to receive files and folders by defining the file structure
formatting The process of preparing the partition to store data in a particular fashion.
Frame The Data Link layer product that includes a portion of the original user data,
upper layer headers, and the Data Link header and trailer.
Front side bus a set of signal pathways between the CPU and main memory. full AT
The original AT form factor, which was followed by the baby AT form factor. Fullduplex
communication Communications where both entities can send and receive
Simultaneously.
Full installation an installation method that installs every component, even those that
may not be required or used frequently.
Fuser A device on an EP printer that uses two rollers to heat the toner particles and melt
them to the paper. The fuser is made up of a halogen heating lamp, a Teflon-coated
aluminum fusing roller, and a rubberized pressure roller. The lamp heats the aluminum
roller. As the paper passes between the two rollers, the rubber roller presses the paper
against the heated roller. This causes the toner to melt and become a permanent image on
the paper.
Fusing step the step in the EP printing process during which the toner image on the paper
is fused to the paper using heat and pressure. The heat melts the toner, and the
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pressure helps fuse the image permanently to the paper.
Game port A DA15F interface designed for joysticks and other game controllers.
Global System for Mobile Communications (GSM) The most popular cellular standard.
It uses a variety of bands to transmit. The most popular are 900 MHz and 1800 MHz, but
400, 450, and 850 MHz are also used.
graphics mode As opposed to text mode, graphics mode displays shapes and images not
Based on text characters.
Handheld scanner a type of scanner that is small enough to be held in your hand. Used
to digitize a relatively small image or artwork, it consists of the controller, CCD, and
light source contained in a small enclosure with wheels on it.
Hardening The process of reducing or eliminating weaknesses, securing services, and
attempting to make your environment immune to attacks.
Hardware Compatibility List (HCL) A list of all the hardware that works with Windows
and which versions of Windows it works with.
Header Information attached to the beginning of a network data frame. Heat spreaders
Metal covers for memory modules that act as heat sinks. Hermaphroditic data connector
a connector that is both male and female. Hibernation A state that laptops are capable of
entering in.
High-voltage probe a tool with a very large needle, a gauge that indicates volts, and a
wire with an alligator clip used to discharge electricity from electronic devices.
Home computer In Remote Desktop, the home computer is the one you are sitting at,
and
The computer that makes the connection to the remote computer.
I/O memory Standard memory locations attributed to devices connected through
expansion buses and accessed by the I/O signal of the I/O_MEM line from the processor
to the memory controller
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Image An exact replica of an installed computer, used to install an operating system on
other computers.
Impact printers any printer that forms an image on paper by forcing a character image
against an inked ribbon. Dot-matrix, daisy-wheel, and line printers are all impact printers,
whereas laser printers are not.
Industry Standard Architecture (ISA) expansion slot an old, nearly obsolete type of
Expansion slot in a motherboard.
Infrared Data Association (IrDA) standard a personal area network (PAN) standard for
The exchange of data over short distances using infrared light.
Infrared port A serial port that uses line-of-sight to attach to another infrared port for the
Exchange of data using IrDA.
Infrared transmissions Wireless transmission between devices that use radiation in the
infrared range of the electromagnetic spectrum.
Ink cartridge a reservoir of ink and a print head, in a removable package. Inoculating
Making the computer resistant to computer viruses.
Integrated system board a motherboard with components built in, reducing the need for
a large number of expansion cards.
Interface The port or connection through which a device attaches to an external
component, such as a printer’s parallel or USB port for connection to a computer, as well
as the software that enables the port to communicate with the external component, such
as a Windows XP driver for an HP LaserJet.
Interface circuitry that converts the signals from the interface into the DataStream that
the printer or other device uses.
Interface software the operating system-specific driver that enable communication
between the computer and a peripheral.
Interlaced A video standard that scans alternate lines on the monitor with each pass,
effectively halving the nominal refresh rate. Contrast with progressive.
Internet service providers (ISP) a company that provides Internet access and e-mail
Addresses for users. Generally, ISPs are local or regional companies.
Internet work Any TCP/IP network that spans router interfaces. Anything from a small
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office with two subnets to the Internet itself can be described as an internet work.
Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX) the default
communication protocol for versions of the Novell NetWare operating system before
NetWare 5. IPX and SPX correspond loosely to IP and TCP, respectively, in the TCP/IP
protocol suite.
Keyboard/mouse port the port that the keyboard or mouse connects to. Laser printer a
generic name for a printer that uses the electro photographic (EP) print process.
Last Known Good Configuration An advanced boot option that lets you restore the
system to a prior, functional state, which will allow you to log in again.
Letter quality (LQ) a category of dot-matrix printer that can print characters that look
very close to the quality a laser printer might produce.
Liquid cooling the use of a circulating liquid, such as water, to dissipate heat.
Logical topology the topology that defines how the data flows in a network. MAC
addresses the unique physical address for each NIC.
Main motor a printer stepper motor that is used to advance the paper.
Maintenance station Provides a zero position for the an ink- or bubble-jet print head and
Keeps the print nozzles clear between print jobs.
Master computer in sysprep, the master computer is the one that is used to make an
image.
Material Safety Data Sheet (MSDS) A document that contains safety information about
a given product. Information provided includes safe handling procedures, what to do in
case of an accident, and disposal information.
MicroDIMM A 45.5mm × 30mm memory module that is over 50 percent smaller than a
SoDIMM. MicroDIMMs were designed for ultra light and portable sub notebook
computers and have 144 or 172 pins.
Minimal installation also known as a compact installation, it installs only the files
necessary to run Windows.
Mini PCI An adaptation of the Peripheral Component Interconnect (PCI) standard used
in desktop computers designed primarily for laptops.
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Modem A concatenation of modulator/demodulator. Modems allow the transmission of
a digital bit stream over an analog medium, such as a standard phone line.
Molex connector the larger peripheral power connector used on such devices as hard
drives and CD/DVD drives.
Monochrome Using a single color to display text and graphics on a screen with a
contrasting background.
Motherboard The main system board of a computer. Daughterboards interface with the
motherboard to expand its capabilities.
Multifunction printers a peripheral that is essentially a printer, copier, scanner, and fax
machine all in one.
Multiplexer A network device that combines multiple data streams into a single stream
for transmission. Multiplexers can also break out the original data streams from a single,
multiplexed stream.
Multipurpose server a server that has more than one use. For example, a multipurpose
Server can be both a file server and a print server.
Nonintegrated system board a motherboard that does not have peripheral interfaces,
Other than keyboard and mouse, permanently attached. These features must come from
expansion cards.
Northbridge A portion of a motherboard’s overall chipset that is responsible for
communications with integrated video and between the processor and memory.
Null modem serial cable a serial cable that crosses signal lines so that a modem is not
necessary to connect two computers directly.
Paper tray the tray that holds paper until it is fed into a printer.
Paper pickup roller A D-shaped roller that rotates against the paper and pushes one sheet
into a printer.
Parallel port a peripheral port that is used most often for printer connection and that
transfers data in parallel instead of one bit at a time.
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Parked When the print head is in the locked, resting position.
Partition A logical grouping of data organized to fall under a single drive letter for
primary partitions and multiple drives for extended partitions
Partitioning The process of assigning part or all of a hard drive for use by the computer.
Passive hub a type of hub that electrically connects all network ports together. This type
of hub is not powered.
PCI Express (PCIe) a more advanced expansion-bus standard to compete with AGP that
is backward compatible with PCI.
Peripheral Component Interconnect (PCI) Today’s most popular expansion-bus
standard.
Peripheral interface any port that allows external devices to connect to the computer
system.
Personal computer (PC) any of a class of computer systems that allows a single user to
perform day-to-day personal and business functions, such as word processing and
networking. Also IBM’s original product name for such a computer system.
Pickup rollers See paper pickup roller.
Pickup stepper motor the motor that turns the pickup roller in a printer.
Piconet A Bluetooth network. A Bluetooth-enabled device can communicate with up to
seven other devices in one piconet.
Pins The minute projections that terminate signal lines and, for example, appear on a
male connector at the end of a cable.
Pixels Short for picture elements, pixels are the individual dots that the software
projecting the image is capable of controlling. Viewable screen sizes, such as 1024 × 768,
refer to the number of pixels in a matrix. Contrast with dot phosphors.
Planar board a synonym for motherboard that generally has no processor but instead has
a modular interface for a processor card.
Plenum-rated When referring to coaxial covering, a designation that means the coating
does not produce toxic gas when burned (as PVC does) and is rated for use in air plenums
that carry breathable air.
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Plug and Play BIOS A BIOS that communicates with Plug and Play components to
adapt to their existence without the installation of device drivers
Plug and Play (PnP) a standard set of specifications that were developed by Intel to
enable a computer to detect a new device automatically and install the appropriate driver.
Port See interface.
Portable installation A Windows installation method that installs components needed for
Portable system installations on laptops. It includes such features as power management
and LCD display software.
POTS line A Plain Old Telephone Service line, the original analog technology for phone
lines still in use today for standard phone service.
Power circuits the set of conductive pathways that converts 110V or 220V house current
into the voltages a bubble-jet printer uses (usually 12V and 5V) and distributes those
voltages to the other printer circuits and devices that need it.
Power supply the component that converts AC wall voltages to DC voltages that other
Computer components require. Rated in watts, the power supply must be able to handle
the demand placed on it by these components.
Primary partition the first partition created in an operating system. Primary Rate
Interface (PRI) An ISDN interface known as 23B+D, which means it has
23 B channels and one D channel.
Print buffer a small amount of memory located on the printer used to hold print jobs.
Print consumables Products a printer uses in the print process that must be replaced
occasionally. Examples include toner, ink, ribbons, and paper.
Print media another name for the media being printed on. Examples include paper,
transparencies, and labels.
Printer control circuits Runs a printer’s stepper motors, loads paper, and so on. Monitors
the health of the printer and reports that information back to the computer.
Printer controller assembly a large circuit board in a laser printer that converts signals
from the computer into signals for the various parts in a printer.
Printer-resident fonts that is stored locally in the printer’s onboard memory to speed up
printing.
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Printer ribbon a fabric strip that is impregnated with ink and wrapped around two spools
encased in a cartridge. This cartridge is used in dot-matrix printers to provide the ink for
the print process.
Print heads the part of a printer that creates the printed image. In a dot-matrix printer,
the print head contains the small pins that strike the ribbon to create the image, and in an
ink-jet printer, the print head contains the jets used to create the ink droplets as well as
the ink reservoirs. A laser printer creates images using an electro photographic method
similar to that found in photocopiers and does not have a print head.
Print head alignment the process by which the print head is calibrated for use. A special
utility that comes with the printer software is used to do this.
Print head carriage the component of a bubble-jet printer that moves back and forth
during printing. It contains the physical as well as electronic connections for the print
head and (in some cases) the ink reservoir.
Product activation the process of registering your Windows product with Microsoft to
Ensure you have a licensed copy.
Product key a unique key that you enter into Windows during installation to signal that
you have a licensed copy of the software.
PS/2 ports a mini-DIN connector that is used to connect keyboards and mice, so named
for the IBM Personal System/2, where it was originally seen.
Random access memory (RAM) Memory, usually in chip form, that can be read from or
written to in any order
Resource Anything on a network that clients might want to access or use.
Rasterizing The process of converting signals from the computer into signals for the
various assemblies in a laser printer.
Recovery CD A CD-ROM that comes with a particular model and brand of computer
and
Usually contains an image of the entire Windows installation, along with applications,
utilities, and drivers specifically for that computer. Also called a restoration CD.
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Recovery partition a section of hard drive space, usually on a server, that contains an
exact image of a computer’s files and configuration.
Refresh rate the number of times per second, measured in hertz (Hz), that an electron
gun retraces the image on a screen. Higher refresh rates produce better images to the
human eye. Lower refresh rates can cause headaches and poor-quality images.
Registered jack (RJ) a series of modular jacks usually modified by a numerical dentifier,
Such as RJ-11, which identifies the characteristics of that particular registered jack.
Resolution The number of dots in a square inch used to represent the image to be
scanned or printed. Resolution is measured based on a grid of dots in the horizontal and
vertical planes. For example, a resolution of 600 × 600 dpi indicates the device uses
360,000 dots to represent each square inch of the image.
Restoration CD A CD-ROM that comes with a particular model and brand of computer
and that usually contains an image of the entire Windows installation, along with
applications, utilities, and drivers specifically for that computer. Also called a recovery
CD.
Restore point a copy of your system configuration at a given point in time. Ribbon
cartridge the container that holds the printer ribbon. RIMM The module used to carry
Rambus DRAM. RIMM slot the motherboard slot designed to receive a RIMM.
Riser card a card that has no functional circuitry of its own but that provides connecting
Points for other cards parallel to the motherboard.
safe mode Starts Windows 2000/XP using only basic files and drivers, such as mouse
(except serial mice), monitor, keyboard, mass storage, base video, and default system
services.
Scanner An optical device used to digitize images such as line art or photographs, so
that they can be merged with text by a page-layout or desktop publishing program or
incorporated into a CAD drawing.
Serial communications the transmission of information from computer to computer or
From computer to a peripheral, one bit at a time. Serial communications can be
synchronous and controlled by a clock or asynchronous and coordinated by start and stop
bits embedded in the data stream...
Serial ports Interfaces that connect peripheral components using a serial
communications
Stream. Also a specific term for the ANSI/EIA/TIA-232 ports (formerly RS-232) on a
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PC.
Service packs Major patches or upgrades to the Windows operating system are released
in groups known as service packs.
Single Inline Memory Modules (SIMMs) Memory modules that have mated pins in the
same
Position on each side of the module, each pair performing the same function so that the
module’s pin count considers each pair to be only one pin. Contrast to DIMMs, where
each pin in the pair performs a potentially separate function.
Small Outline DIMM (SoDIMM) A smaller form-factor memory module that is used in
smaller systems, such as laptops. Only MicroDIMMs are currently smaller.
Solid-ink printers a printer that uses ink is in a waxy solid form, rather than in liquid
form. This allows the ink to stay fresh and eliminates problems like spillage.
Southbridge A portion of a motherboard’s overall chipset that is responsible for control
of non-AGP video and other I/O communications, such as serial, parallel, and USB ports.
Standard serial cable a serial cable that is used to connect the serial port of a computer
To that of a modem. The signal lines run straight through a standard cable. Contrast to
null modem serial cable.
Stepper motor a very precise motor that can move in very small increments. Often used
In printers.
Super Video Graphics Array (SVGA) port A DE15F interface that has the capability of
Accepting a wide variety of signals using various screen resolutions.
Swap file also called the page file; the swap file is the virtual memory in Windows.
Switch A Layer 2 device similar to a hub in its port count but more advanced with the
ability to filter traffic based on the destination MAC address of each frame.
159
Syntax The specific structure required by a text-based command to work properly.
Sysprep A utility used to make an image of a computer for installation on other
computers. System board See motherboard.
System memory the primary computer memory that holds instructions and data for
currently executing software
Temporary file (temp file) a file designed to store information for a short period of time
and then be deleted.
Temporary Internet Files A directory on your hard drive where Internet Explorer copies
any images or HTML files from websites you visit frequently. Used to speed up Internet
access.
Text-based commands that are executed from the command prompt, such as
DIR, CD, or FORMAT.
Text mode As opposed to graphics mode, text mode displays only alphanumeric
characters on the screen, not graphical images.
Thermal printer a non impact printer that uses a thermal print head and specially treated
paper to create an image.
Thrashing When you have an extremely slow system and a disk that is constantly being
accessed.
Toner A black carbon substance mixed with polyester resins and iron oxide particles.
During the EP printing process, toner is first attracted to areas that have been exposed to
the laser in laser printers and is later deposited and melted onto the print medium.
Transfer corona assembly the part of an EP process printer that is responsible for
transfer ring the developed image from the EP drum to the paper.
Transferring step the step in the EP print process when the developed toner image on the
EP drum is transferred to the print medium using the transfer corona
Typical installation installs the most commonly used components of the software, but
not all of the components.
Unattended installation an installation method that does not require human intervention
once started, and is frequently used when installing over the network. Unattended
installations use answer files to supply the necessary parameters to Windows Setup.
160
Virtual memory a general term for a type of computer technology where hard disk space
is used to supplement a computer’s physical memory.
Virus A small, deviously genius program that replicates itself to other computers,
generally causing those computers to behave abnormally.
Vulnerability scanner A software application that checks your network for any known
security holes. Watt The unit of measure for power. Used to rate power supplies and the
related requirements of the various powered components.
WiFi Short for wireless fidelity, it is a collection of IEEE 802.11x standards.
Window A rectangular area created on the screen when an application is opened within
Windows.
Windows Catalog A list of all the hardware that works with Windows and which
versions of Windows it works with. The new name for the Hardware Compatibility List.
Windows Update A feature designed to keep Windows current by automatically
downloading updates such as patches and security fixes and installing these fixes
automatically.
Wireless access point (WAP) a central hub that looks nearly identical to wireless
routers, and provide central connectivity like wireless routers, but doesn’t have nearly as
many features. The main one most people are concerned with is Internet connection
sharing.
Wireless Internet An Internet access technology that uses radio frequency signals to
communicate between ISP and user. It allows the user to roam about a particular area
while remaining connected to the Internet.
Wireless cards an adapter card that gives its host the ability to join a wireless LAN.
Working directory an area on the hard disk where programs store their temporary files
while they work.
Workstation 1) in networking, any personal computer (other than the file server) attached
to the network. 2) A high-performance computer optimized for graphics applications such
as computer-aided design, computer-aided engineering, and scientific applications.
Writing step the step in the EP print process during which the items being printed are
Written to the EP drum. In this step, the laser is flashed on and off as it scans across the
surface of the drum. The area on which the laser shines is discharged to almost ground (-
100V).
Chapter - 1........................................................................................................................... 3
Introduction to Computer............................................................................................ 3
Computer................................................................................................................... 3
Power supply ............................................................................................................. 5
Video display controller ........................................................................................... 5
Removable media devices......................................................................................... 5
Secondary storage ..................................................................................................... 6
Sound card................................................................................................................. 6
Other peripherals...................................................................................................... 6
Generations of Computers ....................................................................................... 7
The Five Generations of Computers ....................................................................... 7
First Generation - 1940-1956: Vacuum Tubes ....................................................... 8
Second Generation - 1956-1963: Transistors ......................................................... 8
Third Generation - 1964-1971: Integrated Circuits .............................................. 9
Fourth Generation - 1971-Present: Microprocessors............................................ 9
Fifth Generation - Present and Beyond: Artificial Intelligence.......................... 10
Chapter – 2........................................................................................................................ 13
Computer Hardware .................................................................................................. 13
Part of a P.C. ........................................................................................................... 14
Case .......................................................................................................................... 14
Power Supply........................................................................................................... 15
Mother Board.......................................................................................................... 18
Accounting to Power Supply.................................................................................. 21
Chapter – 3........................................................................................................................ 38
Expansion Slots ........................................................................................................... 38
Micro Channel Architecture.................................................................................. 38
ISA Expansion Slots................................................................................................ 39
AGP Expansion Slots.............................................................................................. 41
RAM Slots................................................................................................................ 44
Chapter – 4........................................................................................................................ 47
Memory........................................................................................................................ 47
Two Types of Memory............................................................................................ 47
ROM (BIOS)............................................................................................................ 48
RAM (Random Access Memory)........................................................................... 50
DRAM (Dynamic) ................................................................................................... 50
SRAM (Static RAM)............................................................................................... 51
Dynamic Random Access Memory........................................................................ 51
Chapter – 5........................................................................................................................ 68
System Buses................................................................................................................ 68
Three types of bus ................................................................................................... 69
CPU (Central Processing Unit).............................................................................. 69
CPU Unit.................................................................................................................. 70
Chapter - 6......................................................................................................................... 75
Monitor ........................................................................................................................ 75
Inside CRT Displays ............................................................................................... 75
Diagram of Monochrome CRT.............................................................................. 76
2
Chapter - 7......................................................................................................................... 77
Printers........................................................................................................................ 77
Printers..................................................................................................................... 77
Image Formation Method ...................................................................................... 77
Fully Formed Character Printers.......................................................................... 77
Printing Mechanism................................................................................................ 78
Daisy Wheel Printer................................................................................................ 80
Chain Printer........................................................................................................... 81
Drum Printers ......................................................................................................... 82
Dot-Matrix Printers ................................................................................................ 83
Color Dot-Matrix Printers ..................................................................................... 84
Chapter - 8......................................................................................................................... 92
Assembling a PC ......................................................................................................... 92
Material Required................................................................................................... 92
Mainframes............................................................................................................ 101
Features.................................................................................................................. 103
Program execution................................................................................................ 103
Interrupts............................................................................................................... 104
Protected mode and supervisor mode................................................................. 104
Memory management........................................................................................... 105
Security .................................................................................................................. 110
Microsoft Windows............................................................................................... 111
Linux/Unix............................................................................................................. 112
Unix and unix-like operating systems ................................................................. 116
Mac OS X............................................................................................................... 117
Hobby development .............................................................................................. 118
Operating Software Installation .......................................................................... 123
What can be Upgrade? ......................................................................................... 124
Microsoft................................................................................................................ 126
Chapter - 9....................................................................................................................... 128
Windows shortcut Key ............................................................................................. 128
Windows shortcut key .......................................................................................... 128
XP Run Commands .............................................................................................. 132
Chapter-10....................................................................................................................... 142
Some Sort Form ........................................................................................................ 142
3
Chapter - 1
Introduction to Computer
Computer
C: - Common
O: - Operating
M: - Machine
P: - Particular
U: - Useful
T: - Trading/Training
E: - Education
R: - Research
A personal computer is made up of multiple physical components of computer
hardware, upon which can be installed an operating system and a multitude of software
to perform the operator's desired functions.
Hardware of a modern Personal Computer.
1. Monitor
2. Motherboard
3. CPU
4. RAM Memory
5. Expansion card
6. Power supply
7. Optical disc drive
8. Hard Disk
9. Keyboard
10. Mouse
4
Inside a custom computer.
Though a PC comes in many different forms, a typical personal computer consists of a
case or chassis in a tower shape (desktop) and the following parts:
The motherboard is the main component inside the case. It is a large rectangular board
with integrated circuitry that connects the rest of the parts of the computer including the
CPU, the RAM, the disk drives (CD, DVD, hard disk, or any others) as well as any
peripherals connected via the ports or the expansion slots. Computer Hardware course is
very important for the future because they are now essential in business.
Components directly attached to the motherboard include:
The central processing unit (CPU) performs most of the calculations which
enable a computer to function, and is sometimes referred to as the "brain" of the
computer. It is usually cooled by a heat sink and fan.
The chip set mediates communication between the CPU and the other
components of the system, including main memory.
RAM Stores all running processes (applications) and the current running OS.
RAM Stands for Random Access Memory
The BIOS includes boot firmware and power management. The Basic Input
Output System tasks are handled by operating system drivers.
Internal Buses connect the CPU to various internal components and to expansion
cards for graphics and sound.
o Current
The north bridge memory controller, for RAM and PCI Express
PCI Express, for expansion cards such as graphics and physics
processors, and high-end network interfaces
PCI, for other expansion cards
SATA, for disk drives
o Obsolete
ATA (superseded by SATA)
AGP (superseded by PCI Express)
VLB VESA Local Bus (superseded by AGP)
ISA (expansion card slot format obsolete in PCs, but still used in
industrial computers)
External Bus Controllers support ports for external peripherals. These ports may
be controlled directly by the south bridge I/O controller or based on expansion
cards attached to the motherboard through the PCI bus.
o USB
o FireWire
o SATA
o SCSI
5
Power supply
A power supply unit (PSU) is the component that supplies power to the other components
in a computer. More specifically, a power supply unit is typically designed to convert
general-purpose alternating current (AC) electric power from the mains (100-127V in
North America, parts of South America, Japan, and Taiwan; 220-240V in most of the rest
of the world) to usable low-voltage DC power for the internal components of the
computer. Some power supplies have a switch to change between 230 V and 115 V.
Other models have automatic sensors that switch input voltage automatically, or are able
to accept any voltage between those limits. It’s divert high voltage into low voltage
Video display controller
Produces the output for the computer monitor. This will either be built into the
motherboard or attached in its own separate slot (PCI, PCI-E, PCI-E 2.0, or AGP), in the
form of a graphics card.
Removable media devices
CD (compact disc) - the most common type of removable media, suitable for
music and data.
o CD-ROM Drive - a device used for reading data from a CD.
o CD Writer - a device used for both reading and writing data to and from a
CD.
DVD (digital versatile disc) - a popular type of removable media that is the same
dimensions as a CD but stores up to 12 times as much information. It is the most
common way of transferring digital video, and is popular for data storage.
o DVD-ROM Drive - a device used for reading data from a DVD.
o DVD Writer - a device used for both reading and writing data to and from
a DVD.
o DVD-RAM Drive - a device used for rapid writing and reading of data
from a special type of DVD.
Blu-ray Disc - a high-density optical disc format for data and high-definition
video. Can store 70 times as much information as a CD.
o BD-ROM Drive - a device used for reading data from a Blu-ray disc.
o BD Writer - a device used for both reading and writing data to and from a
Blu-ray disc.
o
HD DVD - a discontinued competitor to the Blu-ray format...
Floppy disk - an outdated storage device consisting of a thin disk of a flexible
magnetic storage medium. Used today mainly for loading RAID drivers.
6
Iomega Zip drive - an outdated medium-capacity removable disk storage system,
first introduced by Iomega in 1994.
USB flash drive - a flash memory data storage device integrated with a USB
interface, typically small, lightweight, removable, and rewritable. Capacities vary,
from hundreds of megabytes (in the same ballpark as CDs) to tens of gigabytes
(surpassing, at great expense, Blu-ray discs).
Tape drive - a device that reads and writes data on a magnetic tape, used for long
term storage and backups.
Secondary storage
Hardware that keeps data inside the computer for later use and remains persistent even
when the computer has no power.
Hard disk - for medium-term storage of data.
Solid-state drive - a device similar to hard disk, but containing no moving parts
and stores data in a digital format.
RAID array controller - a device to manage several internal or external hard disks
and optionally some peripherals in order to achieve performance or reliability
improvement in what is called a RAID array.
Sound card
Enables the computer to output sound to audio devices, as well as accept input from a
microphone. Most modern computers have sound cards built-in to the motherboard,
though it is common for a user to install a separate sound card as an upgrade. Most sound
cards, either built-in or added, have surround sound capabilities.
Other peripherals
In addition, hardware devices can include external components of a computer system.
The following are either standard or very common.
Wheel Mouse
Includes various input and output devices, usually external to the computer system.
7
Input
Text input devices
o Keyboard - a device to input text and characters by depressing buttons
(referred to as keys), similar to a typewriter. The most common Englishlanguage
key layout is the QWERTY layout.
Pointing devices
o Mouse - a pointing device that detects two dimensional motion relative to
its supporting surface.
o Optical Mouse - a newer technology that uses Light to track the surface
under the mouse to determine the motion to be translated into cursor
movements on the screen.
o Trackball - a pointing device consisting of an exposed protruding ball
housed in a socket that detects rotation about two axes.
Gaming devices
o Joystick - a general control device that consists of a handheld stick that
pivots around one end, to detect angles in two or three dimensions.
o Gamepad - a general handheld game controller that relies on the digits
(especially thumbs) to provide input.
o Game controller - a specific type of controller specialized for certain
gaming purposes.
Image, Video input devices
o Image scanner - a device that provides input by analyzing images, printed
text, handwriting, or an object.
o Webcam - a low resolution video camera used to provide visual input that
can be easily transferred over the internet.
Audio input devices
o Microphone - an acoustic sensor that provides input by converting sound
into electrical signal
Generations of Computers
First Generations (1940-1956) Vacuum Tube
Second Generations (1956-1963) Transistors
Thirds Generations (1964-1971) I.C.
Fourth Generations (1971- Present)
Fifth Generations (Present and Beyond)
The Five Generations of Computers
8
The history of computer development is often referred to in reference to the
different generations of computing devices. Each generation of computer is characterized
by a major technological development that fundamentally changed the way computers
operate, resulting in increasingly smaller, cheaper, and more powerful and more efficient
and reliable devices.
First Generation - 1940-1956: Vacuum Tubes
The first computers used vacuum tubes for circuitry and magnetic drums for memory,
and were often enormous, taking up entire rooms. They were very expensive to operate
and in addition to using a great deal of electricity, generated a lot of heat, which was
often the cause of malfunctions. First generation computers relied on machine language,
the lowest-level programming language understood by computers, to perform operations,
and they could only solve one problem at a time. Input was based on punched cards and
paper tape, and output was displayed on printouts. The UNIVAC and ENIAC computers
are examples of first-generation computing devices. The UNIVAC was the first
commercial computer delivered to a business client, the U.S. Census Bureau in 1951
Vacum Tube
Second Generation - 1956-1963: Transistors
Transistors replaced vacuum tubes and ushered in the second generation of computers.
The transistor was invented in 1947 but did not see widespread use in computers until the
late 50s. The transistor was far superior to the vacuum tube, allowing computers to
become smaller, faster, cheaper, more energy-efficient and more reliable than their firstgeneration
predecessors. Though the transistor still generated a great deal of heat that
subjected the computer to damage, it was a vast improvement over the vacuum tube.
Second-generation computers still relied on punched cards for input and printouts for
output. Second-generation computers moved from cryptic binary machine language to
9
symbolic, or assembly, languages, which allowed programmers to specify instructions in
words. High-level programming languages were also being developed at this time, such
as early versions of COBOL and FORTRAN. These were also the first computers that
stored their instructions in their memory, which moved from a magnetic drum to
magnetic core technology. The first computers of this generation were developed for the
atomic energy industry
Third Generation - 1964-1971: Integrated Circuits
The development of the integrated circuit was the hallmark of the third generation of
computers. Transistors were miniaturized and placed on silicon chips, called
semiconductors, which drastically increased the speed and efficiency of computers.
Instead of punched cards and printouts, users interacted with third generation computers
through keyboards and monitors and interfaced with an operating system,
which allowed the device to run many different applications at one time with a central
program that monitored the memory. Computers for the first time became accessible to a
mass audience because they were smaller and cheaper than their predecessors.
Fourth Generation - 1971-Present: Microprocessors
The microprocessor brought the fourth generation of computers, as thousands of
integrated circuits were built onto a single silicon chip. What in the first generation filled
an entire room could now fit in the palm of the hand. The Intel 4004 chip, developed in
1971, located all the components of the computer - from the central processing unit and
memory to input/output controls - on a single chip. In 1981 IBM introduced its first
10
computer for the home user, and in 1984 Apple introduced the Macintosh.
Microprocessors also moved out of the realm of desktop computers and into many areas
of life as more and more everyday products began to use microprocessors. As these small
computers became more powerful, they could be linked together to form networks, which
eventually led to the development of the Internet. Fourth generation computers also saw
the development of GUIs, the mouse and handheld devices.
Fifth Generation - Present and Beyond: Artificial Intelligence
Fifth generation computing devices, based on artificial intelligence, are still in
development, though there are some applications, such as voice recognition, that are
being used today. The use of parallel processing and superconductors is helping to make
artificial intelligence a reality. Quantum computation and molecular and nanotechnology
will radically change the face of computers in years to come. The goal of fifth-generation
computing is to develop devices that respond to natural language input and are capable of
learning and self-organization
Some generation of Computer
Year Events
1971
The 4004-the first 4-bit microprocessor-is introduced by Intel. It boasts 2000
transistors with a clock speed of up to 1 MHz (megahertz).
1972 The first 8-bit microprocessor-the 8008-is released.
11
1974
The 8080 microprocessor is developed. This improved version of the 8008 becomes
the standard from which future processors will be designed.
1975
Digital Research introduces CP/M-an operating system for the 8080. The
combination of software and hardware becomes the basis for the standard
computer.
1976
Zilog introduces the Z80-a low-cost microprocessor (equivalent to the 8080).
The Apple I come into existence, although it is not yet in wide use.
1977
The Apple II and the Commodore PET computers, both of which use a 6502
processor, are introduced. These two products become the basis for the home
computer. Apple's popularity begins to grow.
1978
Intel introduces a 16-bit processor, the 8086, and a companion math coprocessor,
the 8087.
Intel also introduces the 8088. It is similar to the 8086, but it transmits 8 bits at a
time.
1980
Motorola introduces the 68000-a 16-bit processor important to the development of
Apple and Atari computers. Motorola's 68000 becomes the processor of choice for
Apple.
1981
The IBM personal computer (PC) is born; it contains a 4.7-MHz 8088 processor, 64
KB (kilobytes) of RAM (random access memory) and is equipped with a version of
MS-DOS 1.0 (three files and some utilities). Available mass-storage devices
include a 5.25-inch floppy drive and a cassette tape drive.
1982
Intel completes development of the 80286-a 16-bit processor with 150,000
transistors.
MS-DOS 1.1 now supports double-sided floppy disks that hold 360 KB of data.
1983
IBM introduces the XT computer with a 10-MB hard-disk drive.
MS-DOS 2.0 arrives-it features a tree-like structure and native support for harddisk
drive operations.
1984
The first computer with an 80286 chip-the IBM AT-enters the market. It is a 6-
MHz machine with a 20-MB hard-disk drive and a high-density, 1.2-MB 5.25-inch
floppy-disk drive.
1985 MS-DOS 3.2, which supports networks, is released.
1986
The first Intel 80386-based computer is introduced by Compaq; it features a 32-bit
processor with expanded multitasking capability (even though no PC operating
12
system yet fully supports the feature).
1987
MS-DOS 3.3 arrives, allowing use of 1.44-MB 3.5-inch floppy-disk drives and
hard-disk drives larger than 32 MB.
1988
IBM introduces the PS/2 computer series. A complete departure from previous
machines, its proprietary design does not support the hardware and software
available on IBM PCs or clones.
Microsoft (with the help of IBM) develops OS/2 (Operating System 2), which
allows 32-bit operations, genuine multitasking, and full MS-DOS compatibility.
Microsoft releases MS-DOS 4.0.
1989
Intel introduces the 80486 processor; it contains an on-board math coprocessor and
an internal cache controller (offering 2.5 times the performance of a 386 processor
with a supporting coprocessor).
1991 MS-DOS 5.0 offers a significantly improved DOS shell.
1992
The Intel i586 processor, the first Pentium, is introduced, offering 2.5 times the
performance of a 486.
IBM expands OS/2, and Microsoft Windows is introduced.
1993
MS-DOS 6.0 arrives. The term "multimedia" (the inclusion of CD-ROM drives,
sound cards, speakers, and so forth, as standard equipment on new personal
computers) comes into use.
1994
Intel delivers the first 100-MHz processor. COMPAQ Computer Corporation
becomes the largest producer of computers.
1995
Windows 95, code-named Chicago, is introduced by Microsoft. It features 32-bit
architecture.
IBM has now shipped over one million OS/2 Warp software packages.
The Internet, having expanded far beyond its beginnings as a network serving
government and university institutions, is now in everyday use by the rapidly
growing population with access to a modem.
Computer prices drop as performance increases. IBM purchases Lotus (maker of
the popular Lotus1-2-3 spreadsheet).
1995-
1996
Software manufacturers scramble to make their products compatible with Windows
95.
1997
Microprocessor speeds exceed the 200-MHz mark. Hard-disk drive and memory
prices fall while basic system configuration sizes continue to increase.
13
CD-ROM drives and Internet connections have become standard equipment for
computers.
1998
Personal computer performance continues to soar, and PC prices continue to fall.
CPU speeds exceed 450 MHz, and motherboard bus speeds reach 100 MHz.
Multimedia and Internet connections have become the de facto standard for new
PCs.
Entry-level machines are priced near the $500 mark.
Universal Serial Bus (USB) is introduced.
Windows 98 becomes the standard operating system for most new personal
computers.
1999
Processors exceed 600 MHz.
Microsoft readies Windows 2000 for release in February 2000, as Internet shopping
doubles over the holiday season.
Chapter – 2
Computer Hardware
14
Computer Hardware: - Computer Hardware is the physically part of computer,
including its digital circuitry as distinguished from the computer software that execution
within the Hardware
Computer Hardware:-The mechanical, magnetic, electronic, and electrical components
making up a computer system
Computer Hardware:-Devices capable of accepting and storing computer data,
executing a systematic sequence of operations on computer data, or producing control...
.
PC?
A personal computer (PC) is a computing device made up of many distinct electronic
components that all function together in order to accomplish some useful task (such as
adding up the numbers in a spreadsheet or helping you write a letter). Each component has
a very specific function
Part of a P.C.
The Case
The Power Supply
The Mother Board
The C.P.U.
Memory
Storage Devices
Onboard Disk drive connectors
Display Devices
Ports and Cables
Case
A computer case is the enclosure that encases all the components of a computer. All the
computer components mount to the inside the case -Case is essentially the mounting
platform far all the electronic devices platform for all the electronic devices the make up
the computer.
15
Types of Case
Full Tower 20 – 25 inch 5 or more Draw base
Mid Tower 16 – 19 inch 3 or 4 draw base
Mini Tower 12-15 inch 2 or 3 Draw base
Midi (Musical Instrument Digital interface) between mid and Mini
Desktop 5 to 7 inch 3 Draw Base
Slim line Very Small
Proprietary Case Depend on Company
Power Supply
SMPS (Switch Mode Power Supply) SMPS is the device in the computer that provides
the power supply in the computer because the computer components would not be able to
operate without power supply. It Converts AC into DC.
16
Types of Power Supply
AT (Advance Technology)
Power Connector 12 Pin (6+6)
Floppy Power Connector 4 Pin (Berg)
HDD/CDD Power Connector 4 Pin (Molex)
ATX (Advanced Technology Extended)
Power Connector 20 Pin
FDD Connector 4 Pin (Berg)
HDD/CDD 4 Pin (Molex)
Extra CPU Power 4 Pin
17
MATX (Macro Advanced Technology Extended)
Power Connector 20+4 = 24 Pin
FDD Connector 4 Pin (Berg)
HDD/CDD/DVD 4 Pin (Molex)
HDD/DVD 15 Pin (SATA)
Extra CPU Power 4 Pin
FDD Power Connector(Berg)
18
HDD/CDD/DVD power Connector (Molex)
SATA Power Connector
Mother Board
19
It is the most important components in the computer because it connects all the other
components of a PC together. The spine of the computer is the motherboard, otherwise
known as the system board
A motherboard is the central printed circuit board (PCB) in some complex electronic
systems, such as modern personal computers. The motherboard is sometimes
alternatively known as the main board, system board, or, on Apple computers, the logic
board. It is also sometimes casually shortened to mobo
Second Name
System board
Planner board
Logic board
Mother board
Mobo
20
Modern motherboards include, at a minimum:
Sockets (or slots) in which one or more microprocessors are installed
Slots into which the system's main memory is installed (typically in the form of DIMM
modules containing DRAM chips)
A chipset which forms an interface between the CPU's front-side bus, main memory, and
peripheral buses
Non-volatile memory chips (usually Flash ROM in modern motherboards) containing the
system's firmware or BIOS
Slots for expansion cards (these interface to the system via the buses supported by the
chipset)
Power connectors’ flickers, which receive electrical power from the computer power
supply and distribute it to the CPU, chipset, main memory, and expansion cards
Types of Mother Board
Accounting to integrate
Non–Integrated: - Each major assembly is installed in the computer as an expression
card. Non integrated boards can be easily identified because each expression slot is
usually occupied by one of the components. It is difficult to find nonintegrated
motherboards these days. Many of what would normally be called nonintegrated system
boards now incorporate the most commonly used circuitry (such as IDE and floppy
controllers, serial controllers, and sound cards) onto the motherboard itself. In the early
1990s, these components had to be installed externally to the motherboard.
21
Integrated Motherboard: -
Most of the components that would otherwise be installed as expansion are integrated
into the motherboard circuitry. Integrated system boards were designed for simplicity. Of
course, there’s a drawback to this simplicity: When one component breaks, you can’t just
replace the component that’s broken; the whole motherboard must be replaced. Although
these boards are cheaper to produce, they are more expensive to repair. With integrated
system boards, there is a way around having to replace the whole motherboard when a
single component breaks. On some motherboards, you can disable the malfunctioning
onboard component (for example, the sound circuitry) and simply add an expansion card
to replace its functions.
Accounting to Power Supply
XT (Extended Technology) Motherboard
CPU used with this mother board like: - 8085 8086 8087 8088
Ram used 1MB
IRQ 8(Interrupt Request Query)
DMA 4(Direct Memory Access)
Power Connector 9 Pin and 6+6 = 12 Pin
Not used in these days
All supporting components in the form of IC
22
AT (Advanced Technology) Motherboard
CPU used with this motherboard like 80286, 80386, 80486, P1 and P2
16 bit ISA slots (Industry Standard Architecture)
RAM used: - 8, 16, 32 MB
Special Slot for RAM
S1mm:- Single inline Memory Module
IRQ: - 16
DMA: - 8
Power Connector: - 6+6 = 12 Pin
23
ATX (Advanced Technology Extended) Motherboard
CPU used with this board like: - P2, P3 and P4
32 bit PCI slots (Peripheral Components Interconnects)
IRQ: - 16
DMA: - 8
Used in these days
Special slots for RAM
DIMM: - Dual Inline Memory Module
Power Connector 20 Pin
MATX (Macro Advanced Technology Extended)
CPU used with this board: - P4
32 bit 64 bit PCI slots
Used in these days
DIMM slots for RAM
Power Connector:-24 Pin (20 + 4)
24
NLX (New Low-profile Extended)
New Low-profile Extended is used in some low-profile case types. NLX continues the
trend of the technology it succeeded, Low Profile Extended (LPX), placing the expansion
slots (ISA, PCI, and so on) sideways on a special riser card to use the reduced vertical
space optimally. Fairly new motherboard Expansions slots are placed on the board as a
riser card. Not so durable.
25
Balanced Technology Extended (BTX)
In 2003, Intel announced its design for a new motherboard, slated to hit the market mid- to
Late-2004.When that time came; the new BTX motherboard was met with mixed
Emotions.
According to Position
Desktop Types: - These types of motherboard are placed on the cabinet horizontal like: -
P1 and P2
26
Tower Types: - These types of motherboard are placed on the cabinet vertically
like P3, P4
Most Visible Parts of Motherboard
Chipsets (Bridges)
CPU Socket
RAM Slots
Power Connectors
HDD/CDD and FDD Connector
Expansion Slots and Sockets
CMOS (Complementary Metal Oxide Semi Conductor)
BIOS (Basic Input Output System)
Back Panel
27
CPU Socket
Keyboard Connector
DIN (Dutch Industry Nome)
PS/2 Port (Keyboard and Mouse)
28
USB Port
Rj-45
Rj-11
Parallel Port
Serial Port
Parallel Port
29
SATA Port
IDE Connector
Serial and Parallel Port
30
Mouse Ports
Back panel of Computer
31
LPT (Line Printing Terminal)
Graphic Card
32
LAN Card
TV Tuner Card
33
Sound Card
Modem
34
IDE Connector
35
Chipsets
A chipset is a collection of chips or circuits that perform interface and peripheral functions
for the processor. This collection of chips is usually the circuitry that provides interfaces
for memory, expansion cards, and onboard peripherals and generally dictates how a
motherboard will talk to the installed peripherals.
Northbridge (B)
The Northbridge subset of a motherboard’s chipset is the set of circuitry or chips that
performs one very important function: management of high-speed peripheral
communications. The Northbridge subset is responsible primarily for communications
with integrated video using AGP and PCIe, for instance, and processor-to-memory
communications.
Southbridge(C)
The Southbridge chipset, as mentioned earlier, is responsible for providing support to the
myriad onboard peripherals (PS/2, Parallel, IDE, and so on), managing their
communications with the rest of the computer and the resources given to them.
36
Mother Board Connector
BIOS (Basic input output system) Aside from the processor, the most important chip on
the motherboard are the Basic Input/ Output System (BIOS) chip. This special memory
chip contains the BIOS software that tells the processor how to interact with the rest of
the hardware in the computer. The BIOS chip is easily identified: If you have a non-clone
computer (Compaq, IBM, HP, and so on), this chip has on it the name of the
manufacturer and usually the word BIOS. For example, the BIOS chip for a Compaq has
something like Compaq BIOS printed on it. For clones, the chip usually has a sticker or
printing on it from one of the major BIOS manufacturers (AMI, Phoenix/Award, Win
bond, and so on).
37
BIOS
CMOS
(Complementary Metal Oxide Semi-Conductor) save Date Time Hardware
Configuration and memory, CMOS is a Special kind of memory that holds the BIOS
configuration setting
Your PC has to keep certain settings when it’s turned off and its power cord is
unplugged.
These settings include the following:
Date
Time
Hard drive configuration Memory
To keep its settings, the memory must have power constantly. When you shut off a
computer, anything that is left in main memory is lost forever. To prevent CMOS from
losing its information (and it’s rather important that it doesn’t), motherboard
manufacturers include a small battery called the CMOS Battery to power the CMOS
memory. The batteries come in different shapes and sizes, but they all perform the same
function. Most CMOS batteries look like either large watch batteries or small, cylindrical
batteries.
38
Chapter – 3
Expansion Slots
An Extension of the main computer bus that include expansion slots for use by
compatible adapter such as memory board video adapter card hard disk controller and
SCSI interface card .The slots are used to install various devices in the computer to
expend its capabilities like: - VGA, NIC, Sound, USB, and TV Tuner Card
Some Slots on Motherboard:-EISA, MCA, ISA, PCI, AMR, CNR, AGP
The Extended Industry Standard Architecture (in practice almost always shortened to
EISA and frequently pronounced "eee-suh") is a bus standard for IBM compatible
computers. It was announced in late 1988 by PC clone vendors (the "Gang of Nine") as a
counter to IBM's use of its proprietary Micro Channel Architecture (MCA) in its PS/2
series
Year created: 1988
Width in bits: 32
Number of devices: 1 per slot
Capacity 8.33 MHz
Style: Parallel
Micro Channel Architecture
Micro Channel Architecture (in practice almost always shortened to MCA) was a
proprietary 16- or 32-bit parallel computer bus created by IBM in the 1980s for use on
their new PS/2 computers.
39
ISA Expansion Slots
If you have a computer made before 1997, chances are the motherboard has a few
Industry Standard Architecture (ISA) expansion slots. They’re easily recognizable
because they are usually black and have two parts: one shorter and one longer. Computers
made after 1997 generally include a few ISA slots for backward compatibility with old
expansion cards
CPU Supported 8088, 80286 and Pentium 1
Width in Bits 8 or16 bit
Color Black
Pin 62
Cut without Cut/One Cut
Capacity 4, 6, 8 MHz
Style Parallel
ISA Slots
40
PCI Expansion Slots
Most computers made today contain primarily Peripheral Component Interconnect
(PCI) Slots. They are easily recognizable because they are short (around 3 inches long)
and usually white. PCI slots can usually be found in any computer that has a Pentiumclass
processor or higher
Color:-White, Yellow, Green
Year created July 1993
CPU Supported Up to Pentium 2
Width in Bits 32 or 64
Color White
Capacity 133 MB/s (32bit)
Pin 62
Cut One Cut
Style Parallel
PCI Slots
41
PCIe Expansion Slots
The newest expansion slot architecture that is being used by motherboards is PCI Express
(PCIe). It was designed to be a replacement for AGP and PCI. It has the capability of
being faster than AGP while maintaining the flexibility of PCI. And motherboards with
PCIe will have regular PCI slots for backward compatibility with PCI.
PCI Express Slot
AGP Expansion Slots
Accelerated Graphics Port (AGP) slots are very popular for video card use. In the past,
if you wanted to use a high-speed, accelerated 3D graphics video card, you had to install
the card into an existing PCI or ISA slot. AGP slots were designed to be a direct
connection between the video circuitry and the PC’s memory. They are also easily
recognizable because they are usually brown, are located right next to the PCI slots on the
motherboard, and are shorter than the PCI slots.
Year created 1997
Width in bits 32
Capacity up to 2133 MB/s
Style Parallel
Cut One Cut
Color Brown
Version AGP 1x, AGP 2x, AGP 4x, AGP 8x
42
AMR Expansion Slots (Audio Modem Riser)
The manufacturers developed a way of separating the analog circuitry, for example,
modem and analog audio, onto its own card. This allowed the analog circuitry to be
separately certified. This slot and riser card technology was known as the Audio Modem
Riser
Color Brown
Cut One Cut
Pin 46
Used up to P3
43
CNR Expansion Slots
The Communications and Networking Riser (CNR) slots that can be found on some
Intel motherboards are a replacement for Intel’s AMR slots. Essentially, these 60-pin slots
allow a motherboard manufacturer to implement a motherboard chipset with certain
integrated features
Color Yellow, Brown
Bits 64 bit
Cut One Cut
Pin 60
Only for mATX
44
RAM Slots
DIPP (Dual Inline Pin Package)
Used with 8085, 8086, 8087, 8088 CPU
Look like IC
Storage capacity small
Took hours populating boards
Time-consuming and labor-intensive
Chip creep -they crept out of their sockets over time as the system went through thermal
cycles
SIPP (Single Inline Pin Package)
Used with 80286, 80386 CPU
Placed on motherboard vertically
Also small capacity
Little tiny wires for individual sockets
The wires would bend
Their omitted
45
SIMM (Single Inline Memory Module)
White Slots
RAM used in these slots
One cut and without cut slots
30 Pin and 72 Pin Packages
DIMM (Dual Inline Memory Module)
Used with p3 and P4 CPU
168(SDRam) and 184(DDR1) or 240(DDR2) pin
Color Black
Available in One Cut (DDRam) And Two Cut (SDRam)
Separate row of signal pins on each side
More than 200 signal pins
46
RIMM (Rambus Inline Memory Module)
Have different signal pins on each side
Mostly obsolete
Fairly new Slots for Ram
188 pin
Color Black
Two Cut
Used Only Server type Board
47
Chapter – 4
Memory
It is use to store information and instruction for CPU while program has been execute.
Memory is temporary storage because when the power is removed the information the
memory was holding disappear Computer memory refers to devices that are used to store
data or programs (sequences of instructions) on a temporary or permanent basis for use in
an electronic digital computer.
Two Types of Memory
Primary Secondary
ROM RAM
S. Ram D. Ram Storage Device
MROM L1 DIP HDD, CDD, FDD
PROM L2 SIP Pen Drive, FDD
EP ROM L3 FPM Tape Drive
EEP ROM EDO
SD RAM
DD RAM
RD RAM
ROM (BIOS): - ROM or Read Only Memory hold sets of instructions which tell the
MPU what to do, for instance a ROM will tell the CPU how to recognize key and which
key is to be pressed and how to light up the screen. Information stored on a ROM can be
read and can not be rubbed. It is permanently build in computer at the time of its
productions known as firmware.
Non-volatile memory
ROM and RAM are NOT opposites.
Main ROM BIOS is contained in a ROM chip on the motherboard.
There also found in adapter cards and removable storage.
Today, we use a type of ROM called EEPROM or Flash ROM.
48
In general, a PC can be fitted with up to five or more BIOS ROMs
System (Motherboard) BIOS
Video BIOS
Drive-controller BIOS
Network-adapter board BIOS
SCSI-adapter BIOS
Specialty software manufacturers, who make BIOS chips, supply the ROM chips.
The Primary suppliers are
Phoenix
AMI (American Mega trends)
Award
ROM (BIOS)
MROM: - (Masked ROM)
It stores instruction and data for MPU. It stored the bit of binary information,
programmed at the factory.
P ROM: - (Programmable ROM)
This is a type of ROM that can be programmed using special equipment; it can be written
to, but only once. This is useful for companies that make their own ROMs from software
they write, because when they change their code they can create new PROMs without
requiring expensive equipment, can be custom-programmed by the user (once) using
special circuitry.
49
EP ROM (Erasable Programmable ROM)
An EPROM is a ROM that can be erased and reprogrammed. A little glass window is
installed in the top of the ROM package, through which you can actually see the chip that
holds the memory. Ultraviolet light of a specific frequency can be shined through this
window for a specified period of time, which will erase the EPROM and allow it to be
reprogrammed again. Obviously this is much more useful than a regular PROM, but it
does require the erasing light.
.
50
EEP ROM (EA ROM) Electrically Alterable ROM
The next level of erase ability is the EEPROM, which can be erased under software
control. This is the most flexible type of ROM, and is now commonly used for holding
BIOS programs. When you hear reference to a "flash BIOS" or doing a BIOS upgrade by
"flashing", this refers to reprogramming the BIOS EEPROM with a special software
program. Here we are blurring the line a bit between what "read-only" really means, but
remember that this rewriting is done maybe once a year or so, compared to real readwrite
memory (RAM) where rewriting is done often many times per second! , can also be
programmed and erased by the user using ultraviolet light and special circuitry external to
the computer. , can be erased and reprogrammed by special circuitry within the computer.
RAM (Random Access Memory)
RAM is designed to act as short term memory and therefore also know as volatile
memory. A RAM holds information which is needed for a particular operating.
Types of RAM
DRAM (Dynamic)
Requires that data be refreshed (essentially rewritten) every millisecond
Industry-standard refresh time is 15ms
Refresh occurs when the memory controller accesses all the rows of data in the memory
chip.
DRAM uses only 1 transistor and 1 capacitor pair per bit
Available with one billion or more transistors
Tiny capacitors must retain their charge, or memory will be lost
The DRAM chip mostly is used for the main memory
Very dense (pack a lot of bits into a very small chip)
Inexpensive
Unfortunately it’s very slow
51
SRAM (Static RAM)
Consists of levels of Cache
L1 (internal cache):–Always built into the processor die.
L2 (external cache):-Originally installed on the motherboard but now on the processor
die running at full core speed.
L3 –Is present in high-end workstations and server processors (Pentium 4 Extreme
Edition).
Dynamic Random Access Memory
DIP (Dual Inline Package)
Took hours populating boards
Time-consuming and labor-intensive
Chip creep -they crept out of their sockets over time as the system went through thermal
cycles
DIPP Slot Ram
SIPP (Single Inline Pin Package)
Little tiny wires for individual sockets
The wires would bend
Their omitted
52
SIPP was a type of random access memory. Its name stands for Single Inline Pin Package
.It consisted of a small printed circuit board upon which were mounted a number of
memory chips. It had 30 pins along one edge which mated with matching holes in the
motherboard of the computer. This type of memory was used in 80286 and 386SX
systems. It was later replaced by SIMMs, which proved to be easier to install.30-pin SIPP
modules were pin compatible with 30-pin SIMM modules explaining why some SIPP
modules were in fact SIMM modules with pins soldered onto the connectors.
FPM (Fast Page Memory)
CPU used with 486/Pentium
30 Pin
8 bit
No Cut
SIMM Slots
53
EDO (Extended Data out RAM)
72 pin
32 bit
Introduced in 1995
SIMM Slot
One cut
Up to P1
SD RAM (Synchronous Data RAM)
Speed:-66 MHz, 100 MHz, 133 MHz
Introduce in 1996
2 Cut
DIMM Slots
Used up to PIII
Pin: - 168 Pin
54
DDR (Dual Data RAM)
Speed 100 MHz, 200 MHz, 300 MHz, 530 MHz
1 Cut
DIMM slots
Used with PIV
Pin 184 Pin (DDR2:- 240)
DDR-1 Ram
DDR2 SDRAM is a Double Data Rate Synchronous Dynamic Random Access
Memory interface. It supersedes the original DDR SDRAM specification and the two are
not compatible. In addition to double pumping the data bus as in DDR SDRAM,
(transferring data on the rising and falling edges of the bus clock signal), DDR2 employs
an I/O buffer between the memory and the data bus so that the data bus can be run at
twice the speed of the memory clock. The two factors combine to achieve a total of 4 data
transfers per memory clock cycle.
55
DDR3 SDRAM or Double-Data-Rate Three Synchronous Dynamic Random Access
Memory is a random access memory interface technology used for high bandwidth
storage of the working data of a computer or other digital electronic devices. DDR3 is
part of the SDRAM family of technologies and is one of the many DRAM (dynamic
random access memory) implementations.
RD RAM (RAM Bus Data RAM)
Direct Rambus DRAM or DRDRAM (sometimes just called Rambus DRAM or
RDRAM) is a type of synchronous dynamic RAM, designed by the Rambus Corporation.
Speed:-400 MHz , 533 MHz, 600 and 800 MHz
2 Cut
RIMM Slots
Pin 188
Used in Server type CPU
56
Chapter -5
Storage Device
Almost every computer made today uses some type of disk drive to store data and
programs until they are needed. Most drives need a connection to the motherboard so the
computer can “talk” to the disk drive. These connections are known as drive interfaces,
and there are two main types: floppy drive interfaces and hard disk interfaces. Floppy disk
interfaces allow floppy disk drives (FDD) to be connected to the motherboard and,
similarly, hard disk inter-faces do the same for hard disks. When you see them on the
motherboard, these interfaces are said to be onboard, as opposed to being on an expansion
card (off-board). The interfaces consist of circuitry and a port. Most motherboards
produced today include both the floppy disk and hard disk interfaces on the motherboard.
Today, the headers you will find on most motherboards are for Enhanced IDE
(EIDE/PATA) or Serial ATA (SATA). Advanced Technology Attachment (ATA) is the
standard term for what is more commonly referred to as Integrated Drive Electronics
(IDE). The AT component of the name was borrowed from the IBM PC/AT, which was
the standard of the day. However, because ATA is not the only technology that integrates
the drive controller circuitry into the drive assembly (ESDI, for example, was another),
IDE is somewhat of a misnomer and not the best term when referring only to ATA drives.
Storage media hold the Data being accessed as well as the file system need to operate and
data that to be saved
HDD: - (Hard Disk Drive) Hard disk system are used for permanent storage and quick
access .hard disk typically reside the computer and can hold the information than other
form of storage
Three types of HDD
ATA (Advanced Technology Attachment)
Power Cable:-4pin
Data Cable:-40 Pin
SATA (Serial Advanced technology Attachment)
Power cable:-15 pin
Data cable:-7 Pin
SCSI (Small Computer System Interface)
Power cable:-4 pin
Data cable:-50/68 Pin
FDD:- (Floppy Disk Drive) A floppy disk is a magnetic storage medium that uses a
flexible diskette made of thin plastic encased in a protective casing .The Floppy Disk
itself enable the information to be transported from one computer to another very easily
Two types of Floppy
5 ¼ 40 tracks 360 KB /1.2 MB
3 ¼ 80 Tracks 720/1.44 MB
57
Hard Disk
Date invented December 14, 1954
Invented by An IBM team led by Rey Johnson
Connects to Host adapter of system, in PCs typically integrated into
motherboard. Via one of:
PATA (IDE) interface
SATA interface
SAS interface
SCSI interface (popular on servers)
FC interface (almost exclusively found on servers)
USB interface
Market Segments Desktop computers
Mobile computing
Enterprise computing
Consumer electronic
A hard disk drive (often shortened as hard disk, hard drive, or HDD) is a non-volatile
storage device that stores digitally encoded data on rapidly rotating platters with magnetic
surfaces. Strictly speaking, "drive" refers to the motorized mechanical aspect that is
distinct from its medium, such as a tape drive and its tape, or a floppy disk drive and its
floppy disk. Early HDDs had removable media; however, an HDD today is typically a
sealed unit (except for a filtered vent hole to equalize air pressure) with fixed media
HDDs (introduced in 1956 as data storage for an IBM accounting computer) were
originally developed for use with general purpose computers. During the 1990s, the need
for large-scale, reliable storage, independent of a particular device, led to the introduction
of embedded systems such as RAIDs, network attached storage (NAS) systems, and
storage area network (SAN) systems that provide efficient and reliable access to large
volumes of data. In the 21st century, HDD usage expanded into consumer applications
such as camcorders, cellophanes (e.g. the Nokia N91), digital audio players, digital video
players, digital video recorders, personal digital assistants and video game consoles.
58
Technology
HDD record data by magnetizing ferromagnetic material directionally, to represent either
a 0 or a 1 binary digit. They read the data back by detecting the magnetization of the
material. A typical HDD design consists of a spindle that holds one or more flat circular
disks called platters, onto which the data is recorded. The platters are made from a nonmagnetic
material, usually aluminum alloy or glass, and are coated with a thin layer of
magnetic material, typically 10-20 nm in thickness with an outer layer of carbon for
protection. Older disks used iron (III) oxide as the magnetic material, but current disks
use a cobalt-based alloy
The platters are spun at very high speeds. Information is written to a platter as it rotates
past devices called read-and-write heads that operate very close (tens of nanometers in
new drives) over the magnetic surface. The read-and-write head is used to detect and
modify the magnetization of the material immediately under it. There is one head for
each magnetic platter surface on the spindle, mounted on a common arm. An actuator
arm (or access arm) moves the heads on an arc (roughly radially) across the platters as
they spin, allowing each head to access almost the entire surface of the platter as it spins.
The arm is moved using a voice coil actuator or in some older designs a stepper motor.
The magnetic surface of each platter is conceptually divided into many small submicrometer-
sized magnetic regions, each of which is used to encode a single binary unit
of information. Initially the regions were oriented horizontally, but beginning about 2005,
the orientation was changed to perpendicular. Due to the polycrystalline nature of the
magnetic material each of these magnetic regions is composed of a few hundred magnetic
grains. Magnetic grains are typically 10 nm in size and each form a single magnetic
domain. Each magnetic region in total forms a magnetic dipole which generates a highly
localized magnetic field nearby.
59
A write head magnetizes a region by generating a strong local magnetic field. Early
HDDs used an electromagnet both to magnetize the region and to then read its magnetic
field by using electromagnetic induction.
Later versions of inductive heads included metal in Gap (MIG) heads and thin film heads.
As data density increased, read heads using magneto resistance (MR) came into use; the
electrical resistance of the head changed according to the strength of the magnetism from
the platter. Later development made use of spintronics; in these heads, the magneto
resistive effect was much greater than in earlier types, and was dubbed "giant" magneto
resistance (GMR). In today's heads, the read and write elements are separate, but in close
proximity, on the head portion of an actuator arm. The read element is typically magnetoresistive
while the write element is typically thin-film inductive
HD heads are kept from contacting the platter surface by the air that is extremely close to
the platter; that air moves at, or close to, the platter speed .The record and playback head
are mounted on a block called a slider, and the surface next to the platter is shaped to
keep it just barely out of contact. It's a type of air bearing.
In modern drives, the small size of the magnetic regions creates the danger that their
magnetic state might be lost because of thermal effects. To counter this, the platters are
coated with two parallel magnetic layers, separated by a 3-atom-thick layer of the nonmagnetic
element ruthenium, and the two layers are magnetized in opposite orientation,
thus reinforcing each other. Another technology used to overcome thermal effects to
allow greater recording densities is perpendicular recording, first shipped in 2005, as of
2007 the technology was used in many HDDs.
The grain boundaries turn out to be very important in HDD design. The reason is that, the
grains are very small and close to each other, so the coupling between adjacent grains is
very strong. When one grain is magnetized, the adjacent grains tend to be aligned parallel
to it or demagnetized. Then both the stability of the data and signal-to-noise ratio will be
sabotaged. A clear grain boundary can weaken the coupling of the grains and
subsequently increase the signal-to-noise ratio. In longitudinal recording, the singledomain
grains have uneasily anisotropy with easy axes lying in the film plane. The
consequence of this arrangement is that adjacent magnets repel each other. Therefore the
magneto static energy is so large that it is difficult to increase a real density.
Perpendicular recording media, on the other hand, has the easy axis of the grains oriented
perpendicular to the disk plane. Adjacent magnets attract to each other and magneto static
energy are much lower. So, much higher a real density can be achieved in perpendicular
recording. Another unique feature in perpendicular recording is that a soft magnetic
under layer are incorporated into the recording disk. This under layer is used to conduct
writing magnetic flux so that the writing is more efficient. This will be discussed in
writing process. Therefore, a higher anisotropy medium film, such as L10-FePt and rareearth
magnets, can be used.
60
ATA Hard Drive
SATA Hard Drive
61
SCSI Hard Drive
Floppy Disk
Date invented 1969(8-inch),
1976(5¼-inch),
1982 (3½-inch)
Invented by IBM team led by David L. Noble
Connects to Controller via: cable
A Floppy disk is a data storage medium that is composed of a disk of thin, flexible
("floppy") magnetic storage medium encased in a square or rectangular plastic shell.
Floppy disks are read and written by a floppy disk drive or FDD, the initials of which
should not be confused with "fixed disk drive," which is another term for a (non
removable) type of hard disk drive.
62
Invented by IBM, floppy disks in 8-inch (200 mm), 5¼-inch (133.35 mm), and 3½-inch
(90 mm) formats enjoyed many years as a popular and ubiquitous form of data storage
and exchange, from the mid-1970s to the late 1990s. While floppy disk drives still have
some limited uses, especially with legacy industrial computer equipment,[2] they have
now been largely superseded by USB flash drives, external hard drives, CDs, DVDs, and
memory cards (such as Secure Digital).
Before hard disks became affordable, floppy disks were often also used to store a
computer's operating system (OS), in addition to application software and data. Most
home computers had a primary OS (and often BASIC) stored permanently in on-board
ROM, with the option of loading a more advanced disk operating system from a floppy,
whether it be a proprietary system, CP/M, or later, DOS.
The 5¼-inch 1.2 MB floppy disk drive
The 3½-inch 2.88 MB floppy disk drive
63
CD-ROM
Media type Optical Disc
Capacity 184 MB (8 cm)
650-900 MB (12 cm)
Read mechanism 150 KB/s (1×)
10800 KB/s (72x)
Write mechanism 150 KB/s (1×)
8400 KB/s (56x)
Usage Data storage, video, audio, open internet
CD-ROM (pronounced an initialize of "compact disc read-only memory") is a prepressed
compact disc that contains data accessible to, but not writable by, a computer for
data storage and music playback, the 1985 “Yellow Book” standard developed by Sony
and Philips adapted the format to hold any form of binary data
CD-ROMs are popularly used to distribute computer software, including games and
multimedia applications, though any data can be stored (up to the capacity limit of a
disc). Some CDs hold both computer data and audio with the latter capable of being
played on a CD player, while data (such as software or digital video) is only usable on a
computer (such as ISO 9660 format PC CD-ROMs). These are called enhanced CDs.
Although many people use lowercase letters in this acronym, proper presentation is in all
capital letters with a hyphen between CD and ROM. It was also suggested by some,
especially soon after the technology was first released, that CD-ROM was an acronym for
"Compact Disc read-only-media", or that it was a more "correct" definition. This was not
the intention of the original team who developed the CD-ROM, and common acceptance
of the "memory" definition is now almost universal. This is probably in no small part due
to the widespread use of other "ROM" acronyms such as Flash-ROMs and EEPROMs
where "memory" is usually the correct term.
64
Data Transfer Speeds
Transfer Speed KB/s Mb/s
1x 150 1.2288
2x 300 2.4576
4x 600 4.9152
8x 1200 9.8304
10x 1500 12.2880
12x 1800 14.7456
20x 3000 24.5760
32x 4800 39.3216
36x 5400 44.2368
40x 6000 49.1520
48x 7200 58.9824
50x 7500 61.4400
52x 7800 63.8976
56x 8400 68.8128
72x 10800 88.4736
Blu-ray Disc
Media type High-density optical disc
Encoding MPEG-2, H.264/MPEG-4 AVC, and VC-1
Capacity 25 GB (single-layer)
50 GB(dual-layer)
1 TB to 5TB (future)
Block size 64kb ECC
Read mechanism 405nmlaser:
1×at36Mbit/s(4.5MByte/s)
2×at72Mbit/s(9MByte/s)
4×at144Mbit/s(18MByte/s)
6×at216Mbit/s[1](27MByte/s)
8×at288Mbit/s(36MByte/s)
12× at 432 Mb/s (54 MB/s)
65
Usage Data storage
High-definition video
High-definition audio
PlayStation 3
games
possibility of Quad HD 2160p
Blu-ray Disc (also known as Blu-ray or BD) is an optical disc storage medium designed
to supersede the standard DVD format. Its main uses are for storing high-definition
video, PlayStation 3 games, and other data, with up to 25 GB per single layered, and 50
GB per dual layered disc. The disc has the same physical dimensions as standard DVDs
and CDs. The name Blu-ray Disc derives from the blue-violet laser used to read the disc.
While a standard DVD uses a 650 nanometer red laser, Blu-ray uses a shorter
wavelength, a 405 nm blue-violet laser, and allows for almost six times more data storage
than a DVD. During the format war over high-definition optical discs, Blu-ray competed
with the HD DVD format. Toshiba, the main company supporting HD DVD, ceded in
February 2008, and the format war ended;[2] in July 2009, Toshiba announced plans to
put out its own Blu-ray Disc device by the end of 2009. Blu-ray Disc was developed by
the Blu-ray Disc Association, a group representing makers of consumer electronics,
computer hardware, and motion pictures
Data rate Write time for Blu-ray Disc (minutes)
Drive speed
Mb/s MB/s Single-Layer Dual-Layer
1× 36 4.5 90 180
2× 72 9 45 90
4× 144 18 23 45
6× 216 27 15 30
8× 288 36 12 23
66
12×* 432 54 8 15
SCSI
Small Computer System Interface or SCSI (pronounced scuzzy), is a set of standards
for physically connecting and transferring data between computers and peripheral
devices. The SCSI standards define commands, protocols, and electrical and optical
interfaces. SCSI is most commonly used for hard disks and tape drives, but it can connect
a wide range of other devices, including scanners and CD drives. The SCSI standard
defines command sets for specific peripheral device types; the presence of "unknown" as
one of these types means that in theory it can be used as an interface to almost any
device, but the standard is highly pragmatic and addressed toward commercial
requirements. SCSI is an intelligent, peripheral, buffered, peer to peer interface. It hides
the complexity of physical format. Every device attaches to the SCSI bus in a similar
manner. Up to 8 or 16 devices can be attached to a single bus.
There can be any number of hosts and peripheral devices but there should be at
least one host. SCSI uses hand shake signals between devices, SCSI-1, SCSI-2 have the
option of parity error checking. Starting with SCSI-U160 (part of SCSI-3) all commands
and data are error checked by a CRC32 checksum. The SCSI protocol defines
communication from host to host, host to a peripheral device, and peripheral device to a
peripheral device. However most peripheral devices are exclusively SCSI targets,
incapable of acting as SCSI initiators--unable to initiate SCSI transactions themselves.
Therefore peripheral-to-peripheral communications are uncommon, but possible in most
SCSI applications. The Symbiosis Logic 53C810 chip is an example of a PCI host
interface that can act as a SCSI target
SCSI interfaces
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SCSI Hard Drive
Tape Drive
A tape drive, which is also known as a streamer, is a data storage device that reads and
writes data stored on a magnetic tape. It is typically used for archival storage of data
stored on hard drives. Tape media generally has a favorable unit cost and long archival
stability. Instead of allowing random-access to data as hard disk drives do, tape drives
only allow for sequential-access of data. A hard disk drive can move its read/write heads
to any random part of the disk platters in a very short amount of time, but a tape drive
must spend a considerable amount of time winding tape between reels to read any one
particular piece of data. As a result, tape drives have very slow average seek times.
Despite the slow seek time, tape drives can stream data to tape very quickly. For
example, modern LTO drives can reach continuous data transfer rates of up to 80 MB/s,
which is as fast as most 10,000 rpm hard disks.
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DVD Recordable
DVD-R is a DVD recordable format. A DVD-R type has a storage capacity of 4.71 GB
(or 4.38 GB), although the capacity of the original standard developed by Pioneer was
3.95 GB (3.68 GB). Both values are significantly larger than the storage capacity of its
optical predecessor, the 700 MB CD-R – a DVD-R has 6.4 times the capacity of a CD-R.
Pioneer has also developed an 8.54 GB dual layer version, DVD-R DL, which appeared
on the market in 2005.Data on a DVD-R cannot be changed, whereas a DVD-RW (DVDrewritable)
can be rewritten multiple (1000+) times. DVD-R (W) is one of three
competing industry standard DVD recordable formats; the others are DVD+R(W) and
DVD-RAM.
ATA DVD Writer
SATA Connector on DVD Writer/Rom
Chapter – 5
System Buses
69
It is communicating port between MPU and peripheral. It is nothing but groups of wire
which carry bits.
Three types of bus
Address Bus: - It is groups of 16 lines. The address bus is unidirectional that means data
flow in one directions that is MPU to peripheral .MPU uses the address but to identity the
peripheral and memory location.
Data Bus: - It is groups of 8 lines used for the flow of Data bi-directional that means data
flow from peripheral to MPU and MPU to peripheral. MPU used data bus to travel data.
Control Bus: - Control Bus is signal lines MPU uses this line to provide control signal to
peripheral.
CPU (Central Processing Unit)
A Central Processing Unit (CPU) or processor is an electronic circuit that can execute
computer programs, which are actually sets of instructions. This term has been in use in
the computer industry at least since the early 1960s. The form, design and
implementation of CPUs have changed dramatically since the earliest examples, but their
fundamental operation remains much the same.
The “Brain” of any computer is the central processing unit (CPU). This component does
all the calculations and performs 90 percent of all the functions of a computer
Receive and store data in to main storage memory
Control sequence of Operations
Give commands to all parts of the computer system.
Carry out processing and to output the result
Early CPUs were custom-designed as a part of a larger, sometimes one-of-a-kind, and
computer. However, this costly method of designing custom CPUs for a particular
application has largely given way to the development of mass-produced processors that
are made for one or many purposes. This standardization trend generally began in the era
of discrete transistor mainframes and minicomputers and has rapidly accelerated with the
popularization of the integrated circuit (IC).
The IC has allowed increasingly complex CPUs to be designed and manufactured to
tolerances on the order of nanometers.
70
Both the miniaturization and standardization of CPUs have increased the presence of
these digital devices in modern life far beyond the limited application of dedicated
computing machines. Modern microprocessors appear in everything from automobiles to
cell phones and children's toys.
CPU Unit
Arithmetic and Logic Unit
Control Unit
Memory Storage Unit
ALU: - The ALU is a section where all the arithmetic and logic functions are carried out.
We know that every arithmetic operation requires two operations. The operation then
produces a result.
Control Unit: - The CPU directs all operations in side the computer it is known as nerve
center of the computer. It gives command to transfer data from the input device to the
memory of arithmetic and logic unit. It also transfers the result from ALU to the memory
and on to the output device for printing.
Memory Unit: - Immediate access storage (IAS) which is a part of Central Processing
Unit it self.
(AMS) Auxiliary Memory Storage or backing storage which is external to central
processing unit.
Memory stores instructions waiting to be obeyed by other components of the CPU.
Socket/Slot Processors
Socket 4:-Pentium 60/66, Pentium 60/66 Over Drive
Socket 5: -Pentium 75-133, Pentium 75+ Overdrives, and AMD K5
Socket 6:- 486DX4, 486 Pentium Over Drive
Socket 7:- Pentium 75-200, Pentium 75+ Over Drive, Pentium MMX, AMD
K6
Super Socket 7:-AMD K6-2, K6-III
Socket 8:-Pentium Pro
Slot 1:-Pentium II, Pentium III, Celeron, and all SECC and SECC2
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Slot 2:-Pentium II Xeon, Pentium III Xeon
Slot A: - Early AMD Athlon
Socket 370:- PPGA processors, including Pentium III and Celeron
Socket 423:-Early Pentium 4
Socket A :-( Socket 462) AMD Athlon, Athlon XP, Athlon XP-M, Athlon
MP, Thunderbird, Duron, Sempron
Socket 478:-Pentium 4, Pentium 4 Extreme Editions, and Celeron
Socket 479:-Pentium M, Celeron M
Socket 486:-80486
Socket 563:-AMD low-power mobile Athlon XP-M
Socket 603:-Intel Xeon
Socket 604:-Intel Xeon with Micro FCPGA package
Socket 754:-Athlon 64, Sempron, and Turion 64
Socket 771:-Xeon 50x0 Dual-cores
Socket T :-( LGA 775) Pentium 4, Pentium D dual-core, Celeron D, Pentium
Extreme Edition
Socket 939:-Athlon 64, Athlon 64 FX, and Athlon 64 X2, Opteron 100-series
Socket/Slot Processors
Socket 940:-Athlon 64 FX (FX-51), Opteron
Socket F :-( Socket 1207) Replaces Socket 940 when used with Opteron
multiprocessor Systems)
Socket AM2:- AMD single-processor systems, replaces Socket 754 and
Socket 939
Socket S1:-AMD-based mobile platforms, replaces Socket 754 in the mobile
sector
PAC418:-Itanium
PAC611:- Itanium 2
Some Range of C.P.U
8085
Launched by: - 1978
Data Bus: - 8 bit
Address Bus: - 20 bit
Ram: - 1mb
72
Speed: - 4.7 MHz
8088
Launched by: - 1979
Data Bus: - 8 bit
Address Bus: - 20 bit
Ram: - 1Mb
Speed: - 8 MHz
80186
Launched by: - 1990
Data Bus: - 16 bit
Address Bus: - 20 bit
Ram: - 1Mb
Speed: - 8 MHz
80286
Launched by: - 1982
Data Bus: - 16 bit
Address Bus: - 24 bit
Ram: - 16 mob, 8 Mb
Speed: - 8, 10, 12.5 MHz
80386
Launched by: - 1985
Data Bus: - 32bit
Address Bus: - 32 bit
Ram: - 16 Mb
Speed: - 16 to 33 MHz
80486
Launched by: - 1989
Data Bus: - 32 bit
Address Bus: - 32 bit
Ram: - 16 to 32 Mb
Speed: - 33 MHz
80586
Launched by: - 1991
Data Bus: - 32 bit
Address Bus: - 32 bit
Ram: - 16 Mb
Speed: - 66 MHz
Pentium1
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Launched by: - 1993
Data Bus: - 64 bit
Address Bus: - 32 bit
Ram: - 32 Mb
Speed: - 60 to 200 MHz
Pentium Pro
Launched by: - 1995
Data Bus: - 64 bit
Address Bus: - 32 bit
Ram: - 32, 64 Mb
Speed: - 150 to 200 MHz
Socket: - 8
Voltage: - 2.5v
Cache memory: - 32kb
Pentium2
Launched by: - 1997
Data Bus: - 64 bit
Address Bus: - 32 bit
Ram: - 32, 64, 128 Mb
Speed: - 233 to 450 MHz
Socket: - (SECC) single Edge Contact Cartage
Voltage: - 3.3v
Cache memory: - 32kb
Slot: - I, II
Celeron (P3)
Launched by: - 1999
Data Bus: - 64 bit
Address Bus: - 32 bit
Ram: - 32, 64, 256 Mb
Speed: - 400 to 600 MHz
P III
Launched by: - 1999
Data Bus: - 64 bit
Address Bus: - 32 bit
Ram: - 64, 128, 256 Mb
Speed: - 450 to 1000 MHz
Slot: - SECC (single edge contact cartage)
Socket: - 370
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Voltage: - 3.3v
Cache memory: - 32kb
P IV
Launched by: - 2003
Data Bus: - 64bit
Address Bus: - 64bit
Ram: - 128, 256, 512, 2 GB, 2 GB
Speed: - 1.4 GHz to 3.06 GHz
Socket: - 427, 478, LGA 775
Voltage: - 1.3v to 1.7v
Cache memory: - Up to 512 kb
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Chapter - 6
Monitor
Monitor is an output device, which is used to obtain a soft copy of the image.
Basic terms of display
Pixel:- Pixel is the smallest dot, which can be, represent on the screen
Resolution:-It’s the total number of pixel present on the screen (width by height).
Resolution:-
Monitor type Height Width
Color graphics Adapter (CGA) 320 pixels 200 pixels
Enhanced graphics Adapter (EGA) 640 pixels 350 pixels
Video graphics Array (VGA) 640 pixels 480 pixels
Super VGA (SVGA) 800 pixel 600 pixels
1024 pixels 768 pixels
Triad:- Triad is the combination of the three primary color, which form the final color
(Red, Green, and Blue).
Horizontal Scanning: - It is process of drawing Horizontal line on the Screen.
Vertical Scanning:- It is the process of shifting to the line Vertical Scanning
Raster: - It is the continuous Horizontal and Vertical Scanning.
Retrace:- It is the beginning of the Image formation from the first Horizontal line after
the data is sent again
Convergence:- It’s the process, which through which the different color of the electron
beams combined, at the convergence point on the shadow mask to produced the final
color.
Inside CRT Displays
If we open a CRT display we can find following circuit:
Video Drive Circuit
Vertical Drive Circuit
Horizontal Drive Circuit
Power Supply Circuit
The video signal is amplified by a simple transistor switch (Video drive circuit) that
drives the CRT video-control grid. A contrast control affects the separation between light
and darkness by adjusting the amount of amplification given to the video signal.
The vertical drive circuit controls the up-down position of the electron beam. A vertical
sweep oscillator (54 to 72 Hz depending on the monitor type) provides a ramping signal
that resembles a saw tooth wave. The vertical ramp is triggered by the presence of a
vertical sync transistor circuit that connects directly to the vertical deflection coil (or
yoke) fixed to the neck of the CRT.
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Diagram of Monochrome CRT
The magnetic field produced by the vertical ramp signal maneuvers the electron beam. As
the ramp starts from 0 and increases in amplitude, the beam moves down the screen.
The horizontal drive circuit controls the left-right position of the electron beam. A
horizontal oscillator (15.85 to 38 kHz depending on the monitor type) provides a short
square-wave pulse
The horizontal pulse is triggered by the presence of a horizontal sync pulse .
This horizontal pulse signal is amplified by an output driver transistor circuit that
connects directly to the horizontal deflection yoke fixed to the neck of the CRT.
As with the vertical system, the magnetic field produced by the horizontal signal
maneuvers the electron beam.
That high voltage is produced by a device known as an FBT (fly back Transformer). The
FBT “spikes” a relatively low voltage up to a much higher level.
A high-voltage pulse is developed during the horizontal retrace (the brief time when the
beam has finished drawing one line and is turned off to be repositioned for the next line).
The primary winding in the fly back transformer is coupled to the horizontal output.
When the horizontal signal drops to 0, it does so almost instantly that drives transformer
output to a very high level.
Fly back voltages can be from 15,000 to 30,000 Vdc.
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Chapter - 7
Printers
Objective
Printers
Daisy wheel printer
Chain printer
Drum printers
Dot-matrix printers
Inkjet printers
Laser jet printers
Printers
Printers are output devices used with the computer. Printer is used to get a “Hard
Copy” of the results, to get permanent output on the paper or some other medium
such as the overhead projector (OHP) film etc.
Today, printers are capable of high-quality monochrome i.e. single color and
multi-color printout at a very high speed. Most of the printer can also produce
graphic i.e. images other than plain text on the paper.
Printers are often categorized based on the mechanism used by the printer to
print the image and also they can be categorized based on the image formation
method used by them.
Types of the printers based on the image formation method are:
Fully Formed Character printer and
Bit Image printer
Types of the printers based on the printing mechanism are:
Impact and
Non-impact printers
Image Formation Method
Different printers use different method to produce the required output on the
paper or any other output media such as the OHP transparencies etc.
The quality of the output and different capabilities of the printer such as being
able to print graphic image, depends on the method used to generate the image by
the printer.
Two possible image formation methods are FULLY FORMED CHARACTER
printer and BIT IMAGE printer.
Fully Formed Character Printers
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Typewriter is a very good example of the fully formed character type printing.
Just like the typewriter, in a fully formed character type of printer, all the
printable characters are mad in advance and provided in the printer, as a part of
printer hardware itself.
Almost all the fully formed character type printer use impact method to print on
the paper. In this method first a hammer strikes the required character shape, this
makes the character shape to press some kind if inked ribbon against the paper,
this will produce the required shape on the paper.
Most of the time the hammer is powered by a solenoid, which is controlled by the
electronics of the printer and the computer.
One positive thing about this printing technology is, it produces very good-quality
output Negative points are, one can not use these printers to print graphics image,
most of these printers generate high noise because of their impact mechanism
and these printers have a very limited character styles available.
Some common fully formed character type printers are
Daisy-Wheel printer
Chain printer
Drum printer
Bit-Image Printers
In this method printer does not contain any specific character shape, instead it
prints the required character shape using a matrix of dots.
These dots are arranged to resemble the character or shape that you want to print.
In most of these printers, characters are formed from dots placed within a
matrix this is the reason these printers would be “bit-image printers”.
The bit-image printers are most popular printers today and the reason is a bitimage
printer is a very versatile printer, it can be used to print text as well as
graphic images.
By controlling individuals’ dots, computer can make these printers to produce any
required pattern.
If one is using a Dot-Matrix printer, then just by sending instruction to the
printer one can change, the character style, the height of the character or even
the width of the character, anytime during the printing, without changing any
hardware.
The speed and the image quality produced by the bit-image printer depend very
much on the technology used to generate these images.
At the lower end is an ordinary Dot Matrix printer, which provides output that
looks like ordinary computer printed output, whereas at the higher end a Laser
printer can give output look like pages of this printed book.
Printing Mechanism
79
One can also divide printers into two categories, Impact and Non-impact based on
their printing mechanism.
Printing mechanism refers to the method used by the printer to produce the image
on the output media, such as paper, OHP transparency etc.
Impact Printers
Impact printers; actually use impact to create an image on the output media.
All impact printers smash a hammer of some kind against an inked ribbon onto
the paper; this makes impact mark to appear on the paper.
Some common impact type printers are:
o Daisy-Wheel Printer
o Dot-Matrix Printer
o Chain Printer
o Drum Printer
A Dot-Matrix printer is an impact type printer, which works on bit-image
technology.
This printer creates image on the output media, by first forming the required
shape using a matrix of dots and then striking the media through inked ribbon.
These printers are very low-priced and economical to operate compared to the
printers using other technologies.
Advantage
Impact printer’s design and functions are relatively straightforward and easy to
understand compared to a non-impact printer.
As these printers generate image by striking the output media, most impact
printers can output media, most impact printers can output on any media, where
the ink can be used to print and media can be fed into the printer.
Another very major advantage of the impact printers is that they can used to print
on multipart forms.
As the Impact printers strike the media to create an impression, they can print not
just through a ribbon but also through several sheets of paper and carbon paper to
print multiple carbon copies in a single pass.
For a number of business applications where exact carbon copies are required,
impact printers are the only available option.
Disadvantage
The main advantage of the impact printer is also its main disadvantage, the
hammer striking against the ribbon and paper which allows multiple copies to be
made also generates noise.
Non-Impact Printer
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Non-Impact printers do not strike any ribbon or paper to produce the image,
instead they use ink spraying, electrostatic magnetization or heat process to
produce the required image on the image or any other output media.
The common non-impact technologies are :
Inkjet
Laser
Soundless operation and very high quality output of these printers are making
them very popular.
At the lower price end Inkjet printers are replacing Dot-Matrix printers and at the
higher end Laser printer is slowly becoming one of the most common printer.
One disadvantage with these printers is they cannot be used to print carbon copies
or multiples copies in a single pass, which requires some kind of impact to be
applied.
Daisy Wheel Printer
Daisy-Wheel (or Petal-Wheels) was one of the first impact type printers used with the
computer. They were initially used with dedicated word processors, because of their
very high quality output. These are fully formed character type of printers, all the
characters that these printers are capable of printing, are made available with the
printer on a wheel like structure. The name Daisy Wheel is given to these printers
because of the daisy flower like shape of the character wheel used on these printers.
These wheels are made of high-impact durable plastic or metal. Each spoke or the
petal of the Daisy Wheel contains one letter or symbol. When a character is to be
printed the wheel spins on its center to bring that character at the correct printing
position under the small hammer. Once the character reaches correct position, it is
struck by the hammer activated by a solenoid. This makes the character on the petal
to press through an inked ribbon and strike the paper, leaving an image of the
character on the paper. One can change these wheels to print different type of
characters, as these wheels are available in a wide range of letter styles and sizes.
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Chain Printer
Chain printer is another example of the fully formed character type printers. The name
chain printer is used for these printers because on these printers all the printable
characters are attached to a chain like structure. When ever a character is to be printed
The chain rotates in a circular fashion until the required character reaches correct
position. When the character to be printed reaches correct position a hammer strikes the
character to the inked position and Through the ribbon character’s image gets printed on
the paper. These printers provide very high-speed output and are mainly used in the high
volume works such as printing of electricity bill, telephone bills etc. On a normal size
computer stationary page of 132 characters per line, these printers print at the speed of
about 15 to 30 pages per minute (PPM).
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Drum Printers
Drum printers are another variation of the fully formed character type impact printers.
When a character is to be printed at a particular position The drum is rotated until the
desired character comes at the correct position. Next, a hammer strikes the paper
against the inked ribbon and the character on the drum, making the character’s image
to appear on the paper. Printer allows the entire line to be printed at a time, which give it
the name of “Line printer”. These printers provide very high-speed output and are mainly
used in high volume works such as printing of electricity bill, telephone bills, pay slips of
big corporations etc On a normal size computer stationary page of 132 characters per
line, these printers provide about 15 to 30 page per minute (PPM) output. These printers
achieve this high speed by printing all the letters of the line at one rotation of the drum, as
the drum rotates different letters of the line gets printed and in one rotation of the drum
all the letters of the line gets printed. For example of you want to print “DIFFERENT
LETTERS” First all the letters “A” in the line will get printed, next all the “B”, then all
the “C” and so on until all the letters of the line is printed, so, our example will be printed
in the following fashion The high-speed rotation and printing gives a distinctive uneven
look to the output produced by the drum printers.
D E E E E
D FFE E E E
DIFFE E E E
DIFFE E LE E
DIFFE EN LE E
DIFFEREN LE ER
DIFFEREN LE ERS
DIFFERENT LETTERS
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Dot-Matrix Printers
Dot-Matrix printers are bit image impact type of printers. These printers form characters
and images by placing pattern of dots on the paper by striking inked ribbon with a
number of small pins. These printers use a print head that shuttles back and forth across
the width of the paper and a number of thin print wires on the head act as hammers that
strike the ribbon and squeeze ink from ribbon to paper. Most Dot-Matrix printer models
are inexpensive, small, lightweight and very efficient at their job. As these are impact
type of printer’s one main drawback of these printers is the noise generated by them, but
compared to fully formed character type impact printers such as the Daisy-Wheel printer,
these printers are less noisy. Dot-Matrix printers have one real advantage over all the
other kinds of printers. Another advantage of these printers is they are very versatile, as
they generate character or image using combination of dots i.e. these printers can be used
to produce graphs, charts and ven pictures under the computer’s control. The per page
printing cost of Dot-Matrix printers are very-very low, because the only consumable
required for the printing is the printer ribbon which can be re-inked or refilled at a very
cheap price. Dot-Matrix printers print ant text character by character, so the speed of
these printers is expresses in Characters Per Second or more commonly CPS. Common
printing speed ranges from 50 CPS to 500 CPS, i.e. a normal page could be printed at the
speed of one quarter to 6 pages per minute (PPM). If we consider 1 CPS to be about 10-
12 Words Per Minute (WPM), in typing terms, this speed is in a range of about 600 to
6000 WPM. Many of the Dot-Matrix printers offer color-printing option, either using a
single multicolor ribbon or using complex multiple color ribbons.
To speed up the printing operation, most of the Dot-Matrix printers print bi-directionally,
i.e. they print one row from left to right and then the next row from right to left. This
mode of operation saves the time that would be wasted for print head to return to the left
side of the page to start the next line. The Dot-Matrix printers available in the market can
be broken down into three different segments based on their capability. The extremely
high-volume models useful for large heavy duty work such as electricity or telephone
bill printing, used by the big corporations, banks etc. The cost of these printers can be
very high .The high-volume models which are useful for people running small job works
or for small business whose output requirements are higher than normal. The personal
models useful for small business, office, home users, sell for Rs.7000 to 10,000.
The Dot-Matrix printer available in the market can also be classified according to the
number of pins used in their print head. The 9 pin print head is most common and lowcost
printers but their print quality is very poor. These printers have ninepins in a
single vertical column. The 24 pin print head is highest quality Dot-Matrix printers.
These printers provide very high quality print. The 24-pin heads usually have three offset
columns of eight pins each.
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Color Dot-Matrix Printers
Initially color Dot-Matrix printing required a separate printer, but now most of the Dot-
Matrix printer has option to add color kit and color ribbon to convert a normal single
color printer into color printer. The four-color ribbons of black, yellow, red and blue
bands allow the printer to produce up to seven different colors. These ribbons cost two to
three times more than the normal black ribbons. So, if you use color only occasionally,
it’s good idea to use a black ribbon for normal printing and swap it for four-color ribbon
only when you need the color. To prevent the ribbon from drying out, you can store them
in a plastic bag when not in use. Color Dot-Matrix printer can be used to print business
graphs and charts as well as to produce hard-copy of presentation materials such as charts
with clip-arts etc., it can also be used to create colorful OHPs. Another valuable use for
color Dot-Matrix printer is in the creation of drafts of output that will later be generated
by a color page printer. As the cost of color page printers have dropped, their initial cost
and printing cost are still significantly higher than a color Dot-Matrix printer. A color
Dot-Matrix printer should be capable of producing high quality color printout with deep,
saturated colors with little or no white showing through. Printing in multiple colors with a
Dot-Matrix printer could be very slow process, as most of the time the print head has to
make more than one pass to blend different colors.
.
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Inkjet Printers
Inkjet printers occupy a position between Dot-Matrix printers and the Laser printers.
These are small printers that provide the resolution of the Laser printers at accost i.e.
close to the Dot-Matrix printer. But, per page printing cost of the Inkjet printer is much
higher than the Dot-Matrix printers; it is even higher than that of laser printers. These
printers are perfect compromise of cost, speed and quality. Only with the close inspection
one can detect the difference between Laser printer output and the Inkjet output. Another
quality of the Inkjet is these printers print very silently; one does not hear the noise
associated with the Dot-Matrix printers. Inkjet uses bit image formation method.
Character shape is printed using matrix of dots. Instructions given to printer can change
the character style, height of character without any change in hardware. Inkjet is a nonimpact
printer i.e. produces image by ink spraying, Electrostatic magnetization or heat
process. Print operation is soundless. Inkjet cannot be used to print carbon copies or
multiple copies in a single pass. Inkjet sprays the ink from tiny nozzles of the printer
cartridge onto the paper to place pattern of dots on paper to generate image. Output
quality of Inkjet printer look similar to the Laser printer. Inkjet uses piezo-electric crystal
or a resistor to force the ink out of the nozzle of the ink cartridge. There are two types of
inkjet technologies
Piezo-Electric Technology
Bubble Technology
Piezo-Electric Technology
Piezo-electric crystals bend or expand when electric charge is applied to the crystal; this
forces the minute quantity of ink out of the nozzle on to the paper. A sharp digital pulse
of electricity cause piezo-electric crystal to switch & force ink through the nozzle onto
the paper
Bubble Technology
A resistor heats creating small air bubble, to force ink out through the nozzle.
A small electric current is passed through the bottom of chamber, which heats the ink for
a fraction of second at a temperature of 300°C. This temperature boils the ink and forms
a bubble, and bubble in turn pushes a tiny amount of ink through the nozzle on to the
paper. The bubble then cools off and collapses creating a suction that pulls fresh ink into
the chamber. The Jet of the inkjet printer can be of two types -Pulsing Jet, Continuous
stream Jet
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Color Inkjet
The color inkjet produce very good quality color images, there are two main reason for
this, first is the Inkjet printer sprays the ink directly onto the paper there is no ribbon in
between to dull the image being printed, and the second reason is the Inkjet’s ink remain
fluid enough even after they have been sprayed on the paper to blend together.
This gives color Inkjet printers the capability to mix their primary colors together to
create intermediary tones. A full-color Inkjet printer needs at least four print heads,
one for each primary color (yellow, magenta yan) and one for black. Some printers
provide all this three primary colors in a single print head also some printers do not
provide the black color print head at all and Produce black color by mixing the three
primary colors, but this will not give good, saturated, dark black color, instead you get a
washed out black color.
A typical character is formed by the drops.
As the resistor cools, the bubble collapses and the resulting suction pulls fresh ink from
the attached reservoir into the ink chamber. For color printing multiple cartridge of three
basic colors - Cyan, Magenta and Yellow are used. Color output of Inkjet printer is very
high quality, as ink is directly deposited on the paper. Most of good quality Inkjet printers
provide additional block cartridge other than three basic color cartridges. Mixing of three
basic colors to produce black gives very faded black color. Some Inkjet printers use
piezo-electric crystal to force the ink out of the chamber.
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Laser Printer
Electro photographic (EP) Print Process
The EP print process is the process by which an EP laser printer forms images on paper.
It consists of six major steps, each for a specific goal. Although many different
manufacturers call these steps different things or place them in a different order, the basic
process is still the same.
Here are the steps in the order you will see them on the exam:
1. Cleaning
2. Charging
3. Writing
4. Developing
5. Transferring
6. Fusing
Before any of these steps can begin, however, the controller must sense that the printer is
Ready to start printing (toner cartridge installed, fuser warmed to temperature, and all
covers in place). Printing cannot take place until the printer is in its ready state, usually
indicated by an illuminated Ready LED light or a display that says something like 00
READY (on HP printers).
STEP 1: CLEANING
In the first part of the laser print process, a rubber blade inside the EP cartridge scrapes
any toner left on the drum into a used toner receptacle inside the EP cartridge, and a
fluorescent lamp discharges any remaining charge on the photosensitive drum (remember
that the drum, being photosensitive, loses its charge when exposed to light). This step is
called the cleaning step The EP cartridge is constantly cleaning the drum. It may take
more than one rotation of the photosensitive drum to make an image on the paper. The
cleaning step keeps the drum fresh for each use. If you didn’t clean the drum, you would
see ghosts of previous pages printed along with your image.
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STEP 2: CHARGING
The next step in the EP process is the charging step .In this step, a special wirer roller
(called a charging corona) within the EP toner cartridge (above the photosensitive drum)
gets a high voltage from the HVPS. It uses this high voltage to apply a strong, uniform
negative charge (around –600VDC) to the surface of the photosensitive drum.
STEP 3: WRITING
Next is the writing step. In this step, the laser is turned on and scans the drum from side
to side, flashing on and off according to the bits of information the printer controller
sends it as it communicates the individual bits of the image. Wherever the laser beam
touches, the photosensitive drum’s charge is severely reduced from –600VDC to a slight
negative charge (around–100VDC). As the drum rotates, a pattern of exposed areas is
formed, representing the image to be printed..
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At this point, the controller sends a signal to the pickup roller to feed a piece of paper into
the printer, where it stops at the registration rollers.
STEP 4: DEVELOPING
Now that the surface of the drum holds an electrical representation of the image being
printed, its discrete electrical charges need to be converted into something that can be
transferred to apiece of paper. The EP process step that accomplishes this is the
developing step in this step; toner is transferred to the areas that were exposed in the
writing step. A metallic roller called the developing roller inside an EP cartridge acquires
a –600VDCcharge (called a bias voltage) from the HVPS. The toner sticks to this roller
because there is a magnet located inside the roller and because of the electrostatic charges
between the toner and the developing roller. While the developing roller rotates toward
the photosensitive drum, the toner acquires the charge of the roller (–600VDC). When the
toner comes between the developing roller and the photosensitive drum, the toner is
attracted to the areas that have been exposed by the laser (because these areas have a
lesser charge, of –100VDC). The toner also is repelled from the unexposed areas
(because they are at the same –600VDC charge, and like charges repel). This toner
transfer creates a fog of toner between the EP drum and the developing roller. The
photosensitive drum now has toner stuck to it where the laser has written. The
photosensitive drum continues to rotate until the developed image is ready to be
transferred to paper in the next step.
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STEP 5: TRANSFERRING
At this point in the EP process, the developed image is rotating into position. The
controller notifies the registration rollers that the paper should be fed through. The
registration rollers move the paper underneath the photosensitive drum, and the process
of transferring the image can begin, with the transferring step. The controller sends a
signal to the charging corona wire or roller (depending on which one the printer has) and
tells it to turn on. The corona wire/roller then acquires a strong positive charge
(+600VDC) and applies that charge to the paper. The paper, thus charged, pulls the toner
from the photosensitive drum at the line of contact between the roller and the paper,
because the paper and toner have opposite charges. Once the registration rollers move the
paper past the corona wire, the static-eliminator strip removes all charge from that line of
the paper. If the strip didn’t bleed this charge away, the paper would attract itself to the
toner cartridge and cause a paper jam. The toner is now held in place by weak
electrostatic charges and gravity. It will not stay there, however, unless it is made
permanent, which is the reason for the fusing step.
STEP 6: FUSING
In the final step, the fusing step, the toner image is made permanent. The registration
rollers push the paper toward the fuser rollers. Once the user grabs the paper, the
registration rollers push for only a short time more. The fuser is now in control of moving
the paper. As the paper passes through the fuser, the 350° F fuser roller melts the
polyester resin of the toner, and the rubberized pressure roller presses it permanently into
the paper the paper continues on through the fuser and eventually exits the printer. Once
the paper completely exits the fuser, it trips a sensor that tells the printer to finish the EP
process with the cleaning step. At this point, the printer can print another page, and the
EP process can begin again.
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Summary of the EP Print Process
First, the printer uses a rubber scraper to clean the photosensitive drum. Then the printer
places a uniform –600VDC charge on the photosensitive drum by means of a charging
corona. The laser “paints” an image onto the photosensitive drum, discharging the image
areas to a much lower voltage (–100VDC). The developing roller in the toner cartridge
has charged (–600VDC) toner stuck to it. As it rolls the toner toward the photosensitive
drum, the toner is attracted to (and sticks to) the areas of the photosensitive drum that the
laser has discharged. The image is then transferred from the drum to the paper at its line
of contact by means of the transfer corona wire (or corona roller) with a +600VDC
charge. The static-eliminator strip removes the high, positive charge from the paper, and
the paper, now holding the image, moves on. The paper then enters the fuser, where a
fuser roller and the pressure roller make the image permanent. The paper exits the printer,
and the printer begins printing the next page or returns to its ready state.
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Chapter - 8
Assembling a PC
We shell see how can assemble a prefect computer. Assembling computer is a very easy
job; just need select proper components and than connect them properly.
Material Required
Screwdriver set, Noseplier.
Required Computer Parts
Main case with power supply, Monitor, Keyboard, Mouse
Motherboard, Processor, Ram
Display card, Sound card, Modem card, and LAN card if Use
Floppy drive, Hard disk drive, CD-ROM Drive, DVD R/W
Speaker/ Microphone etc.
Following steps are required to assemble a P.C.
1. Remove Cover of the System Unit (Cabinet)
Open the four screws at the back of the system’s main unit.
Slide the top cover off the System Unit (Cabinet).
Remove Base Plate from the System Unit (Cabinet)
Remove the screws holding the base plate to the System Unit (Cabinet).
Lift the base plate out of the System Unit (Cabinet).
Mount the Motherboard to the plate
Place the motherboard on the base plate using the spacers and screws
provided.
Tighten the screws provided to fix the motherboard to the base plate.
Attach the Processor to the Motherboard.
Attach the CPU to the motherboard.
Attach CPU fan to the power connector (this is very impotent, as excessive
heat build up may permanently damage the processor).
Attach the RAM modules to the Motherboard.
To attach RAM modules, properly align both side of the module
With the slot given on the motherboard.
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Mount the Mother into the Computer Unit.
Once the CPU and memory is attached to the motherboard you can mount the
back plate (with the motherboard) into the main system unit.
Attach storage Devices to the main unit.
Place the FDD, HDD and CD-ROM etc.
Tighten the side holding screws only after power and data cable are attached.
Connect Cable and front Panel to the Motherboard.
Connect power cable to the motherboard if you have ATX Power supply
then the connector will fit in only one direction.
Attach various front panel connectors to the motherboard (reset, power/HDD
LED, Speaker, Power switch etc.)
Attach drive data cable power connectors to the Storage devices.
Connect primary IDE cable and power connector to the hard disk drive.
Connect secondary IDE cable and power connector to the CD Rom, DVD.
Connect floppy drive cable and power connector to the floppy drive.
Connect external port cable.
Connect serial, parallel, game, infrared etc. port to the motherboard.
Connectors for this are provided with the motherboard.
Connect Display card and Sound card.
To connect the cards finds an empty slot.
Insert the card by first aligning cards edge connectors to the slot on the
Motherboard.
Tighten the screw to fix the card to the Motherboard.
Connect CD Audio cable.
To use you CD Drive to hear Audio CDs, connect Audio out socket on the
CD/DVD drive to the CD in connector on the soundcard/motherboard (if the
motherboard has built in soundcard.)
The cable required to make this connection is generally provided with the
CD/DVD drive.
Connect peripherals.
Connect keyboard and mouse connectors provided at the back of the system.
If you have PS/2 keyboard and mouse to used connectors PS/2 of the system.
Connect External Cables.
Connect Data cable from the monitor to the back of the display connector.
Connect mains power cord to the system’s power supply.
Connect power cord from the monitor to the power supply.
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Check Connectors.
This is very important step before switching on the system. One should
carefully check all the cards and connectors.
Switch ON the system.
Turn the mains power on.
Switch supply/UPS etc. If are you using any.
Press the power on button on the front panel of the main system unit.
Configure BIOS.
Once things are working properly you can make changes in the BIOS setup to
make the system function in a better way.
Switch Off system and close system unit’s cover.
Before closing the cover, switch off the system.
Slide the cover on the system unit and fasten the screws at the back of the
unit.
Install the required software/programs.
Ones your machine is ready, you need to install the operating system
(Windows 98/NT/2000/ME/XP/Linux etc.) into your system
Once the operating system is installed, install the software required for your
work such as the Microsoft Office, Tally DTP software such as CorelDraw,
PageMaker, Photoshop, and Venture etc.
You can also install various regional Fonts, if your job requires it.
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Second Module
Operating System
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Categories of Software
System Software: System software consists of programs used to operate the computer.
They enable the machine to accept and sum other system or application programs. They
manage resources, extend facilities and control operations.
System software includes: -
Operating System
Assembler & Compliers.
System Utilities.
Utility Software: Utility programs or routines are prewritten programs to provide
procedures commonly required by virtually are applications.
Application Software: An application is design to handle a particular task required by
the end-user.
Disk Operating System (DOS)
Operating System & It’s Functions:
Operating system is a special program, which acts as an intermediate between the user
and the computer. It stats the computer to work accordance with the user.
Ex. Dos, Windows, Linux, UNIX etc.
Function:
1. Coordinate the input output device of a computer and provide a link between
them. So that data can transfer frequently.
2. It provides a prompt on the screen through which a user can interact with the
system.
3. It loads and executes the program in the memory.
4. It manages the data file on the disk.
5. Tells computer how to start and boot-up.
6. It manages bi-directional data transfer between disk and memory.
What is DOS?
DOS is nothing more than a large program that allows you to utilize the computer. It is
the first operating system developed by IBM and Micro-Soft.
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Types of DOS –
1. PC–DOS (Developed by IBM)
2. MS–DOS (Developed by Microsoft)
Resetting the computer –
The systems can restart again in two ways –
1. Warm Booting Ctrl+Alt+Del
2. Cold Booting Turn off the system.
Structure of DOS: Three main files –
The DOS operating system is composed of three main files accompanied by roughly 80
supporting files.
1. IO.SYS
2. MS-DOS.SYS
3. COMMAND.COM
1. IO.SYS
2.
Input output system file directly interact with computer Hardware. It reset disk system
and initialize attach devices. It contains some special software to support some input and
output devices (Device drives) which are use to control the operation of keyboard,
V.D.U. Disk controller etc. It forwards programs instruction to microprocessor to get the
processing done.
MS DOS .SYS
Interact directly with application program and IO.SYS file. It acts as a bridge between
application program and IO.SYS file. It handles bi-directional data transfer that is from
disk to memory and form memory to disk
Command.Com
It is command processor. It interacts with the user directly. It accepts the command given
by the user and interprets the command. So that the computer can understand it. Than
command compresses the instruction to the MS DOS.SYS file. It gives the prompt where
a user can type command. It also perform error checking and display error manages,
when error are detected.
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Drive Space Bin
It installs DOS in a compressive form.
Dos File & Name
File
A file a similar to a piece of paper in a file folder. In Dos, every file must have a file
name of up to eight characters in length.
File Name
Name. Extension
8 Characters. 3Characters
Never use these extensions for other type of files.
. Txt - Text file
. Sys - System file (it stores the information of the system)
. Com - Program file (it has command that can be executed)
. Exe.- Extension file
. Hlp - Help file.
. Bat - Batch file
Multi level Directories
A one directory can contain maximum of 255 file and directory. These directories may
also contain some of sub-directories. This organized file structure is called a multi-level
directory.
A Directory Contain following items
1. File name
2. Extension
3. File size.
4. Date Last Modify.
5. Time last Modify.
6. Starting location of the file on the disk.
7. Attributes
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Operating System
An operating system (commonly abbreviated as either OS or O/S) is an interface
between hardware and user. An OS is responsible for the management and coordination
of activities and the sharing of the resources of the computer. The operating system acts
as a host for computing applications run on the machine. As a host, one of the purposes
of an operating system is to handle the details of the operation of the hardware. This
relieves application programs from having to manage these details and makes it easier to
write applications. Almost all computers (including handheld computers, desktop
computers, supercomputers, video game consoles) as well as some robots, domestic
appliances (dishwashers, washing machines), and portable media players use an operating
system of some type. Some of the oldest models may however use an embedded
operating system, that may be contained on a compact disk or other data storage device.
Operating systems offer a number of services to application programs and users.
Applications access these services through application programming interfaces (APIs) or
system calls. By invoking these interfaces, the application can request a service from the
operating system, pass parameters, and receive the results of the operation. Users may
also interact with the operating system with some kind of software user interface (SUI)
like typing commands by using command line interface (CLI) or using a graphical user
interface (GUI, commonly pronounced “gooey”). For hand-held and desktop computers,
the user interface is generally considered part of the operating system. On large multiuser
systems like Unix and Unix-like systems, the user interface is generally
implemented as an application program that runs outside the operating system. (Whether
the user interface should be included as part of the operating system is a point of
contention.)
Common contemporary operating system families include BSD, Darwin (Mac OS X),
GNU/Linux, SunOS (Solaris/Open Solaris), and Windows NT (XP/Vista/7). While
servers generally run UNIX or some Unix-like operating system, embedded system
markets are split amongst several operating systems.
In the beginning
Proprietary operating systems were originally made to sell the company's hardware.
Without system software (compilers and operating systems), a budding hardware
developer had real difficulty launching a computer. The availability of operating systems
not tied to a single hardware supplier - such as Digital Research's CP/M for
microcomputers, and UNIX for larger computers - greatly transformed the computer
industry. Someone with an innovative idea could easily start producing hardware on
which buyers could use standard software. In 1969-70, UNIX first appeared on the PDP-
7 and later the PDP-11.
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It soon became capable of providing cross-platform time sharing using preemptive
multitasking, advanced memory management, memory protection, and a host of other
advanced features. UNIX soon gained popularity as an operating system for mainframes
and minicomputers alike. UNIX was inspired by Multicast, as were several other
operating systems, such as Data General's AOS-VS, and IBM's addition of such concepts
as subdirectories to PC DOS in version 2.0.
Microsoft bought QDOS from Seattle Computer Products, a very simple diskette
operating system somewhat similar to CP/M, to create an operating system, PC DOS, for
the launch of the IBM PC, under a deal with IBM where Microsoft could still sell the
operating system as MS DOS for non-IBM computers. Microsoft produced oddnumbered
major version numbers while IBM was responsible for even revision numbers
(2.0, 2.1, 4.0, etc) of the code base until version 6. There was very little difference
between MS-DOS and PC-DOS, one example being the inclusion of GW-BASIC with
MS-DOS (because some BASIC code in IBM PC ROMs was not legally allowed to be
put into non-IBM computers). MS-DOS and PC-DOS soon became known simply as
"DOS" (the term is now usually taken to also include other "DOSes" such as DR-DOS
and Free DOS, but it should not be confused with the command prompt program within
some operating systems, COMMAND.COM). Although MS-DOS could be tailored to
hardware significantly different to IBM's PC, it soon became common for hardware
vendors to make their equipment as compatible as possible with the IBM PC and its
immediate IBM successors (the PC-XT and later IBM PC-AT models), since many
popular DOS programs bypassed the operating system to access hardware directly for
speed, requiring other manufactures to closely copy the IBM design, including its
limitations. The availability of MS-DOS had two major effects on the computer industry:
the commercial acceptability of "sneaky tricks" (as documented, for example, in Ralf
Brown's Interrupt List) to gain speed or functionality or copy-protection, and a market
that demanded extreme compatibility (speed and cosmetic differences were the only
acceptable innovations).
IBM PC compatibles could also run Microsoft X enix, a UNIX-like operating system
from the early 1980s. XENIX was heavily marketed by Microsoft as a multi-user
alternative to its single user MS-DOS operating system. The CPUs of these personal
computers could not facilitate kernel memory protection or provide dual mode operation,
so XENIX relied on cooperative multitasking and had no protected memory.
The 80286-based IBM PC AT was the first IBM compatible personal computer capable
of providing protected memory mode operation. However, this mode was hampered by
software bugs in its implementation on the 286, and not widely accepted until the release
of the Intel 80386. With the 386 porting BSD Unix to a PC became feasible, and various
Unix-like systems (tagged "*nix" at the time), including Linux, arose, but IBM (and,
initially, Microsoft) opted for OS/2 from the inception of the PS/2; Microsoft eventually
going its own way with Microsoft Windows firstly as a GUI on top of DOS, then as a
complete operating system.
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Classic Mac OS, and Microsoft Windows 1.0-3.11 supported only cooperative
multitasking (Windows 95, 98, & ME supported preemptive multitasking only when
running 32-bit applications, but ran legacy 16-bit applications using cooperative
multitasking), and were very limited in their abilities to take advantage of protected
memory. Application programs running on these operating systems must yield CPU time
to the scheduler when they are not using it, either by default, or by calling a function.
Windows NT's underlying operating system kernel which was designed by essentially the
same team as Digital Equipment Corporation's VMS, a UNIX-like operating system
which provided protected mode operation for all user programs, kernel memory
protection, preemptive multi-tasking, virtual file system support, and a host of other
features.
Classic Amiga OS and versions of Microsoft Windows from Windows 1.0 through
Windows Me did not properly track resources allocated by processes at runtime.[citation
needed] If a process had to be terminated, the resources might not be freed up for new
programs until the machine was restarted.
The Amiga OS did have preemptive multitasking, as did operating systems for many
larger ("supermini") computers that, despite being technically better, were struggling in
sales when faced with the mass production of increasingly-faster "Personal" Computers
and customers locked into non-portable software (legacy software and proprietary office
documents).
Mainframes
Through the 1950s, many major features were pioneered in the field of operating
systems. The development of the IBM System/360 produced a family of mainframe
computers available in widely differing capacities and price points, for which a single
operating system OS/360 was planned (rather than developing ad-hoc programs for every
individual model). This concept of a single OS spanning an entire product line was
crucial for the success of System/360 and, in fact, IBM`s current mainframe operating
systems are distant descendants of this original system; applications written for the
OS/360 can still be run on modern machines. In the mid-70, the MVS, the descendant of
OS/360 offered the firs implementation of using RAM as a transparent cache for data.
OS/360 also pioneered a number of concepts that, in some cases, are still not seen outside
of the mainframe arena. For instance, in OS/360, when a program is started, the operating
system keeps track of all of the system resources that are used including storage, locks,
data files, and so on. When the process is terminated for any reason, all of these resources
are re-claimed by the operating system. An alternative CP-67 system started a whole line
of operating systems focused on the concept of virtual machines.
Control Data Corporation developed the SCOPE operating system in the 1960s, for batch
processing. In cooperation with the University of Minnesota, the KRONOS and later the
NOS operating systems were developed during the 1970s, which supported simultaneous
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batch and timesharing use. Like many commercial timesharing systems, its interface was
an extension of the Dartmouth BASIC operating systems, one of the pioneering efforts in
timesharing and programming languages. In the late 1970s, Control Data and the
University of Illinois developed the PLATO operating system, which used plasma panel
displays and long-distance time sharing networks. Plato was remarkably innovative for its
time, featuring real-time chat, and multi-user graphical games. Burroughs Corporation
introduced the B5000 in 1961 with the MCP, (Master Control Program) operating
system. The B5000 was a stack machine designed to exclusively support high-level
languages with no machine language or assembler, and indeed the MCP was the first OS
to be written exclusively in a high-level language – ESPOL, a dialect of ALGOL. MCP
also introduced many other ground-breaking innovations, such as being the first
commercial implementation of virtual memory. During development of the AS400, IBM
made an approach to Burroughs to license MCP to run on the AS400 hardware. This
proposal was declined by Burroughs management to protect its existing hardware
production. M CP is still in use today in the Unisys Clear Path /MCP line of computers.
UNIVAC, the first commercial computer manufacturer, produced a series of EXEC
operating systems. Like all early main-frame systems, this was a batch-oriented system
that managed magnetic drums, disks, card readers and line printers. In the 1970s,
UNIVAC produced the Real-Time Basic (RTB) system to support large-scale time
sharing, also patterned after the Dartmouth BASIC system.
General Electric and MIT developed General Electric Comprehensive Operating
Supervisor (GECOS), which introduced the concept of ringed security privilege levels.
After acquisition by Honeywell it was renamed to General Comprehensive Operating
System (GCOS).
Digital Equipment Corporation developed many operating systems for its various
computer lines, including TOPS-10 and TOPS-20 time sharing systems for the 36-bit
PDP-10 class systems. Prior to the widespread use of UNIX, TOPS-10 was a particularly
popular system in universities, and in the early ARPANET community.
In the late 1960s through the late 1970s, several hardware capabilities evolved that
allowed similar or ported software to run on more than one system. Early systems had
utilized microprogramming to implement features on their systems in order to permit
different underlying architecture to appear to be the same as others in a series. In fact
most 360's after the 360/40 (except the 360/165 and 360/168) were micro programmed
implementations. But soon other means of achieving application compatibility were
proven to be more significant.
The enormous investment in software for these systems made since 1960s caused most of
the original computer manufacturers to continue to develop compatible operating systems
along with the hardware. The notable supported mainframe operating systems include:
Burroughs MCP – B5000, 1961 to Unisys Clear path/MCP, present.
IBM OS/360 – IBM System/360, 1966 to IBM z/OS, present.
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IBM CP-67 – IBM System/360, 1967 to IBM z/VM, present.
UNIVAC EXEC 8 – UNIVAC 1108, 1967, to OS 2200 Unisys Clear path
Dorado, present.
Microcomputers
The first microcomputers did not have the capacity or need for the elaborate operating
systems that had been developed for mainframes and minis; minimalist operating systems
were developed, often loaded from ROM and known as Monitors. One notable early
disk-based operating system was CP/M, which was supported on many early
microcomputers and was closely imitated in MS-DOS, which became wildly popular as
the operating system chosen for the IBM PC (IBM's version of it was called IBM DOS or
PC DOS), its successors making Microsoft. In the 80's Apple Computer Inc. (now Apple
Inc.) abandoned its popular Apple II series of microcomputers to introduce the Apple
Macintosh computer with an innovative Graphical User Interface (GUI) to the Mac OS.
The introduction of the Intel 80386 CPU chip with 32-bit architecture and paging
capabilities, provided personal computers with the ability to run multitasking operating
systems like those of earlier mini computer
Uters and mainframes. Microsoft responded to this progress by hiring Dave Cutler, who
had developed the VMS operating system for Digital Equipment Corporation. He would
lead the development of the Windows NT operating system, which continues to serve as
the basis for Microsoft's operating systems line. Steve Jobs, a co-founder of Apple Inc.,
started NeXT Computer Inc., which developed the Unix-like NEXTSTEP operating
system. NEXTSTEP would later be acquired by Apple Inc. and used, along with code
from FreeBSD as the core of Mac OS X.
Minix, an academic teaching tool which could be run on early PCs, would inspire
another reimplementation of U nix, called Linux. Started by computer science student
Linus Torvalds with cooperation from volunteers over the internet, a operating system
was developed with the tools from the GNU Project. The Berkeley Software Distribution,
known as BSD, is the UNIX derivative distributed by the University of California,
Berkeley, starting in the 1970s. Freely distributed and ported to many minicomputers, it
eventually also gained a following for use on PCs, mainly as FreeBSD, NetBSD and
Open BSD.
Features
Program execution
The operating system acts as an interface between an application and the hardware. The
user interacts with the hardware from "the other side". The operating system is a set of
services which simplifies development of applications. Executing a program involves the
creation of a process by the operating system. The kernel creates a process by assigning
memory and other resources, establishing a priority for the process (in multi-tasking
systems), loading program code into memory, and executing the program. The program
then interacts with the user and/or other devices and performs its intended function.
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Interrupts
Interrupts are central to operating systems, since they provide an efficient way for the
operating system to interact with and react to its environment. The alternative—having
the operating system "watch" the various sources of input for events (polling) that require
action—is a poor use of CPU resources. Interrupt-based programming is directly
supported by most CPUs. Interrupts provide a computer with a way of automatically
running specific code in response to events. Even very basic computers support hardware
interrupts, and allow the programmer to specify code which may be run when that event
takes place.
When an interrupt is received, the computer's hardware automatically suspends whatever
program is currently running, saves its status, and runs computer code previously
associated with the interrupt; this is analogous to placing a bookmark in a book in
response to a phone call. In modern operating systems, interrupts are handled by the
operating system's kernel. Interrupts may come from either the computer's hardware or
from the running program.
When a hardware device triggers an interrupt the operating system's kernel decides how
to deal with this event, generally by running some processing code. How much code gets
run depends on the priority of the interrupt (for example: a person usually responds to a
smoke detector alarm before answering the phone). The processing of hardware interrupts
is a task that is usually delegated to software called device drivers, which may be either
part of the operating system's kernel, part of another program, or both. Device drivers
may then relay information to a running program by various means.
A program may also trigger an interrupt to the operating system. If a program wishes to
access hardware for example, it may interrupt the operating system's kernel, which causes
control to be passed back to the kernel. The kernel will then process the request. If a
program wishes additional resources (or wishes to shed resources) such as memory, it
will trigger an interrupt to get the kernel's attention.
Protected mode and supervisor mode
Modern CPUs support something called dual mode operation. CPUs with this capability
use two modes: protected mode and supervisor mode, which allow certain CPU functions
to be controlled and affected only by the operating system kernel. Here, protected mode
does not refer specifically to the 80286 (Intel's x86 16-bit microprocessor) CPU feature,
although its protected mode is very similar to it. CPUs might have other modes similar to
80286 protected mode as well, such as the virtual 8086 mode of the 80386 (Intel's x86
32-bit microprocessor or i386).
However, the term is used here more generally in operating system theory to refer to all
modes which limit the capabilities of programs running in that mode, providing things
like virtual memory addressing and limiting access to hardware in a manner determined
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by a program running in supervisor mode. Similar modes have existed in supercomputers,
minicomputers, and mainframes as they are essential to fully supporting UNIX-like
multi-user operating systems.
When a computer first starts up, it is automatically running in supervisor mode. The first
few programs to run on the computer, being the BIOS, boot loader and the operating
system have unlimited access to hardware - and this is required because, by definition,
initializing a protected environment can only be done outside of one. However, when the
operating system passes control to another program, it can place the CPU into protected
mode.
In protected mode, programs may have access to a more limited set of the CPU's
instructions. A user program may leave protected mode only by triggering an interrupt,
causing control to be passed back to the kernel. In this way the operating system can
maintain exclusive control over things like access to hardware and memory.
The term "protected mode resource" generally refers to one or more CPU registers, which
contain information that the running program isn't allowed to alter. Attempts to alter
these resources generally cause a switch to supervisor mode, where the operating system
can deal with the illegal operation the program was attempting (for example, by killing
the program).
Memory management
Among other things, a multiprogramming operating system kernel must be responsible
for managing all system memory which is currently in use by programs. This ensures that
a program does not interfere with memory already used by another program. Since
programs time share, each program must have independent access to memory.
Cooperative memory management, used by many early operating systems assumes that
all programs make voluntary use of the kernel's memory manager, and do not exceed
their allocated memory. This system of memory management is almost never seen
anymore, since programs often contain bugs which can cause them to exceed their
allocated memory. If a program fails it may cause memory used by one or more other
programs to be affected or overwritten. Malicious programs, or viruses may purposefully
alter another program's memory or may affect the operation of the operating system
itself. With cooperative memory management it takes only one misbehaved program to
crash the system.
Memory protection enables the kernel to limit a process' access to the computer's
memory. Various methods of memory protection exist, including memory segmentation
and paging. All methods require some level of hardware support (such as the 80286
MMU) which doesn't exist in all computers.
In both segmentation and paging, certain protected mode registers specify to the CPU
what memory address it should allow a running program to access. Attempts to access
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other addresses will trigger an interrupt which will cause the CPU to re-enter supervisor
mode, placing the kernel in charge. This is called a segmentation violation or Seg-V for
short, and since it is both difficult to assign a meaningful result to such an operation, and
because it is usually a sign of a misbehaving program, the kernel will generally resort to
terminating the offending program, and will report the error.
Windows 3.1-Me had some level of memory protection, but programs could easily
circumvent the need to use it. Under Windows 9x all MS-DOS applications ran in
supervisor mode, giving them almost unlimited control over the computer. A general
protection fault would be produced indicating a segmentation violation had occurred,
however the system would often crash anyway.
In most Linux systems, part of the hard disk is reserved for virtual memory when the
Operating system is being installed on the system. This part is known as swap space.
Windows systems use a swap file instead of a partition.
Virtual memory
The use of virtual memory addressing (such as paging or segmentation) means that the
kernel can choose what memory each program may use at any given time, allowing the
operating system to use the same memory locations for multiple tasks.
If a program tries to access memory that isn't in its current range of accessible memory,
but nonetheless has been allocated to it, the kernel will be interrupted in the same way as
it would if the program were to exceed its allocated memory. (See section on memory
management.) Under UNIX this kind of interrupt is referred to as a page fault.
When the kernel detects a page fault it will generally adjust the virtual memory range of
the program which triggered it, granting it access to the memory requested. This gives the
kernel discretionary power over where a particular application's memory is stored, or
even whether or not it has actually been allocated yet.
In modern operating systems, memory which is accessed less frequently can be
temporarily stored on disk or other media to make that space available for use by other
programs. This is called swapping, as an area of memory can be used by multiple
programs, and what that memory area contains can be swapped or exchanged on demand.
Multitasking
Multitasking refers to the running of multiple independent computer programs on the
same computer; giving the appearance that it is performing the tasks at the same time.
Since most computers can do at most one or two things at one time, this is generally done
via time sharing, which means that each program uses a share of the computer's time to
execute.
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An operating system kernel contains a piece of software called a scheduler which
determines how much time each program will spend executing, and in which order
execution control should be passed to programs. Control is passed to a process by the
kernel, which allows the program access to the CPU and memory. At a later time control
is returned to the kernel through some mechanism, so that another program may be
allowed to use the CPU. This so-called passing of control between the kernel and
applications is called a context switch.
An early model which governed the allocation of time to programs was called
cooperative multitasking. In this model, when control is passed to a program by the
kernel, it may execute for as long as it wants before explicitly returning control to the
kernel. This means that a malicious or malfunctioning program may not only prevent any
other programs from using the CPU, but it can hang the entire system if it enters an
infinite loop.
The philosophy governing preemptive multitasking is that of ensuring that all programs
are given regular time on the CPU. This implies that all programs must be limited in how
much time they are allowed to spend on the CPU without being interrupted. To
accomplish this, modern operating system kernels make use of a timed interrupt. A
protected mode timer is set by the kernel which triggers a return to supervisor mode after
the specified time has elapsed. (See above sections on Interrupts and Dual Mode
Operation.)
On many single user operating systems cooperative multitasking is perfectly adequate, as
home computers generally run a small number of well tested programs. Windows NT was
the first version of Microsoft Windows which enforced preemptive multitasking, but it
didn't reach the home user market until Windows XP, (since Windows NT was targeted
at professionals.)
Kernel preemption
In recent years, concerns have arisen because of long latencies associated with some
kernel run-times, sometimes on the order of 100ms or more in systems with monolithic
kernels. These latencies often produce noticeable slowness in desktop systems, and can
prevent operating systems from performing time-sensitive operations such as audio
recording and some communications.
Modern operating systems extend the concepts of application preemption to device
drivers and kernel code, so that the operating system has preemptive control over internal
run-times as well. Under Windows Vista, the introduction of the Windows Display
Driver Model (WDDM) accomplishes this for display drivers, and in Linux, the preempt
able kernel model introduced in version 2.6 allows all device drivers and some other parts
of kernel code to take advantage of preemptive multi-tasking.
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Under Windows prior to Windows Vista and Linux prior to version 2.6 all driver
execution was co-operative, meaning that if a driver entered an infinite loop it would
freeze the system.
Disk access and file systems
Access to data stored on disks is a central feature of all operating systems. Computers
store data on disks using files, which are structured in specific ways in order to allow for
faster access, higher reliability, and to make better use out of the drive's available space.
The specific way in which files are stored on a disk is called a file system, and enables
files to have names and attributes. It also allows them to be stored in a hierarchy of
directories or folders arranged in a directory tree.
Early operating systems generally supported a single type of disk drive and only one kind
of file system. Early file systems were limited in their capacity, speed, and in the kinds of
file names and directory structures they could use. These limitations often reflected
limitations in the operating systems they were designed for, making it very difficult for
an operating system to support more than one file system.
While many simpler operating systems support a limited range of options for accessing
storage systems, operating systems like UNIX and Linux support a technology known as
a virtual file system or VFS. An operating system like UNIX supports a wide array of
storage devices, regardless of their design or file systems to be accessed through a
common app lication programming interface (API). This makes it unnecessary for
programs to have any knowledge about the device they are accessing. A VFS allows the
operating system to provide programs with access to an unlimited number of devices with
an infinite variety of file systems installed on them through the use of specific device
drivers and file system drivers.
A connected storage device such as a hard drive is accessed through a device driver. The
device driver understands the specific language of the drive and is able to translate that
language into a standard language used by the operating system to access all disk drives.
On UNIX this is the language of block devices.
When the kernel has an appropriate device driver in place, it can then access the contents
of the disk drive in raw format, which may contain one or more file systems. A file
system driver is used to translate the commands used to access each specific file system
into a standard set of commands that the operating system can use to talk to all file
systems. Programs can then deal with these files systems on the basis of filenames, and
directories/folders, contained within a hierarchical structure. They can create, delete,
open, and close files, as well as gather various information about them, including access
permissions, size, and free space, and creation and modification dates.
Various differences between file systems make supporting all file systems difficult.
Allowed characters in file names, case sensitivity, and the presence of various kinds of
file attributes makes the implementation of a single interface for every file system a
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daunting task. Operating systems tend to recommend the use of (and so support natively)
file systems specifically designed for them; for example, NTFS in Windows and ext3 and
Reiser FS in Linux. However, in practice, third party drives are usually available to give
support for the most widely used file systems in most general-purpose operating systems
(for example, NTFS is available in Linux through NTFS-3g, and ext2/3 and Reiser FS are
available in Windows through FSdriver and rfstool).
Device drivers
A device driver is a specific type of computer software developed to allow interaction
with hardware devices. Typically this constitutes an interface for communicating with the
device, through the specific computer bus or communications subsystem that the
hardware is connected to, providing commands to and/or receiving data from the device,
and on the other end, the requisite interfaces to the operating system and software
applications. It is a specialized hardware-dependent computer program which is also
operating system specific that enables another program, typically an operating system or
applications software package or computer program running under the operating system
kernel, to interact transparently with a hardware device, and usually provides the requisite
interrupt handling necessary for any necessary asynchronous time-dependent hardware
interfacing needs.
The key design goal of device drivers is abstraction. Every model of hardware (even
within the same class of device) is different. Newer models also are released by
manufacturers that provide more reliable or better performance and these newer models
are often controlled differently. Computers and their operating systems cannot be
expected to know how to control every device, both now and in the future. To solve this
problem, OSes essentially dictate how every type of device should be controlled. The
function of the device driver is then to translate these OS mandated function calls into
device specific calls. In theory a new device, which is controlled in a new manner, should
function correctly if a suitable driver is available. This new driver will ensure that the
device appears to operate as usual from the operating systems' point of view.
Networking
Currently most operating systems support a variety of networking protocols, hardware,
and applications for using them. This means that computers running dissimilar operating
systems can participate in a common network for sharing resources such as computing,
files, printers, and scanners using either wired or wireless connections. Networks can
essentially allow a computer's operating system to access the resources of a remote
computer to support the same functions as it could if those resources were connected
directly to the local computer. This includes everything from simple communication, to
using networked file systems or even sharing another computer's graphics or sound
hardware. Some network services allow the resources of a computer to be accessed
transparently, such as SSH which allows networked users direct access to a computer's
command line interface.
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Client/server networking involves a program on a computer somewhere which connects
via a network to another computer, called a server. Servers, usually running UNIX or
Linux, offer (or host) various services to other network computers and users. These
services are usually provided through ports or numbered access points beyond the
server's network address. Each port number is usually associated with a maximum of one
running program, which is responsible for handling requests to that port. A daemon,
being a user program, can in turn access the local hardware resources of that computer by
passing requests to the operating system kernel.
Many operating systems support one or more vendor-specific or open networking
protocols as well, for example, SNA on IBM systems, DE Cent on systems from Digital
Equipment Corporation, and Microsoft-specific protocols (SMB) on Windows. Specific
protocols for specific tasks may also be supported such as NFS for file access. Protocols
like E sound, or esd can be easily extended over the network to provide sound from local
applications, on a remote system's sound hardware.
Security
A computer being secure depends on a number of technologies working properly. A
modern operating system provides access to a number of resources, which are available
to software running on the system, and to external devices like networks via the kernel.
The operating system must be capable of distinguishing between requests which should
be allowed to be processed, and others which should not be processed. While some
systems may simply distinguish between "privileged" and "non-privileged", systems
commonly have a form of requester identity, such as a user name. To establish identity
there may be a process of authentication. Often a username must be quoted, and each
username may have a password. Other methods of authentication, such as magnetic cards
or biometric data, might be used instead. In some cases, especially connections from the
network, resources may be accessed with no authentication at all (such as reading files
over a network share). Also covered by the concept of requester identity is authorization;
the particular services and resources accessible by the requester once logged into a
system and tied to either the requester's user account or to the variously configured
groups of users to which the requester belongs.
In addition to the allow/disallow model of security, a system with a high level of security
will also offer auditing options. These would allow tracking of requests for access to
resources (such as, "who has been reading this file?"). Internal security or security from
an already running program is only possible if all possibly harmful requests must be
carried out through interrupts to the operating system kernel. If programs can directly
access hardware and resources, they cannot be secured.
External security involves a request from outside the computer, such as a login at a
connected console or some kind of network connection. External requests are often
passed through device drivers to the operating system's kernel, where they can be passed
onto applications, or carried out directly. Security of operating systems has long been a
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concern because of highly sensitive data held on computers, both of a commercial and
military nature. The United States Government Department of Defense (DoD) created the
Trusted Computer System Evaluation Criteria (TCSEC) which is a standard that sets
basic requirements for assessing the effectiveness of security. This became of vital
importance to operating system makers, because the TCSEC was used to evaluate,
classify and select computer systems being considered for the processing, storage and
retrieval of sensitive or classified information.
Network services include offerings such as file sharing, print services, email, web sites,
and file transfer protocols (FTP), most of which can have compromised security. At the
front line of security are hardware devices known as firewalls or intrusion
detection/prevention systems. At the operating system level, there are a number of
software firewalls available, as well as intrusion detection/prevention systems. Most
modern operating systems include a software firewall, which is enabled by default. A
software firewall can be configured to allow or deny network traffic to or from a service
or application running on the operating system. Therefore, one can install and be running
an insecure service, such as Telnet or FTP, and not have to be threatened by a security
breach because the firewall would deny all traffic trying to connect to the service on that
port.
An alternative strategy, and the only sandbox strategy available in systems that do not
meet the Popek and Goldberg virtualization requirements, is the operating system not
running user programs as native code, but instead either emulates a processor or provides
a host for a p-code based system such as Java.
Internal security is especially relevant for multi-user systems; it allows each user of the
system to have private files that the other users cannot tamper with or read. Internal
security is also vital if auditing is to be of any use, since a program can potentially bypass
the operating system, inclusive of bypassing auditing.
Microsoft Windows
While the Windows 9x series offered the option of having profiles for multiple users,
they had no concept of access privileges, and did not allow concurrent access; and so
were not true multi-user operating systems. In addition, they implemented only partial
memory protection. They were accordingly widely criticized for lack of security.
The Windows NT series of operating systems, by contrast, are true multi-user, and
implement absolute memory protection. However, a lot of the advantages of being a true
multi-user operating system were nullified by the fact that, prior to Windows Vista, the
first user account created during the setup process was an administrator account, which
was also the default for new accounts. Though Windows XP did have limited accounts,
the majority of home users did not change to an account type with fewer rights – partially
due to the number of programs which unnecessarily required administrator rights – and
so most home users ran as administrator all the time.
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Windows Vista changes this by introducing a privilege elevation system called User
Account Control. When logging in as a standard user, a logon session is created and a
token containing only the most basic privileges is assigned. In this way, the new logon
session is incapable of making changes that would affect the entire system. When logging
in as a user in the Administrators group, two separate tokens are assigned. The first token
contains all privileges typically awarded to an administrator, and the second is a restricted
token similar to what a standard user would receive. User applications, including the
Windows Shell, are then started with the restricted token, resulting in a reduced privilege
environment even under an Administrator account. When an application requests higher
privileges or "Run as administrator" is clicked, UAC will prompt for confirmation and, if
consent is given (including administrator credentials if the account requesting the
elevation is not a member of the administrators group), start the process using the
unrestricted token.
Linux/Unix
Linux and UNIX both have two tier securities, which limit any system-wide changes to
the root user, a special user account on all UNIX-like systems. While the root user has
virtually unlimited permission to effect system changes, programs running as a regular
user are limited in where they can save files, what hardware they can access, etc. In many
systems, a user's memory usage, their selection of available programs, their total disk
usage or quota, available range of programs' priority settings, and other functions can also
be locked down. This provides the user with plenty of freedom to do what needs to be
done, without being able to put any part of the system in jeopardy (barring accidental
triggering of system-level bugs) or make sweeping, system-wide changes. The user's
settings are stored in an area of the computer's file system called the user's home
directory, which is also provided as a location where the user may store their work, a
concept later adopted by Windows as the 'My Documents' folder. Should a user have to
install software outside of his home directory or make system-wide changes, they must
become the root user temporarily, usually with the su or sudo command, which is
answered with the computer's root password when prompted. Some systems (such as
Ubuntu and its derivatives) are configured by default to allow select users to run
programs as the root user via the sudo command, using the user's own password for
authentication instead of the system's root password. One is sometimes said to "go root"
or "drop to root" when elevating oneself to root access.
File system support in modern operating systems
Support for file systems is highly varied among modern operating systems although there
are several common file systems which almost all operating systems include support and
drivers for.
Solaris
The Solaris Operating System (as with most operating systems based upon open
standards and/or open source) uses UFS as its primary file system. Prior to 1998, Solaris
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UFS did not have logging/journaling capabilities, but over time the OS has gained this
and other new data management capabilities.
Additional features include Vertis (Journaling) Vx FS, QFS from Sun Microsystems,
enhancements to UFS including multiyear byte support and UFS volume management
included as part of the OS, and ZFS (open source, pool able, 128-bit, compressible, and
error-correcting).
Kernel extensions were added to Solaris to allow for bootable VERITAS Vexes
operation. Logging or journaling was added to UFS in Solaris 7. Releases of Solaris 10,
Solaris Express, Open Solaris, and other open source variants of Solaris later supported
bootable ZFS.
Logical Volume Management allows for spanning a file system across multiple devices
for the purpose of adding redundancy, capacity, and/or throughput. Solaris includes
Solaris Volume Manager (formerly known as Solstice Disk Suite.) Solaris is one of many
operating systems supported by VERITAS Volume Manager. Modern Solaris based
operating systems eclipse the need for volume management through leveraging virtual
storage pools in ZFS.
Linux
Many Linux distributions support some or all of ext2, ext3, ext4, Reiser FS, Reiser4, JFS
, XFS , GFS, GFS2, OCFS, OCFS2, and NILFS. The ext file systems, namely ext2, ext3
and ext4 are based on the original Linux file system. Others have been developed by
companies to meet their specific needs, hobbyists, or adapted from UNIX, Microsoft
Windows, and other operating systems. Linux has full support for XFS and JFS, along
with FAT (the MS-DOS file system), and HFS which is the primary file system for the
Macintosh.
In recent years support for Microsoft Windows NT's NTFS file system has appeared in
Linux, and is now comparable to the support available for other native UNIX file
systems. ISO 9660 and Universal Disk Format (UDF) are supported which are standard
file systems used on CDs, DVDs, and Blu Ray discs. It is possible to install Linux on the
majority of these file systems. Unlike other operating systems, Linux and UNIX allow
any file system to be used regardless of the media it is stored in, whether it is a hard
drive, a disc (CD,DVD...), an USB key, or even contained within a file located on another
file system.
Microsoft Windows
Microsoft Windows currently supports NTFS and FAT file systems, along with network
file systems shared from other computers, and the ISO 9660 and UDF file systems used
for CDs, DVDs, and other optical discs such as Blu-ray. Under Windows each file system
is usually limited in application to certain media, for example CDs must use ISO 9660 or
UDF, and as of Windows Vista, NTFS is the only file system which the operating system
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can be installed on. Windows Embedded CE 6.0, Windows Vista Service Pack 1, and
Windows Server 2008 support Ex FAT, a file system more suitable for flash drives.
Mac OS X
Mac OS X supports HFS+ with journaling as its primary file system. It is derived from
the Hierarchical File System of the earlier Mac OS. Mac OS X has facilities to read and
write FAT, NTFS (read-only, although an open-source cross platform implementation
known as NTFS 3G provides read-write support to Microsoft Windows NTFS file system
for Mac OS X users), UDF, and other file systems, but cannot be installed to them. Due
to its UNIX heritage Mac OS X now supports virtually all the file systems supported by
the UNIX VFS. Recently Apple Inc. started work on porting Sun Microsystems' ZFS file
system to Mac OS X and preliminary support is already available in Mac OS X 10.5 as
well as support for Blu-ray discs.
Special-purpose file systems
FAT file systems are commonly found on floppy disks, flash memory cards, digital
cameras, and many other portable devices because of their relative simplicity.
Performance of FAT compares poorly to most other file systems as it uses overly
simplistic data structures, making file operations time-consuming, and makes poor use of
disk space in situations where many small files are present. ISO 9660 and Universal Disk
Format are two common formats that target Compact Discs and DVDs. Mount Rainier is
a newer extension to UDF supported by Linux 2.6 series and Windows Vista that
facilitates rewriting to DVDs in the same fashion as has been possible with floppy disks.
Journalized file systems
File systems may provide journaling, which provides safe recovery in the event of a
system crash. A journeyed file system writes some information twice: first to the journal,
which is a log of file system operations, then to its proper place in the ordinary file
system. Journaling is handled by the file system driver, and keeps track of each operation
taking place that changes the contents of the disk. In the event of a crash, the system can
recover to a consistent state by replaying a portion of the journal. Many UNIX file
systems provide journaling including ReiserFS, JFS, and Ext3.
In contrast, non-journeyed file systems typically need to be examined in their entirety by
a utility such as fsck or chkdsk for any inconsistencies after an unclean shutdown. Soft
updates is an alternative to journaling that avoids the redundant writes by carefully
ordering the update operations. Log-structured file systems and ZFS also differ from
traditional journeyed file systems in that they avoid inconsistencies by always writing
new copies of the data, eschewing in-place updates.
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Graphical user interfaces
Most of the modern computer systems support graphical user interfaces (GUI), and often
include them. In some computer systems, such as the original implementations of
Microsoft Windows and the Mac OS, the GUI is integrated into the kernel.
While technically a graphical user interface is not an operating system service,
incorporating support for one into the operating system kernel can allow the GUI to be
more responsive by reducing the number of context switches required for the GUI to
perform its output functions. Other operating systems are modular, separating the
graphics subsystem from the kernel and the Operating System. In the 1980s UNIX, VMS
and many others had operating systems that were built this way. Linux and Mac OS X are
also built this way. Modern releases of Microsoft Windows such as Windows Vista
implement a graphics subsystem that is mostly in user-space; however versions between
Windows NT 4.0 and Windows Server 2003's graphics drawing routines exist mostly in
kernel space. Windows 9x had very little distinction between the interface and the kernel.
Many computer operating systems allow the user to install or create any user interface
they desire. The X Window System in conjunction with GNOME or KDE is a
commonly-found setup on most UNIX and UNIX-like (BSD, Linux, Minix) systems. A
number of Windows shell replacements have been released for Microsoft Windows,
which offer alternatives to the included Windows shell, but the shell itself cannot be
separated from Windows.
Numerous Unix-based GUIs have existed over time, most derived from X11.
Competition among the various vendors of UNIX (HP, IBM, and Sun) led to much
fragmentation, though an effort to standardize in the 1990s to COSE and CDE failed for
the most part due to various reasons, eventually eclipsed by the widespread adoption of
GNOME and KDE. Prior to open source-based toolkits and desktop environments, Motif
was the prevalent toolkit/desktop combination (and was the basis upon which CDE was
developed).
Graphical user interfaces evolve over time. For example, Windows has modified its user
interface almost every time a new major version of Windows is released, and the Mac OS
GUI changed dramatically with the introduction of Mac OS X in 1999.
Microsoft Windows
Microsoft Windows is a family of proprietary operating systems that originated as an
add-on to the older MS-DOS operating system for the IBM PC. Modern versions are
based on the newer Windows NT kernel that was originally intended for OS/2. Windows
runs on x86, x86-64 and Itanium processors. Earlier versions also ran on the DEC Alpha,
MIPS, Fairchild (later Intergraph) Clipper and PowerPC architectures (some work was
done to port it to the SPARC architecture).
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As of June 2008, Microsoft Windows holds a large amount of the worldwide desktop
market share. Windows is also used on servers, supporting applications such as web
servers and database servers. In recent years, Microsoft has spent significant marketing
and research & development money to demonstrate that Windows is capable of running
any enterprise application, which has resulted in consistent price/performance records
(see the TPC) and significant acceptance in the enterprise market.
The most widely used version of the Microsoft Windows family is Windows XP, released
on October 25, 2001.
In November 2006, after more than five years of development work, Microsoft released
Windows Vista, a major new operating system version of Microsoft Windows family
which contains a large number of new features and architectural changes. Chief amongst
these are a new user interface and visual style called Windows Aero, a number of new
security features such as User Account Control, and a few new multimedia applications
such as Windows DVD Maker. A server variant based on the same kernel, Windows
Server 2008, was released in early 2008.
Windows 7 is currently under development; Microsoft has stated that it intends to scope
its development to a three-year timeline; it is to be released on October 22, 2009.
Unix and unix-like operating systems
Debian is a (Linux-based) UNIX-like system
Ken Thompson wrote B, mainly based on BCPL, which he used to write UNIX, based on
his experience in the MULTICS project. B was replaced by C, and Unix developed into a
large, complex family of inter-related operating systems which have been influential in
every modern operating system .The Unix-like family is a diverse group of operating
systems, with several major sub-categories including System V, BSD, and Linux. The
name "UNIX" is a trademark of The Open Group which licenses it for use with any
operating system that has been shown to conform to their definitions. "Unix-like" is
commonly used to refer to the large set of operating systems which resemble the original
UNIX.
Unix-like systems run on a wide variety of machine architectures. They are used heavily
for servers in business, as well as workstations in academic and engineering
environments. Free UNIX variants, such as GNU, Linux and BSD, are popular in these
areas.
Some UNIX variants like HP's HP-UX and IBM's AIX are designed to run only on that
vendor's hardware. Others, such as Solaris, can run on multiple types of hardware,
including x86 servers and PCs. Apple's Mac OS X, a hybrid kernel-based BSD variant
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derived from NeXT STEP, Mach, and FreeBSD, has replaced Apple's earlier (non-Unix)
Mac OS.
UNIX interoperability was sought by establishing the POSIX standard. The POSIX
standard can be applied to any operating system, although it was originally created for
various UNIX variants.
Mac OS X
Mac OS X "Snow Leopard"
Mac OS X is a line of partially proprietary, graphical operating systems developed,
marketed, and sold by Apple Inc., the latest of which is pre-loaded on all currently
shipping Macintosh computers. Mac OS X is the successor to the original Mac OS, which
had been Apple's primary operating system since 1984. Unlike its predecessor, Mac OS
X is a UNIX operating system built on technology that had been developed at NeXT
through the second half of the 1980s and up until Apple purchased the company in early
1997.
The operating system was first released in 1999 as Mac OS X Server 1.0, with a desktoporiented
version (Mac OS X v10.0) following in March 2001. Since then, six more
distinct "client" and "server" editions of Mac OS X have been released, the most recent
being Mac OS X v10.6, which was first made available on August 28, 2009. Releases of
Mac OS X are named after big cats; the current version of Mac OS X is nicknamed
"Snow Leopard".
The server edition, Mac OS X Server, is architecturally identical to its desktop
counterpart but usually runs on Apple's line of Macintosh server hardware. Mac OS X
Server includes work group management and administration software tools that provide
simplified access to key network services, including a mail transfer agent, a Samba
server, an LDAP server, a domain name server, and others.
Plan 9
Ken Thompson, Dennis Ritchie and Douglas McIlroy at Bell Labs designed and
developed the C programming language to build the operating system Unix.
Programmers at Bell Labs went on to develop Plan 9 and Inferno, which were engineered
for modern distributed environments. Plan 9 was designed from the start to be a
networked operating system, and had graphics built-in, unlike Unix, which added these
features to the design later. Plan 9 has yet to become as popular as Unix derivatives, but it
has an expanding community of developers. It is currently released under the Lucent
Public License. Inferno was sold to Vita Nuova Holdings and has been released under a
GPL/MIT license.
Real-time operating systems
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A real-time operating system (RTOS1) is a multitasking operating system intended for
applications with fixed deadlines (real-time computing). Such applications include some
small embedded systems, automobile engine controllers, industrial robots, spacecraft,
industrial control, and some large-scale computing systems.
An early example of a large-scale real-time operating system was Transaction Processing
Facility developed by American Airlines and IBM for the Sabre Airline Reservations
System.
Embedded systems
Embedded systems use a variety of dedicated operating systems. In some cases, the
"operating system" software is directly linked to the application to produce a monolithic
special-purpose program. In the simplest embedded systems, there is no distinction
between the OS and the application.
Embedded systems that have fixed deadlines use a real-time operating system such as
VxWorks, eCos, QNX, MontaVista Linux and RTLinux. Windows CE is a real-time
operating system that shares similar APIs to desktop Windows but shares none of desktop
Windows' codebase
Some embedded systems use operating systems such as Symbian OS, Palm OS, BSD,
and Linux, although such operating systems do not support real-time computing.
Hobby development
Operating system development or OSDev for short, as a hobby has a large cult-like
following. As such, operating systems, such as Linux, have derived from hobby operating
system projects. The design and implementation of an operating system requires skill and
determination, and the term can cover anything from a basic "Hello World" boot loader to
a fully featured kernel. One classical example of this is the Minix Operating System—an
OS that was designed by A.S. Tanenbaum as a teaching tool but was heavily used by
hobbyists before Linux eclipsed it in popularity.
Other
Older operating systems which are still used in niche markets include OS/2 from IBM
and Microsoft; Mac OS, the non-Unix precursor to Apple's Mac OS X; BeOS; XTS-300.
Some, most notably AmigaOS 4 and RISC OS, continue to be developed as minority
platforms for enthusiast communities and specialist applications. OpenVMS formerly
from DEC is still under active development by Hewlett-Packard. There were a number of
operating systems for 8 bit computers - Apple's DOS (Disk Operating System) 3.2 & 3.3
for Apple II, Pro DOS, UCSD, CP/M - available for various 8 and 16 bit environments,
FutureOS for the Amstrad CPC6128 and 6128Plus.
119
Research and development of new operating systems continues. GNU Hurd is designed
to be backwards compatible with UNIX, but with enhanced functionality and a
microkernel architecture. Singularity is a project at Microsoft Research to develop an
operating system with better memory protection based on the .Net managed code model.
Systems development follows the same model used by other Software development,
which involves maintainers, version control "trees”, forks, "patches", and specifications.
From the AT&T-Berkeley lawsuit the new unencumbered systems were based on
4.4BSD which forked as FreeBSD and NetBSD efforts to replace missing code after the
UNIX wars. Recent forks include DragonFly BSD and Darwin from BSD Unix
Diversity of operating systems and protability
Application software is generally written for use on a specific operating system, and
sometimes even for specific hardware. When porting the application to run on another
OS, the functionality required by that application may be implemented differently by that
OS (the names of functions, meaning of arguments, etc.) requiring the application to be
adapted.
This cost in supporting operating systems diversity can be avoided by instead writing
applications against software platforms like Java, Qt or for web browsers. These
abstractions have already borne the cost of adaptation to specific operating systems and
their system libraries.
Another approach is for operating system vendors to adopt standards. For example,
POSIX and OS abstraction layers provide commonalities that reduce porting costs.
Application Software
Application software is a computer program that functions and is operated by means of a
computer, with the purpose of supporting or improving the software user's work. In other
words, it is the subclass of computer software that employs the capabilities of a computer
directly and thoroughly to a task that the user wishes to perform. This should be
contrasted with system software (infrastructure) or middleware (computer services/
processes integrators), which is involved in integrating a computer's various capabilities,
but typically does not directly apply them in the performance of tasks that benefit the
user. In this context the term application refers to both the application software and its
implementation
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Microsoft windows Operating System Requirements
Windows 98
CPU Required : 486 DX66MHz and Faster
Ram : 16 MB and 32 MB
Hard Disk : 335 MB Space
Compact Disk (CD, DVD) : Up to 12X Speed
Floppy : On Boot Time
Display : 16 bit and 24 bit (VGA)
Pointer Device : Key Board, Mouse
Serial Key : HJGWK-GBD78-C7Q8D-4BKY9-P4RR6
Windows ME
CPU Required : 150 MHz or higher
Ram : 32 MB of RAM
Hard Disk : 420 MB (Depending on configuration selected)
Compact Disk (CD, DVD) : Up to 12X Speed
Floppy : On Boot Time
Display : 16 bit and 24 bit (VGA)
Pointer Device : Key Board, Mouse
Serial Key : 11111-11111-11111-11111-11111
Windows NT (4.0 Workstation)
CPU Required : Pentium 1
Ram : 16 MB of Ram
Hard Disk : Up to 110 MB
Compact Disk (CD, DVD) : Up to 12X Speed
Floppy : Not So Required
Display : VGA (800x600)
Pointer Device : Key Board, Mouse
Serial key : 145-111
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Windows 2000 Professional
CPU Required : 133 MHz
Ram : 64 MB 0f Ram
Hard Disk : 650 MB Space
Compact Disk (CD, DVD) : Up to 12X Speed
Floppy : Not So Required
Display : SVGA (1024x768)
Pointer Device : Key Board, Mouse
Serial Key : RBDC8-VTRC8-D7972-J97JY-PRVMG
Windows XP Professional
CPU Required : 233 MHz
Ram : Up to 64 MB
Hard Disk : 1.5 GB (1500MB)
Compact Disk (CD, DVD) : Up to 12X Speed
Floppy : Not So Required
Display : SVGA (1024x768)
Pointer Device : Key Board, Mouse
Serial key : YVGKQ-B7QYX-WWPBR-M7T2R-PB8BM
: 72HHJ-8YR4B-2XT62-TJGMV-JBP68
Windows Server 2003 Standard Edition
CPU Required : 133 MHz
Ram : 128 of Ram
Hard Disk : 1.5 GB (1500MB)
Compact Disk (CD, DVD) : Up to 12X Speed
Floppy : Not So Required
Display : SVGA (1024x768)
Pointer Device : Key Board, Mouse
Serial Key : JB88F-WT2Q3-DPXTT-Y8GHG-7YYQY
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Windows Vista, Business
CPU Required : Up to 1 GHz
Ram : 512 MB of Ram
Hard Disk : 20 GB
Compact Disk (CD, DVD) : DVD Rom
Floppy : Not So Required
Display : SVGA (1024x768) With 32 MB of Memory
Pointer Device : Key Board, Mouse
Serial Key : YFKBB-PQJJV-G996G-VWGXY -2V3X8
Windows 7, Business
CPU Required : Up to 1 GHz
Ram : 512 MB of Ram
Hard Disk : 20 GB
Compact Disk (CD, DVD) : DVD Rom
Floppy : Not So Required
Display : SVGA (1024x768) With 32 MB of Memory
Pointer Device : Key Board, Mouse
Serial Key : Not Required
Server 2008, Standard Edition
CPU Required : Up to 1.4 GHz
Ram : 1 GB of Ram
Hard Disk : 20 GB
Compact Disk (CD, DVD) : DVD Rom
Floppy : Not So Required
Display : SVGA (1024x768) With 32 MB of Memory
Pointer Device : Key Board, Mouse
Serial Key : Not Required
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Operating Software Installation
Windwos98, Windows ME, Windows2000 Prof. Windows XP Prof, Windows
Server2003, Windows Vista, Windwos7, Windows Server2008, Red Hat Apple Inc.
Hewlett Packard Intel Corporationand Other……….
Dual Booting of Operating Software
Windwos98 :Windows2000 Prof, Windows XP Prof Windows
Server 2003
Windows ME : Windows2000 Prof, Windows XP Prof Windows
Server 2003
Windows NT (4.0) :Windows2000 Prof, Windows XP Prof Windows
Server 2003, Windows Vista, Windwos7, Windows
Server2008, Red Hat and Other
Windows2000 Prof. : Windows2000 Prof, Windows XP Prof Windows
Server 2003, Windows Vista, Windwos7, Windows
Server2008, Red Hat and Other
Windows XP Prof : Windows2000 Prof, Windows XP Prof Windows
Server 2003, Windows Vista, Windwos7, Windows
Server2008, Red Hat and Other
Windows Server 2003 :Windows2000 Prof, Windows XP Prof Windows
Server 2003, Windows Vista, Windwos7, Windows
Server2008, Red Hat and Other
Windows Vista : Windows Vista, Windwos7, Windows Server2008,
Red Hat and Other
Windwos7 : Windows Vista, Windwos7, Windows Server2008,
Red Hat and Other
Windows Server2008 : Windows Vista, Windwos7, Windows Server2008,
Red Hat and Other
Red Hat and Other : Red Hat
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What can be Upgrade?
Windwos98 : Windows NT (4.0), Windows2000 Prof, Windows
XP Prof
Windows ME :Windows NT (4.0), Windows2000 Prof, Windows
XP Prof
Windows 2000 Prof. : Windows2000 Prof, Windows XP Prof
Windows NT Work (4.0) : Windows2000 Prof, Windows XP Prof
Windows XP Prof : Windows XP Prof
Windows Server 2003 : Windows Server 2003
Windows Vista : Windows Vista, Windwos7
Windwos7 :Windwos7
Windows Server2008 : Windows Server2008
Red Hat : Red Hat
125
M/S and Red Hat Operating System Version List
Red Hat Linux versions
The various Red Hat Linux versions have little different Errata Support Policies
Red Hat Linux 6.2E, 2000-03-27
Red Hat Enterprise Linux 2.1, 26 March 2002
Red Hat Enterprise Linux 2.1 May 2003
Red Hat Enterprise Linux 3, 2003-10-22. (Uses Linux 2.4.21)
Update 1, 16 January 2004
Update 2, 18 May 2004
Update 3, 3 September 2004
Update 4, 21 December 2004
Update 5, 20 May 2005
Update 6, 28 September 2005
Update 7, 15 March 2006
Update 8, 20 July 2006
Update 9, 15 June 2007
Red Hat Enterprise Linux 4, 2005-02-15. (Uses Linux 2.6.9)
4.1, also known as Update 1, 9 June 2005
4.2, also known as Update 2, 5 October 2005
4.3, also known as Update 3, 7 March 2006
4.4, also known as Update 4, 11 August 2006
4.5, also known as Update 5, 1 May 2007
4.6, also known as Update 6, 15 November 2007
4.7, also known as Update 7, 24 July 2008
4.8, also known as Update 8, 18 May 2009
Red Hat Enterprise Linux 5, 2007-03-14. (Uses Linux 2.6.18)
5.1 (also known as Update 1), 2007-11-07
5.2 (also known as Update 2), 2008-05-21
5.3 (also known as Update 3), 2009-01-19
5.4 (also known as Update 4), 2009-09-02
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Microsoft
XENIX (licensed version of UNIX; licensed to SCO in 1987)
MSX-DOS (developed by MS Japan for the MSX 8-bit computer)
MS-DOS (developed jointly with IBM, versions 1.0–6.22)
Windows CE (OS for handhelds, embedded devices, and real-time applications that is
similar to other versions of Windows)
Windows CE 3.0
Windows Mobile (based on Windows CE, but for a smaller form factor)
Windows CE 5.0
Windows CE 6.0
Windows Mobile 5.0
Windows Mobile 6.0
Windows Mobile 6.1
Windows Mobile 6.5
DOS-based Windows
Windows 1.0 (Windows 1)
Windows 2.0 (Windows 2)
Windows 3.0
Windows 3.1x (Windows 3.1)
Windows 3.2 (Chinese-only release)
Windows 9x (Windows 4 Series) family
Windows 95 (Windows 4) (codename: Chicago)
Windows 98 (Windows 4.1) (codename: Memphis)
Windows Millennium Edition (Windows Me - Windows 4.9)
OS/2 (developed jointly with IBM)
Windows NT
Windows NT 3.1 (OS/2 3.0 - Windows 3.1)
Windows NT 3.5 (Windows 3.5)
Windows NT 3.51 (Windows 3.51)
Windows NT 4.0 (Windows 4)
Windows 2000 (Windows NT 5.0 - Windows 5)
Windows XP (Windows NT 5.1 - Windows 5.1) (codename: Whistler)
Windows Server 2003 (Windows NT 5.2 - Windows 5.2) (codename: Whistler Server)
Windows Fundamentals for Legacy PCs
Windows Vista (Windows NT 6.0 - Windows 6) (codename: Longhorn)
Windows Home Server
Windows Server 2008 (Windows NT 6.0 - Windows 6) (codename: Longhorn Server)
Windows 7 (previously codenamed Blackcomb, then Vienna)
Windows Preinstallation Environment (WinPE)
127
What are file systems?
As I wrote in module 4a, drives are storage media, which can hold a file system. When a
disk is formatted in a drive, it becomes organized and prepared to receive data. When we
format a disk, it receives a file system. Formatting can be compared to starting a library.
You must install the book shelves and the catalogue system before any books are put in
place. Once the library is ready, bring on the books! Similarly with a disk. When we
format it; we "burn in" a file system to make it ready to receive data (files). We can
format with any one of several different file systems
FAT (File Allocation Table), the original, old 16 bit DOS system is probably used in
90% of all PC’s. It is also called FAT16
FAT32 a new addition to FAT, which Microsoft introduced with Windows 95 B – The
December -96 versions (OSR2)?
HPFS (High Performance File System) from OS/2. It is an advanced 32 bit file system,
which in all respects is far superior to FAT, except for possible usage. It can only be used
with OS/2.
NTFS from Windows NT. A 32 bit file system like HPFS, but not compatible with it.
NTFS can, unfortunately, only be used in Windows NT. If it was available for use in
Windows 95, it would be far to preferable to FAT and FAT32.
NetWare is a server operating system from Novell. It has its own 32 bit file system.
For that reason, the Novell server, contrary to NT or OS/2 servers, cannot be used as a
work station. The file system is much faster than FAT, but it works only with Novell
servers (typically file servers).
UNIX servers have their own filing system. Here the use of upper/lower case in file
naming is significant. Read in the following pages about the concepts of these file
systems...
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Chapter - 9
Windows shortcut Key
Windows shortcut key
Windows system key combinations
• F1: Help
• CTRL+ESC: Open Start menu
• ALT+TAB: Switch between open programs
• ALT+F4: Quit program
• SHIFT+DELETE: Delete item permanently
Windows program key combinations
• CTRL+C: Copy
•
CTRL+X: Cut
• CTRL+V: Paste
• CTRL+Z: Undo
•
CTRL+B: Bold
• CTRL+U: Underline
• CTRL+I: Italic
Mouse click/keyboard modifier combinations for shell objects
• SHIFT+right click: Displays a shortcut menu containing alternative
commands
• SHIFT+double click: Runs the alternate default command (the second
item on the menu)
• ALT+double click: Displays properties
• SHIFT+DELETE: Deletes an item immediately without placing it in the
Recycle Bin
General keyboard-only commands
• F1: Starts Windows Help
• F10: Activates menu bar options
• SHIFT+F10 Opens a shortcut menu for the selected item (this is the same
129
as right-clicking an object
• CTRL+ESC: Opens the Start menu (use the ARROW keys to select an
item)
• CTRL+ESC or ESC: Selects the Start button (press TAB to select the
taskbar, or press SHIFT+F10 for a context menu)
• ALT+DOWN ARROW: Opens a drop-down list box
• ALT+TAB: Switch to another running program (hold down the ALT key
and then press the TAB key to view the task-switching window)
• SHIFT: Press and hold down the SHIFT key while you insert a CD-ROM
to bypass the automatic-run feature
• ALT+SPACE: Displays the main window's System menu (from the
System menu, you can restore, move, resize, minimize, maximize, or
close the window)
• ALT+- (ALT+hyphen): Displays the Multiple Document Interface (MDI)
child window's System menu (from the MDI child window's System
menu, you can restore, move, resize, minimize, maximize, or close the
child window)
• CTRL+TAB: Switch to the next child window of a Multiple Document
Interface (MDI) program
• ALT+underlined letter in menu: Opens the menu
• ALT+F4: Closes the current window
• CTRL+F4: Closes the current Multiple Document Interface (MDI)
window
• ALT+F6: Switch between multiple windows in the same program (for
example, when the Notepad Find dialog box is displayed, ALT+F6
switches between the Find dialog box and the main Notepad window)
Shell objects and general folder/Windows Explorer shortcuts
For a selected object:
• F2: Rename object
• F3: Find all files
• CTRL+X: Cut
• CTRL+C: Copy
• CTRL+V: Paste
• SHIFT+DELETE: Delete selection immediately, without moving the item
to the Recycle Bin
• ALT+ENTER: Open the properties for the selected object
General folder/shortcut control
• F4: Selects the Go To A Different Folder box and moves down the entries
in the box (if the toolbar is active in Windows Explorer)
• F5: Refreshes the current window.
• F6: Moves among panes in Windows Explorer
130
• CTRL+G: Opens the Go To Folder tool (in Windows 95 Windows
Explorer only)
• CTRL+Z: Undo the last command
• CTRL+A: Select all the items in the current window
• BACKSPACE: Switch to the parent folder
• SHIFT+click+Close button: For folders, close the current folder plus all
parent folders
Windows Explorer tree control
• Numeric Keypad *: Expands everything under the current selection
• Numeric Keypad +: Expands the current selection
• Numeric Keypad -: Collapses the current selection.
• RIGHT ARROW: Expands the current selection if it is not expanded,
otherwise goes to the first child
• LEFT ARROW: Collapses the current selection if it is expanded,
otherwise goes to the parent
Properties control
• CTRL+TAB/CTRL+SHIFT+TAB: Move through the property tabs
Accessibility shortcuts
• Press SHIFT five times: Toggles StickyKeys on and off
• Press down and hold the right SHIFT key for eight seconds: Toggles
FilterKeys on and off
• Press down and hold the NUM LOCK key for five seconds: Toggles
ToggleKeys on and off
• Left ALT+left SHIFT+NUM LOCK: Toggles MouseKeys on and off
• Left ALT+left SHIFT+PRINT SCREEN: Toggles high contrast on and
off
Microsoft Natural Keyboard keys
• Windows Logo: Start menu
• Windows Logo+R: Run dialog box
• Windows Logo+M: Minimize all
• SHIFT+Windows Logo+M: Undo minimize all
• Windows Logo+F1: Help
• Windows Logo+E: Windows Explorer
• Windows Logo+F: Find files or folders
• Windows Logo+D: Minimizes all open windows and displays the desktop
• CTRL+Windows Logo+F: Find computer
• CTRL+Windows Logo+TAB: Moves focus from Start, to the Quick
Launch toolbar, to the system tray (use RIGHT ARROW or LEFT
131
ARROW to move focus to items on the Quick Launch toolbar and the
system tray)cccccc
• Windows Logo+TAB: Cycle through taskbar buttons
• Windows Logo+Break: System Properties dialog box
• Application key: Displays a shortcut menu for the selected item
Microsoft Natural Keyboard with IntelliType software installed
• Windows Logo+L: Log off Windows
• Windows Logo+P: Starts Print Manager
• Windows Logo+C: Opens Control Panel
• Windows Logo+V: Starts Clipboard
• Windows Logo+K: Opens Keyboard Properties dialog box
• Windows Logo+I: Opens Mouse Properties dialog box
• Windows Logo+A: Starts Accessibility Options (if installed)
• Windows Logo+SPACEBAR: Displays the list of Microsoft IntelliType
shortcut keys
• Windows Logo+S: Toggles CAPS LOCK on and off
Dialog box keyboard commands
• TAB: Move to the next control in the dialog box
• SHIFT+TAB: Move to the previous control in the dialog box
• SPACEBAR: If the current control is a button, this clicks the button. If
the current control is a check box, this toggles the check box. If the
current control is an option, this selects the option.
• ENTER: Equivalent to clicking the selected button (the button with the
outline)
• ESC: Equivalent to clicking the Cancel button
• ALT+underlined letter in dialog box item: Move to the corresponding
item
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XP Run Commands
Here is a list of commands you can execute from the Run command prompt in XP:
Accessibility Controls
access.cpl
Add Hardware Wizard
hdwwiz.cpl
Add/Remove Programs
appwiz.cpl
Administrative Tools
certmgr.msc
Character Map
charmap
Check Disk Utility
chkdsk
Clipboard Viewer
clipbrd
Command Prompt
cmd
Component Services
dcomcnfg
Computer Management
compmgmt.msc
Date and Time Properties
timedate.cpl
DDE Shares
ddeshare
Device Manager
devmgmt.msc
Direct X Control Panel (If Installed)
directx.cpl
Direct X Troubleshooter
dxdiag
Disk Cleanup Utility
cleanmgr
Disk Defragment
dfrg.msc
Disk Management
diskmgmt.msc
Disk Partition Manager
diskpart
Display Properties
control desktop
Display Properties
desk.cpl
Display Properties (w/Appearance Tab Preselected)
133
control color
Dr. Watson System Troubleshooting Utility
drwtsn32
Driver Verifier Utility
verifier
Event Viewer
eventvwr.msc
File Signature Verification Tool
sigverif
Findfast
findfast.cpl
Folders Properties
control folders
Fonts
control fonts
Fonts Folder
fonts
Free Cell Card Game
freecell
Game Controllers
joy.cpl
Group Policy Editor (XP Prof)
gpedit.msc
Hearts Card Game
mshearts
Iexpress Wizard
iexpress
Indexing Service
ciadv.msc
Internet Properties
inetcpl.cpl
IP Configuration (Display Connection Configuration)
ipconfig /all
IP Configuration (Display DNS Cache Contents)
ipconfig /displaydns
IP Configuration (Delete DNS Cache Contents)
ipconfig /flushdns
IP Configuration (Release All Connections)
ipconfig /release
IP Configuration (Renew All Connections)
ipconfig /renew
IP Configuration (Refreshes DHCP & Re-Registers DNS)
ipconfig /registerdns
IP Configuration (Display DHCP Class ID)
ipconfig /showclassid
IP Configuration (Modifies DHCP Class ID)
134
ipconfig /setclassid
Java Control Panel (If Installed)
javaws
Keyboard Properties
control keyboard
Local Security Settings
secpol.msc
Local Users and Groups
lusrmgr.msc
Logs You Out Of Windows
logoff
Microsoft Chat
winchat
Minesweeper Game
winmine
Mouse Properties
control mouse
Mouse Properties
main.cpl
Netstat
netstat
Network Connections
control netconnections
Network Connections
ncpa.cpl
Network Setup Wizard
netsetup.cpl
Notepad
notepad
Nview Desktop Manager (If Installed)
nvtuicpl.cpl
Object Packager
packager
ODBC Data Source Administrator
odbccp32.cpl
On Screen Keyboard
osk
Opens AC3 Filter (If Installed)
ac3filter.cpl
Password Properties
password.cpl
Performance Monitor
perfmon.msc
Performance Monitor
perfmon
Phone and Modem Options
135
telephon.cpl
Power Configuration
powercfg.cpl
Printers and Faxes
control printers
Printers Folder
printers
Private Character Editor
eudcedit
Quicktime (If Installed)
QuickTime.cpl
Regional Settings
intl.cpl
Registry Editor
regedit
Remote Desktop
mstsc
Removable Storage
ntmsmgr.msc
Removable Storage Operator Requests
ntmsoprq.msc
Resultant Set of Policy (XP Prof)
rsop.msc
Scanners and Cameras
sticpl.cpl
Scheduled Tasks
control schedtasks
Security Center
wscui.cpl
Services
services.msc
Shared Folders
fsmgmt.msc
Shuts Down Windows
shutdown
Sounds and Audio
mmsys.cpl
Spider Solitare Card Game
spider
SQL Client Configuration
cliconfg
System Configuration Editor
sysedit
System Configuration Utility
msconfig
System File Checker Utility (Scan Immediately)
136
sfc /scannow
System File Checker Utility (Scan Once At Next Boot)
sfc /scanonce
System File Checker Utility (Scan On Every Boot)
sfc /scanboot
System File Checker Utility (Return to Default Setting)
sfc /revert
System File Checker Utility (Purge File Cache)
sfc /purgecache
System File Checker Utility (Set Cache Size to size x)
sfc /cachesize=x
System Properties
sysdm.cpl
Task Manager
taskmgr
Telnet Client
telnet
Traceroute
tracert <hostname or IP>
User Account Management
nusrmgr.cpl
Utility Manager
utilman
Windows Firewall
firewall.cpl
Windows Magnifier
magnify
Windows Management Infrastructure
wmimgmt.msc
Windows System Security Tool
syskey
Windows Update Launches
wupdmgr
Windows XP Tour Wizard
tourstart
Wordpad
Write
Calc - Calculator
Cfgwiz32 - ISDN Configuration Wizard
Charmap - Character Map
Chkdisk - Repair damaged files
Cleanmgr - Cleans up hard drives
Clipbrd - Windows Clipboard viewer
Cmd - Opens a new Command Window (cmd.exe)
Control - Displays Control Panel
Dcomcnfg - DCOM user security
137
Debug - Assembly language programming tool
Defrag - Defragmentation tool
Drwatson - Records programs crash & snapshots
Dxdiag - DirectX Diagnostic Utility
Explorer - Windows Explorer
Fontview - Graphical font viewer
Ftp - ftp.exe program
Hostname - Returns Computer's name
Ipconfig - Displays IP configuration for all network adapters
Jview - Microsoft Command-line Loader for Java classes
MMC - Microsoft Management Console
Msconfig - Configuration to edit startup files
Msinfo32 - Microsoft System Information Utility
Nbtstat - Displays stats and current connections using NetBios over TCP/IP
Netstat - Displays all active network connections
Nslookup- Returns your local DNS server
Ping - Sends data to a specified host/IP
Regedit - egistry Editor
Regsvr32 - egister/de-register DLL/OCX/ActiveX
Regwiz - Reistration wizard
Sfc /scannow - Sytem File Checker
Sndrec32 - Sound Recorder
Sndvol32 - Volume control for soundcard
Sysedit - Edit system startup files (config.sys, autoexec.bat, win.ini, etc.)
Taskmgr - Task manager
Telnet - Telnet program
Tracert - Traces and displays all paths required to reach an internet host
Winipcfg - Displays IP configuration
Management Consoles
certmgr.msc - Certificate Manager
ciadv.msc - Indexing Service
compmgmt.msc - Computer management
devmgmt.msc - Device Manager
dfrg.msc - Defragment
diskmgmt.msc - Disk Management
fsmgmt.msc - Folder Sharing Management
eventvwr.msc - Event Viewer
gpedit.msc - Group Policy -XP Pro only
iis.msc - Internet Information Services
lusrmgr.msc - Local Users and Groups
mscorcfg.msc - Net configurations
ntmsmgr.msc - Removable Storage
perfmon.msc - Performance Manager
secpol.msc - Local Security Policy
services.msc - System Services
wmimgmt.msc - Windows Management
138
access.cpl - Accessibility Options
hdwwiz.cpl - Add New Hardware Wizard
appwiz.cpl - dd/Remove Programs
timedate.cpl - Date and Time Properties
desk.cpl - Display Properties
inetcpl.cpl - Internet Properties
joy.cpl - Joystick Properties
main.cpl keboard - Keyboard Properties
main.cpl - Mouse Properties
ncpa.cpl - Network Connections
ncpl.cpl - Network Properties
telephon.cpl - Phone and Modem options
powercfg.cpl - Power Management
intl.cpl - Regional settings
mmsys.cpl sounds - Sound Properties
mmsys.cpl - Sounds and Audio Device Properties
sysdm.cpl - System Properties
nusrmgr.cpl - User settings
firewall.cpl - Firewall Settings (sp2)
wscui.cpl - Security Center (sp2)
WRITE -WordPad.
WSCRIPT -Script Hosting Settings.
WUPDMGR -Windows Update Manager.
WMIMGMT.MSC -Windows Management Infrastructure.
WINVER -Tells About Windows License And a Little System Information.
WINMSD -System Information.
MSINFO32 -Detailed System Information.
WINMINE -Mine Game.
WINHLP32 -Opens Help File Of Specified Program.
WINCHAT -Chat With Other Computer On Internet Or LAN. WIAACMGR -Camera
And Scanner Utility.
VERIFIER -Driver Verification Utility (Not turned off automatically).
VERIFIER /RESET -Ends Driver Verification.
UTILMAN -Utility Manager.
USERINIT -Opens Folder Tab Under ‘My Document’.
TSSHUTDN -System Shut Down (in 60 sec.) Utility.
TSDISCON -Exits (Not Logs Off) Current User.
TOURSTART -Xp Tour.
TLNTSVR -Starts Telnet Server.
TCMSETUP -Telephone Client Help.
TASKMGR -Task Manager.
SYSKEY -XP Account Database Additional Encryption. SSMYPICS.SCR -Screen Saver
With ‘My Picture’ Folder.
SPIDER -Spider Solitaire Game.
SOL -Solitaire Game.
SNDVOL32 -Volume Control.
139
SNDREC32 -Sound Recording Utility.
SIGVERIF -File Signature Verification.
SHRPUBW -Shared Folder Creation Wizard.
SERVICES.MSC -Services’ Utility.
SECPOL.MSC -Local Security Setting.
SECEDIT -Security Configuration Management Help File. SC -CMD Program To
Communicate With NT Service Controller.
RUNDLL32 -Start Specified DLL.
NETSHARE -Sharing Session.
RSOP.MSC -Resultant Set Of Policy.
REGEDIT -Registry Editor.
RASPHONE -Network Connection.
PERFMON -Enhanced Performance Monitor.
PACKAGER -Object Packager.
OSK -On Screen Keyboard.
ODBCAD32 -ODBC Data Source Management.
NTMSOPRQ.MSC -Removal Storage Operator Request Management. NTMSMGR.MSC
-Removal Storage Management.
NTBACKUP -Backup Utility.
NOTEPAD -Notepad.
NSLOOKUP -Default Server Information.
NETSETUP -Network Setup Wizard.
MSTSC -Remote Desktop Connection.
MSPAINT -Microsoft Paint.
MSHEARTS -Hearts Game.
MPLAY32 -Media Player And Editor.
MOBSYNC -Synchronizing Tool.
MMC -Microsoft Management Console.
MAGNIFY -Magnifier.
LUSRMGR.MSC -Local User And Group Management.
LOGOFF -Log Off.
LABEL X: -Create label For X Drive.
IEXPRESS -Iexpress Wizard.
GPEDIT.MSC -Group Policy Editor.
FTP -CMD FTP Client.
FSQUIRT -Bluetooth File Transfer Wizard.
FSMGMT -Shared Folder Management.
FREECELL -FreeCell Game.
EVENTVMR -Event Viewer.
EUDCEDIT -Private Character Editor.
DXDIAG -DirectX Diagnosis Tool.
DVDPLAY -Open WMP For DVD Playback.
DRWTSN32 -Dr. Watson.
DISKMGMT.MSC -Disk Management Service.
DFRG.MSC -Disk Defragmenter.
DEVMGMT.MSC -Device Management.
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DCOMCNFG -Component Services.
CONTROL -Control Panel.
COMPMGMT.MSC -Component Management.
COMP -File Comparison.
CMD -Command Prompt.
CLIPBRD -Clipboard Viewer.
CLICONFG -SQL Server Client Network Utility.
CLEANMGR -Disk Cleaner.
CLEANMGR /SAGESET:99 -Automatic Disk Cleanup Utility.
CIADV.MSC -Indexing Service.
CHKDSK X: -Disk Checking Utility For Drive X.
CHARMAP -Character Map.
CERTMGR.MSC -File Certificate Manger.
CALC -Calculator.
ACCWIZ -Accessibility Wizard.
ACCESS.CPL -Accessibility Option.
APPWIZ.CPL -Add/Remove Program Utility.
DESK.CPL -Desktop Property.
FIREWALL.CPL -Firewall Setting.
HDWWIZ.CPL -Add Hardware wizard.
INETCPL.CPL -Internet Property.
INTL.CPL -Region And Language Setting.
JOY.CPL -Game Controller Setup.
MAIN.CPL -Mouse Property.
MMSYS.CPL -Sound Property.
NCPA.CPL -View Network Connection.
NETSETUP.CPL -Network Setup Wizard.
NUSRMGR.CPL -Account Management.
ODBCCP32.CPL -ODBC Data Source Administrator.
JPICPL32.CPL -JAVA Plug-in Control Panel.
POWERCFG.CPL -Power Option.
SYSDM.CPL -System Property.
TELEPHON.CPL -Phone And Modem Property.
TIMEDATE.CPL -Date And Time Property.
WSCUI.CPL -Windows Security Center.
WUACPL.CPL -Automatic Update Setting.
Windows Environment Commands
%ALLUSERSPROFILE% - Open the All User's Profile
%HomeDrive% - Opens your home drive e.g. C:\
%UserProfile% - Opens you User's Profile
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%temp% Opens - temporary file Folder
%systemroot% - Opens Windows folder
Wupdmgr - Takes you to Microsoft Windows Update
Dsa.msc – a.d open
RECENT – OPEN RECENT ITEM
\documents and settings
\program files
\windows
\wmpub
Msmgs =window messenger
Dnsmgmt.msc
Dhcpmgmt.msc
Systeminfo
Rrasmgmgt.msc
Dcpromo /force removal
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Chapter-10
Some Sort Form
Accelerated Graphics Port (AGP) A bus developed to meet the need for increased
graphics performance.
Active partition the partition from which an operating system boots. Adapter card a
daughter card that extends the capabilities of the motherboard.
Advanced Configuration and Power Interface (ACPI) a standard that defines common
interfaces for hardware recognition and configuration, and more importantly, power
management.
Answer file in an unattended installation, this file contains all of the correct parameters
(time zone, regional settings, administrator user name, and so on), needed for installation.
AppleTalk A proprietary network protocol for Macintosh computers.
AT system connector the power-supply connector pair for the AT motherboard often
marked P8 and P9 that was used in the original IBM PC but is now associated by name
with the PC/AT.
Attended installation an installation where a user is required to provide answers to
options during the installation process.
ATX motherboard a smaller successor to the AT motherboard that uses space more
wisely and places related components closer together.
ATX system connector the single, larger power-supply connector that powers the ATX
motherboard.
Authentication A process that proves that a user or system is actually who they say they
are.
Automated System Recovery (ASR) ASR first creates a backup of your system partition
And then creates a recovery disk. Using these two components, you can recover from a
system crash and restore the system to a functional state.
Autorun When a compact disc automatically begins its program when it’s inserted into
the computer.
Baby AT A form factor that denotes AT compatibility but in a smaller size. Backside
bus a set of signal pathways between the CPU and Level 2 cache memory. Backup A
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copy of files stored in a location other than where they originally came from. Backlight
A small fluorescent lamp placed behind, above, or to the side of an LCD display.
Berg connectors the official name for the smaller peripheral power-supply connectors
that most often attach to floppy disk drives.
Bidirectional A satellite connection wherein the satellite is used for both uploads and
downloads.
Blue screen of death (BSOD) the blue-screen error condition that occurs when Windows
2000/XP fails to boot properly or quits unexpectedly.
Bluetooth A popular standard for wireless communication.
Bluetooth Special Interest Group (SIG) The consortium of companies that developed the
Bluetooth technology.
BNC A type of connector used to attach stations to a Thinnet network.
Bonding Combining two bearer channels into one 128Kbps data connection to
maximize throughput.
Boot logging Logs all boot information to a file called NTBTLOG.TXT. You can then
check the log for assistance in diagnosing system startup problems.
Boot ROM A piece of hardware (often built into a network card) that is capable of
downloading a small file that contains enough information to boot the computer and
attach it to the network.
Broadband The general designation for higher-speed Internet connections. Broadcast
To send a signal to all entities that can listen to it. In networking, it refers to
Sending a signal to all entities connected to that network.
Bubble-jet printer a type of sprayed-ink printer. It uses an electric signal that energizes a
heating element, causing ink to vaporize and be pushed out of the pinhole and onto the
paper.
Carriage belt the printer belt placed around two small wheels or pulleys and attached to
the print head carriage. The carriage belt is driven by the carriage motor and moves the
print head back and forth across the page during printing.
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Carriage motor a stepper motor used to move the print head back and forth on a dotmatrix
printer.
Carriage stepper motor the printer motor that makes the print head carriage move.
Case The external container for the system.
Case frame the metal reinforcing structure inside the laptop that provides rigidity and
strength and that most components mount to.
Cell A cellular phone network. Central processing unit (CPU) the microprocessor chips
that gives a computer its fundamental characteristics.
Centralized processing a network processing scheme in which all “intelligence” is found
in one computer and all other computers send requests to the central computer to be
processed. Mainframe networks use centralized processing.
Certificates A common form of authentication.
Charge coupled device (CCD) array a matrix of photosensitive capacitors arranged so
that one capacitor charges its neighbor, resulting in a representative sample for a row of
capacitors. CCD arrays are used as photoreceptors in scanners and digital photographic
equipment.
Charging corona the wire or roller that is used to put a uniform charge on the EP drum
Inside a toner cartridge.
Charging step the step in EP printing at which a special wire in the toner cartridge gets a
High voltage from the HVPS. It uses this high voltage to apply a strong, uniform negative
charge (around -600VDC) to the surface of the photosensitive drum.
Chipset A small group of larger chips that takes the place of a large number of earlier
chips to perform a similar function.
Clamshell designs a popular design for laptops.
Cleaning cycle a set of steps the bubble-jet printer goes through in order to purge the
print heads of any dried ink.
Cleaning step the step in the EP print process at which excess toner is scraped from the
EP drum with a rubber blade.
Client computer a computer that requests resources from a network. Client software
that allows a device to request resources from a network.
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CMOS battery the battery that maintains without external power the contents of the
special memory chip that holds the alterations made to the BIOS settings.
Coaxial cable a medium for connecting computer components that contains a center
conductor, made of copper, surrounded by a plastic jacket, with a braided shield over the
jacket.
Collision light The LED on a network device that indicates the detection of a collision.
Communication network riser (CNR) Sixty-pin slots found on some Intel motherboards
that are a replacement for AMR slots. Using CNR slots, a motherboard manufacturer can
implement a motherboard with certain integrated features and leave room for future
expansion.
Compact disc-recordable (CD-R) and compact disc-rewritable (CD-RW) drives
Compact
Disc drives with the capability to “burn” contents to specially manufactured discs.
Compact installation Also known as a minimal installation, it installs only the files
necessary to run Windows.
Compression a feature in Windows 2000 and XP that gives you the option of
compressing existing files in a particular folder. If the feature is turned on, Windows
2000 and XP automatically compress the subfolders and files. If not, only new files
created in the directory are compressed.
Computer name the name by which a computer will be known if it participates on a
Network.
Connectivity device any device that facilitates connections between network devices.
Some examples include hubs, routers, switches, and gateways.
Corona roller a type of transfer corona assembly that uses a charged roller to apply
charge to the paper.
Corona wires a type of transfer corona assembly. Also, the wire in that assembly that is
Charged by the high-voltage supply. It is narrow in diameter and located in a special
notch under the EP print cartridge.
Custom installation an installation method where the user gets to choose which
components are installed.
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Daisy-wheel printer an impact printer that uses a plastic or metal print mechanism with
a different character on the end of each spoke of the wheel. As the print mechanism
rotates to the correct letter, a small hammer strikes the character against the ribbon,
transferring the image onto the paper.
Daughterboard Any circuit board connected to the motherboard. DC adapter the
adapter which provides DC current to the laptop.
Dedicated server the server that is assigned to perform a specific application or service.
Decrementing Reorganizing files on a hard disk so they are in consecutive order.
Delay An impedance to the flow of a signal that causes the moment of transmission by
the source to be earlier than the moment of receipt by the destination.
Denial of Service (DoS) attacks that prevent access to resources by users authorized to
use those resources.
Developing roller the roller inside a toner cartridge that presents a uniform line of toner
to help apply the toner to the image written on the EP drum. Developing step the step in
the EP print process at which the image written on the EP drum by the laser is
developed—that is, it has toner stuck to it.
Device driver a software file that allows an operating system to communicate with a
hardware device. Also called a driver.
Digitally signed driver a driver that has been digitally “signed” by Microsoft with a
special value that only Windows can read. This signature tells the Windows installer that
the driver being installed has been tested for security and stability on the chosen
Windows platform and that the driver is from a reputable source.
Direct-solder method a method of connecting a peripheral port by directly soldering
individual ports to the motherboard. This method is used mostly in integrated
motherboards in non-clone machines.
Disk cache a small amount of memory that is used to hold data that is frequently
accessed from the hard disk.
Diskette One of variously sized magnetic-coated Mylar disks packaged in a square
protective cover.
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Distributed processing a computer system in which processing is performed by several
separate computers linked by a communications network. The term often refers to any
computer system supported by a network, but more properly refers to a system in which
each computer is chosen to handle a specific workload and the network supports the
system as a whole.
DIX Ethernet the original name for the Ethernet network technology. Named after the
original developer companies: Digital, Intel, and Xerox.
Docking port a port used to connect the laptop to a special laptop. Docking station and
extension of the motherboard of a laptop.
Dot-matrix printer impact printers that have a print head containing a row of pins (short,
sturdy stalks of hard wire) that are used to strike the ink ribbon to create an image.
Dot phosphor the phosphorescent chemical dots that coat the back of a CRT monitor’s
Screen. Electron beams excite these dots and cause them to glow.
Dot pitches the average measurement between two dot phosphors on a CRT screen. The
smaller the dot pitch, the better the picture quality.
Drive interfaces the connectors and related technology used to attach drives and similar
devices to adapters or the motherboard. Examples include ATA, SCSI, and ESDI.
Driver A software file that allows an operating system to communicate with a hardware
device. Also called a device driver.
Dual-boot configuration a computer that has more than one operating system installed.
During boot, the user can choose which operating system to start.
Dual Inline Memory Modules (DIMMs) Memory sticks that install in slots on
motherboards and specialty devices to act as primary memory in service of the CPU.
DIMMs are so named for the fact that the pins on each side of the module are
independent of one another. Contrast with Single Inline Memory Modules (SIMMs).
Electron gun the devices that shoot a beam of electrons at the back of a CRT screen to
illuminate the dot phosphors, thus producing an image on the front of the screen.
Electromagnetic interference (EMI) any electromagnetic radiation released by an
electronic device that disrupts the operation or performance of any other device.
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Electronic stepper motor a special electric motor in a printer that can accurately move in
Very small increments. It powers all of the paper transport rollers as well as the fuser
rollers.
Emergency repair disk (ERD) a disk that contains backup copies of portions of your
Registry. It can be used to recover the system in the event of an operating system failure.
Ethernet A network technology based on the IEEE 802.3 CSMA/CD standard. The
original Ethernet implementation specified 10MBps, baseband signaling, coaxial cable,
and CSMA/CD media access.
Ethernet port A LAN interface that follows the Ethernet standard. Ethernet ports can be
the most popular eight-pin modular connector, referred to as an RJ-45, or it can be a fiber
or coaxial interface. The Ethernet port is found on the NIC in a computer system.
Expansion cards a daughter card that expands the capabilities of a motherboard. Also
known as an adapter card.
Expansion slots on a motherboard to receive expansion cards. Expansion cards and slots
must be of the same type, PCI, Pie, or AGP, for example.
Extended Graphics Array (XGA) Introduced in 1990 by IBM, this is often thought of as
a synonym for the 1024 × 768.
Fax modem an adapter that fits into a PC expansion slot and provides many of the
capabilities of a full-sized fax machine, but at a fraction of the cost.
Feed roller the rubber roller in a laser printer that feeds the paper into the printer. Feeder
A device that feeds paper or other media into a printer.
File Allocation Table (FAT) 16 an acronym for the file on this file system used to keep
track of where files are. Many OS s have built their filesystem on the design of FAT, but
without its limitations. A FAT file system uses the 8.3 naming convention (eight letters
for the name, a period, and then a three-letter file identifier). This later became known as
FAT16 (to differentiate it from FAT32) because it used a 16-bit binary number to hold
cluster-numbering information. Because of that number, the largest FAT disk partition
that could be created was approximately 2GB.
File locking a feature of many network operating systems that “locks” a file to prevent
more than one person from updating the file at the same time.
File permissions These serve the purpose of controlling who has access and what type of
access to what files or objects they have.
Files and Settings Transfer Wizard A Windows XP utility that transfers files and
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individual application settings from an old computer to a new one.
finisher A device on a printer that performs such final functions as folding, stapling,
hole punching, sorting, or collating the documents being printed.
FireWire A trade name for IEEE 1394, FireWire is a competing standard of USB.
Firmware Software encoded on hardware. The BIOS routine and its chip is an example
of firmware.
Flatbed scanner an optical device that can be used to digitize a whole page or a large
image. Floppy disk See diskette.
Floppy drive the hardware device that reads and writes to a floppy disk.
Floppy drive interfaces the drive interface for the floppy subsystem, which consists of
34 pins and is not compatible with the various hard drive interfaces.
Floppy drive power connectors See Berg connectors.
Font the typestyle used for printing a document. The font can be loaded onto the hard
drive of the computer or the onboard memory of the printer.
Format to prepare a volume to receive files and folders by defining the file structure
formatting The process of preparing the partition to store data in a particular fashion.
Frame The Data Link layer product that includes a portion of the original user data,
upper layer headers, and the Data Link header and trailer.
Front side bus a set of signal pathways between the CPU and main memory. full AT
The original AT form factor, which was followed by the baby AT form factor. Fullduplex
communication Communications where both entities can send and receive
Simultaneously.
Full installation an installation method that installs every component, even those that
may not be required or used frequently.
Fuser A device on an EP printer that uses two rollers to heat the toner particles and melt
them to the paper. The fuser is made up of a halogen heating lamp, a Teflon-coated
aluminum fusing roller, and a rubberized pressure roller. The lamp heats the aluminum
roller. As the paper passes between the two rollers, the rubber roller presses the paper
against the heated roller. This causes the toner to melt and become a permanent image on
the paper.
Fusing step the step in the EP printing process during which the toner image on the paper
is fused to the paper using heat and pressure. The heat melts the toner, and the
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pressure helps fuse the image permanently to the paper.
Game port A DA15F interface designed for joysticks and other game controllers.
Global System for Mobile Communications (GSM) The most popular cellular standard.
It uses a variety of bands to transmit. The most popular are 900 MHz and 1800 MHz, but
400, 450, and 850 MHz are also used.
graphics mode As opposed to text mode, graphics mode displays shapes and images not
Based on text characters.
Handheld scanner a type of scanner that is small enough to be held in your hand. Used
to digitize a relatively small image or artwork, it consists of the controller, CCD, and
light source contained in a small enclosure with wheels on it.
Hardening The process of reducing or eliminating weaknesses, securing services, and
attempting to make your environment immune to attacks.
Hardware Compatibility List (HCL) A list of all the hardware that works with Windows
and which versions of Windows it works with.
Header Information attached to the beginning of a network data frame. Heat spreaders
Metal covers for memory modules that act as heat sinks. Hermaphroditic data connector
a connector that is both male and female. Hibernation A state that laptops are capable of
entering in.
High-voltage probe a tool with a very large needle, a gauge that indicates volts, and a
wire with an alligator clip used to discharge electricity from electronic devices.
Home computer In Remote Desktop, the home computer is the one you are sitting at,
and
The computer that makes the connection to the remote computer.
I/O memory Standard memory locations attributed to devices connected through
expansion buses and accessed by the I/O signal of the I/O_MEM line from the processor
to the memory controller
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Image An exact replica of an installed computer, used to install an operating system on
other computers.
Impact printers any printer that forms an image on paper by forcing a character image
against an inked ribbon. Dot-matrix, daisy-wheel, and line printers are all impact printers,
whereas laser printers are not.
Industry Standard Architecture (ISA) expansion slot an old, nearly obsolete type of
Expansion slot in a motherboard.
Infrared Data Association (IrDA) standard a personal area network (PAN) standard for
The exchange of data over short distances using infrared light.
Infrared port A serial port that uses line-of-sight to attach to another infrared port for the
Exchange of data using IrDA.
Infrared transmissions Wireless transmission between devices that use radiation in the
infrared range of the electromagnetic spectrum.
Ink cartridge a reservoir of ink and a print head, in a removable package. Inoculating
Making the computer resistant to computer viruses.
Integrated system board a motherboard with components built in, reducing the need for
a large number of expansion cards.
Interface The port or connection through which a device attaches to an external
component, such as a printer’s parallel or USB port for connection to a computer, as well
as the software that enables the port to communicate with the external component, such
as a Windows XP driver for an HP LaserJet.
Interface circuitry that converts the signals from the interface into the DataStream that
the printer or other device uses.
Interface software the operating system-specific driver that enable communication
between the computer and a peripheral.
Interlaced A video standard that scans alternate lines on the monitor with each pass,
effectively halving the nominal refresh rate. Contrast with progressive.
Internet service providers (ISP) a company that provides Internet access and e-mail
Addresses for users. Generally, ISPs are local or regional companies.
Internet work Any TCP/IP network that spans router interfaces. Anything from a small
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office with two subnets to the Internet itself can be described as an internet work.
Internetwork Packet Exchange/Sequenced Packet Exchange (IPX/SPX) the default
communication protocol for versions of the Novell NetWare operating system before
NetWare 5. IPX and SPX correspond loosely to IP and TCP, respectively, in the TCP/IP
protocol suite.
Keyboard/mouse port the port that the keyboard or mouse connects to. Laser printer a
generic name for a printer that uses the electro photographic (EP) print process.
Last Known Good Configuration An advanced boot option that lets you restore the
system to a prior, functional state, which will allow you to log in again.
Letter quality (LQ) a category of dot-matrix printer that can print characters that look
very close to the quality a laser printer might produce.
Liquid cooling the use of a circulating liquid, such as water, to dissipate heat.
Logical topology the topology that defines how the data flows in a network. MAC
addresses the unique physical address for each NIC.
Main motor a printer stepper motor that is used to advance the paper.
Maintenance station Provides a zero position for the an ink- or bubble-jet print head and
Keeps the print nozzles clear between print jobs.
Master computer in sysprep, the master computer is the one that is used to make an
image.
Material Safety Data Sheet (MSDS) A document that contains safety information about
a given product. Information provided includes safe handling procedures, what to do in
case of an accident, and disposal information.
MicroDIMM A 45.5mm × 30mm memory module that is over 50 percent smaller than a
SoDIMM. MicroDIMMs were designed for ultra light and portable sub notebook
computers and have 144 or 172 pins.
Minimal installation also known as a compact installation, it installs only the files
necessary to run Windows.
Mini PCI An adaptation of the Peripheral Component Interconnect (PCI) standard used
in desktop computers designed primarily for laptops.
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Modem A concatenation of modulator/demodulator. Modems allow the transmission of
a digital bit stream over an analog medium, such as a standard phone line.
Molex connector the larger peripheral power connector used on such devices as hard
drives and CD/DVD drives.
Monochrome Using a single color to display text and graphics on a screen with a
contrasting background.
Motherboard The main system board of a computer. Daughterboards interface with the
motherboard to expand its capabilities.
Multifunction printers a peripheral that is essentially a printer, copier, scanner, and fax
machine all in one.
Multiplexer A network device that combines multiple data streams into a single stream
for transmission. Multiplexers can also break out the original data streams from a single,
multiplexed stream.
Multipurpose server a server that has more than one use. For example, a multipurpose
Server can be both a file server and a print server.
Nonintegrated system board a motherboard that does not have peripheral interfaces,
Other than keyboard and mouse, permanently attached. These features must come from
expansion cards.
Northbridge A portion of a motherboard’s overall chipset that is responsible for
communications with integrated video and between the processor and memory.
Null modem serial cable a serial cable that crosses signal lines so that a modem is not
necessary to connect two computers directly.
Paper tray the tray that holds paper until it is fed into a printer.
Paper pickup roller A D-shaped roller that rotates against the paper and pushes one sheet
into a printer.
Parallel port a peripheral port that is used most often for printer connection and that
transfers data in parallel instead of one bit at a time.
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Parked When the print head is in the locked, resting position.
Partition A logical grouping of data organized to fall under a single drive letter for
primary partitions and multiple drives for extended partitions
Partitioning The process of assigning part or all of a hard drive for use by the computer.
Passive hub a type of hub that electrically connects all network ports together. This type
of hub is not powered.
PCI Express (PCIe) a more advanced expansion-bus standard to compete with AGP that
is backward compatible with PCI.
Peripheral Component Interconnect (PCI) Today’s most popular expansion-bus
standard.
Peripheral interface any port that allows external devices to connect to the computer
system.
Personal computer (PC) any of a class of computer systems that allows a single user to
perform day-to-day personal and business functions, such as word processing and
networking. Also IBM’s original product name for such a computer system.
Pickup rollers See paper pickup roller.
Pickup stepper motor the motor that turns the pickup roller in a printer.
Piconet A Bluetooth network. A Bluetooth-enabled device can communicate with up to
seven other devices in one piconet.
Pins The minute projections that terminate signal lines and, for example, appear on a
male connector at the end of a cable.
Pixels Short for picture elements, pixels are the individual dots that the software
projecting the image is capable of controlling. Viewable screen sizes, such as 1024 × 768,
refer to the number of pixels in a matrix. Contrast with dot phosphors.
Planar board a synonym for motherboard that generally has no processor but instead has
a modular interface for a processor card.
Plenum-rated When referring to coaxial covering, a designation that means the coating
does not produce toxic gas when burned (as PVC does) and is rated for use in air plenums
that carry breathable air.
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Plug and Play BIOS A BIOS that communicates with Plug and Play components to
adapt to their existence without the installation of device drivers
Plug and Play (PnP) a standard set of specifications that were developed by Intel to
enable a computer to detect a new device automatically and install the appropriate driver.
Port See interface.
Portable installation A Windows installation method that installs components needed for
Portable system installations on laptops. It includes such features as power management
and LCD display software.
POTS line A Plain Old Telephone Service line, the original analog technology for phone
lines still in use today for standard phone service.
Power circuits the set of conductive pathways that converts 110V or 220V house current
into the voltages a bubble-jet printer uses (usually 12V and 5V) and distributes those
voltages to the other printer circuits and devices that need it.
Power supply the component that converts AC wall voltages to DC voltages that other
Computer components require. Rated in watts, the power supply must be able to handle
the demand placed on it by these components.
Primary partition the first partition created in an operating system. Primary Rate
Interface (PRI) An ISDN interface known as 23B+D, which means it has
23 B channels and one D channel.
Print buffer a small amount of memory located on the printer used to hold print jobs.
Print consumables Products a printer uses in the print process that must be replaced
occasionally. Examples include toner, ink, ribbons, and paper.
Print media another name for the media being printed on. Examples include paper,
transparencies, and labels.
Printer control circuits Runs a printer’s stepper motors, loads paper, and so on. Monitors
the health of the printer and reports that information back to the computer.
Printer controller assembly a large circuit board in a laser printer that converts signals
from the computer into signals for the various parts in a printer.
Printer-resident fonts that is stored locally in the printer’s onboard memory to speed up
printing.
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Printer ribbon a fabric strip that is impregnated with ink and wrapped around two spools
encased in a cartridge. This cartridge is used in dot-matrix printers to provide the ink for
the print process.
Print heads the part of a printer that creates the printed image. In a dot-matrix printer,
the print head contains the small pins that strike the ribbon to create the image, and in an
ink-jet printer, the print head contains the jets used to create the ink droplets as well as
the ink reservoirs. A laser printer creates images using an electro photographic method
similar to that found in photocopiers and does not have a print head.
Print head alignment the process by which the print head is calibrated for use. A special
utility that comes with the printer software is used to do this.
Print head carriage the component of a bubble-jet printer that moves back and forth
during printing. It contains the physical as well as electronic connections for the print
head and (in some cases) the ink reservoir.
Product activation the process of registering your Windows product with Microsoft to
Ensure you have a licensed copy.
Product key a unique key that you enter into Windows during installation to signal that
you have a licensed copy of the software.
PS/2 ports a mini-DIN connector that is used to connect keyboards and mice, so named
for the IBM Personal System/2, where it was originally seen.
Random access memory (RAM) Memory, usually in chip form, that can be read from or
written to in any order
Resource Anything on a network that clients might want to access or use.
Rasterizing The process of converting signals from the computer into signals for the
various assemblies in a laser printer.
Recovery CD A CD-ROM that comes with a particular model and brand of computer
and
Usually contains an image of the entire Windows installation, along with applications,
utilities, and drivers specifically for that computer. Also called a restoration CD.
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Recovery partition a section of hard drive space, usually on a server, that contains an
exact image of a computer’s files and configuration.
Refresh rate the number of times per second, measured in hertz (Hz), that an electron
gun retraces the image on a screen. Higher refresh rates produce better images to the
human eye. Lower refresh rates can cause headaches and poor-quality images.
Registered jack (RJ) a series of modular jacks usually modified by a numerical dentifier,
Such as RJ-11, which identifies the characteristics of that particular registered jack.
Resolution The number of dots in a square inch used to represent the image to be
scanned or printed. Resolution is measured based on a grid of dots in the horizontal and
vertical planes. For example, a resolution of 600 × 600 dpi indicates the device uses
360,000 dots to represent each square inch of the image.
Restoration CD A CD-ROM that comes with a particular model and brand of computer
and that usually contains an image of the entire Windows installation, along with
applications, utilities, and drivers specifically for that computer. Also called a recovery
CD.
Restore point a copy of your system configuration at a given point in time. Ribbon
cartridge the container that holds the printer ribbon. RIMM The module used to carry
Rambus DRAM. RIMM slot the motherboard slot designed to receive a RIMM.
Riser card a card that has no functional circuitry of its own but that provides connecting
Points for other cards parallel to the motherboard.
safe mode Starts Windows 2000/XP using only basic files and drivers, such as mouse
(except serial mice), monitor, keyboard, mass storage, base video, and default system
services.
Scanner An optical device used to digitize images such as line art or photographs, so
that they can be merged with text by a page-layout or desktop publishing program or
incorporated into a CAD drawing.
Serial communications the transmission of information from computer to computer or
From computer to a peripheral, one bit at a time. Serial communications can be
synchronous and controlled by a clock or asynchronous and coordinated by start and stop
bits embedded in the data stream...
Serial ports Interfaces that connect peripheral components using a serial
communications
Stream. Also a specific term for the ANSI/EIA/TIA-232 ports (formerly RS-232) on a
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PC.
Service packs Major patches or upgrades to the Windows operating system are released
in groups known as service packs.
Single Inline Memory Modules (SIMMs) Memory modules that have mated pins in the
same
Position on each side of the module, each pair performing the same function so that the
module’s pin count considers each pair to be only one pin. Contrast to DIMMs, where
each pin in the pair performs a potentially separate function.
Small Outline DIMM (SoDIMM) A smaller form-factor memory module that is used in
smaller systems, such as laptops. Only MicroDIMMs are currently smaller.
Solid-ink printers a printer that uses ink is in a waxy solid form, rather than in liquid
form. This allows the ink to stay fresh and eliminates problems like spillage.
Southbridge A portion of a motherboard’s overall chipset that is responsible for control
of non-AGP video and other I/O communications, such as serial, parallel, and USB ports.
Standard serial cable a serial cable that is used to connect the serial port of a computer
To that of a modem. The signal lines run straight through a standard cable. Contrast to
null modem serial cable.
Stepper motor a very precise motor that can move in very small increments. Often used
In printers.
Super Video Graphics Array (SVGA) port A DE15F interface that has the capability of
Accepting a wide variety of signals using various screen resolutions.
Swap file also called the page file; the swap file is the virtual memory in Windows.
Switch A Layer 2 device similar to a hub in its port count but more advanced with the
ability to filter traffic based on the destination MAC address of each frame.
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Syntax The specific structure required by a text-based command to work properly.
Sysprep A utility used to make an image of a computer for installation on other
computers. System board See motherboard.
System memory the primary computer memory that holds instructions and data for
currently executing software
Temporary file (temp file) a file designed to store information for a short period of time
and then be deleted.
Temporary Internet Files A directory on your hard drive where Internet Explorer copies
any images or HTML files from websites you visit frequently. Used to speed up Internet
access.
Text-based commands that are executed from the command prompt, such as
DIR, CD, or FORMAT.
Text mode As opposed to graphics mode, text mode displays only alphanumeric
characters on the screen, not graphical images.
Thermal printer a non impact printer that uses a thermal print head and specially treated
paper to create an image.
Thrashing When you have an extremely slow system and a disk that is constantly being
accessed.
Toner A black carbon substance mixed with polyester resins and iron oxide particles.
During the EP printing process, toner is first attracted to areas that have been exposed to
the laser in laser printers and is later deposited and melted onto the print medium.
Transfer corona assembly the part of an EP process printer that is responsible for
transfer ring the developed image from the EP drum to the paper.
Transferring step the step in the EP print process when the developed toner image on the
EP drum is transferred to the print medium using the transfer corona
Typical installation installs the most commonly used components of the software, but
not all of the components.
Unattended installation an installation method that does not require human intervention
once started, and is frequently used when installing over the network. Unattended
installations use answer files to supply the necessary parameters to Windows Setup.
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Virtual memory a general term for a type of computer technology where hard disk space
is used to supplement a computer’s physical memory.
Virus A small, deviously genius program that replicates itself to other computers,
generally causing those computers to behave abnormally.
Vulnerability scanner A software application that checks your network for any known
security holes. Watt The unit of measure for power. Used to rate power supplies and the
related requirements of the various powered components.
WiFi Short for wireless fidelity, it is a collection of IEEE 802.11x standards.
Window A rectangular area created on the screen when an application is opened within
Windows.
Windows Catalog A list of all the hardware that works with Windows and which
versions of Windows it works with. The new name for the Hardware Compatibility List.
Windows Update A feature designed to keep Windows current by automatically
downloading updates such as patches and security fixes and installing these fixes
automatically.
Wireless access point (WAP) a central hub that looks nearly identical to wireless
routers, and provide central connectivity like wireless routers, but doesn’t have nearly as
many features. The main one most people are concerned with is Internet connection
sharing.
Wireless Internet An Internet access technology that uses radio frequency signals to
communicate between ISP and user. It allows the user to roam about a particular area
while remaining connected to the Internet.
Wireless cards an adapter card that gives its host the ability to join a wireless LAN.
Working directory an area on the hard disk where programs store their temporary files
while they work.
Workstation 1) in networking, any personal computer (other than the file server) attached
to the network. 2) A high-performance computer optimized for graphics applications such
as computer-aided design, computer-aided engineering, and scientific applications.
Writing step the step in the EP print process during which the items being printed are
Written to the EP drum. In this step, the laser is flashed on and off as it scans across the
surface of the drum. The area on which the laser shines is discharged to almost ground (-
100V).
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