Computer Hardware

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What is a Computer ? A computer is a device that automatically performs arithmetic or logical operations on information input to it and provides an output according to the performed set of instructions stored within it.

Use Of Computer Computer is an integral part of everyday life. We use the Personal Computer (PC) to perform various tasks. Data storage and processing are the important tasks performed by the PC. It can store, process, and print documents. The use of the PC makes mathematical calculations easier. Scientists use the PC for scientific applications, such as weather forecasts, research, and chemical analysis. PC provides the speediest means of communication through the Internet by sending and receiving e-mails. We can use the Internet to gain information on any topic. We can use the PC for entertainment, such as for watching movies using DVDs, listening to music using CDs and MP3s. We can also download software, graphics, music, and movies from the Internet using the PC. It would be hard to imagine today's world without the PC. A machine that performs such a varied range of functions is hard to define in a few words. Computer is an electronic device that accepts, stores, and processes the data and returns the result or output .

Function Of Computer Personal computer has a microprocessor for processing the data, a keyboard for entering the data, a monitor for displaying the data, and a storage device for storing the data. PC performs many functions such as: Accepting Data Storing Data Processing Data Displaying Data

1. Accepting Data Accepts data input from the user. PC accepts input through various input devices like the keyboard, mouse, or microphone.

2.Storing Data Enables to store large amount of data. This helps to recover the data stored earlier. It can store the data permanently on the storage devices such as the hard disk drive, floppy disk drive, or tape drives.

3.Processing Data Performs operations on the input data. A set of instructions starts these operations. These instructions are either stored in the memory or built into the microprocessor. Data processing is the process of manipulating the data using a set of instructions and producing the desired output. For example, when we write a program and give some input, PC processes the input according to the program and returns the output. In this case, the program is the set of instructions that the PC uses to process the data, which is the input.

4.Displaying Data Shows the processed data to the user. This data can be in the form of binary numbers, characters, or pictures. PC displays the output through various output devices, such as monitors, printers, or speakers. Any device that gives the output from a computer is called the Output device. For example, when we play a CD or DVD, what we see on the monitor or hear from the speakers is the output. The documents that we print after typing and processing are the forms of output from the PC.

Types of Computers Computers perform a vast range of functions. Some computers are so powerful that hundreds or even thousands of users can use them at a single instant. Computers have different types of capabilities and sizes. Classification of computers is based on the usage, speed, and size of computers. There are four main types of computers, namely Microcomputers, Minicomputers, Mainframes, and Supercomputers

Super Computer Supercomputer is the fastest and most expensive type of computer. Supercomputers specialize in high-speed processing of data. The advantage of supercomputers is their speed, which is unmatched by any other type of computer. A major disadvantage of supercomputers is that they generate a large amount of heat during their operation. Hence, it is important to use effective cooling solutions.

Mainframe Computer In the beginning, mainframes were huge computers occupying entire rooms or floors. Mainframes were used to serve as the center of large systems in companies. They now serve distributed users and small servers in a computing network. They are also known as enterprise servers. Mainframes are very large and expensive computers. Thousands of people can use a mainframe at a time. The advantage of mainframes is that it can support so many users and instructions because of its incomparable memory. The disadvantage of mainframe is its huge size and enormous cost.

Mini Computer Minicomputer is a medium sized multiprocessing and multi-user computer. Multiprocessing is the process of running multiple programs or processes at a given instant. The minicomputer is a medium range computer. It is also known as the mid-range server. Minicomputers fall in the category between the microcomputers and the mainframes. The advantage of using a minicomputer is that it can cater to multiple users at a lower cost than mainframes. Minicomputers are ideal for small-sized companies. The disadvantage of the minicomputers is that they are large and bulky.

Micro Computer Microcomputer, also known as a personal computer, is a digital computer that works on a microprocessor. Average people who have a basic knowledge of computers can use microcomputers. Individuals at home and office are the major users of the microcomputer. Microcomputers are widely used for entertainment purposes such as for playing games, listening music, and watching movies. The microcomputer is also widely used to access the Internet. The microcomputer has several advantages such as small size, low cost, and portability. Its main disadvantage is that the speed of processing is low as compared to other types of computers.

Types of Portable PCs Laptops Notebooks Subnotebooks Palmtops Portable PCs vary in size and features. One type of portable PC is the laptop that is comparable to a briefcase in size and structure. Notebooks and sub notebooks are smaller versions of laptops. The palmtop is small enough to be held in the palm of the hand. Example are as follow:-

Laptops A laptop is a portable computer that can perform all of the tasks carried out by a desktop system. This type of computer is small enough to fit on the lap of a person, hence the name. You can use a laptop to create programs, multimedia applications, word documents, presentations, and spreadsheets. A laptop is like a briefcase in structure and you can carry it around wherever you go. A laptop appears

Notebooks A notebook is an extremely small and lightweight version of a portable computer. They can fit into a briefcase and be carried around. Currently, notebooks and laptops are virtually the same in most respects. Notebooks use flat panel technologies to produce a lightweight display screen. A notebook appears.

Subnotebooks Subnotebooks are a smaller and lighter version of the notebook. They generally have smaller keyboards and screens as compared to notebooks. Subnotebooks usually have external drives and may have the serial and parallel ports on an external device. A subnotebook appears.

Palmtops As the name suggests, palmtops are computers that you can carry around in the palm of your hand. These computers use a pen for input and not the keyboard. Most palmtops do not have disk drives because of their size limitations. Palmtops are also called Personal Digital Assistants (PDAs), handheld computers or pocket computers. A palmtop and the pen appear.

General Concepts of Computers A computer is a device that automatically performs arithmetic or logical operations on information input to it and provides an output according to the performed set of instructions stored within it. Hardware, Software and Firmware together make up a computer system. Hardware describes all the physical components used in the assembly of the computer. Software constitutes the instructions on which the computer acts which thus makes the computer usable. Firmware are programs that are permanently written and stored in computer memory.

Firmware Firmware are programs that are permanently written and stored in computer memory. ROM (Read Only Memory) BIOS (Basic Input Output System) POST (Power On Self Test)

R O M Read only means that the programs and data can only be read from it. Therefore, programs and data cannot be written to it. Most PCs contain small amount of ROM to stores programs that enables the computer to boot. It is a non-volatile memory and therefore, it is referred to as a permanent data storage area.

BIOS The BIOS software enables you to control the system and the different hardware components without loading the operating system. The BIOS contains the code required to operate the hardware devices connected to the system such as the keyboard, mouse and the different ports connected to the system. The BIOS chip is of two types.

CMOS ( Complementary Metal Oxide Semiconductor ) The CMOS is the memory located on the motherboard that stores the BIOS settings. The CMOS has a size of 64 bits. When the system starts the BIOS loads the settings from the CMOS. The CMOS requires a power source to store the settings. It receives power from a battery that is installed on the motherboard. This battery must be replaced when it becomes weak or you may lose the stored BIOS settings. You can clear the BIOS settings stored in the CMOS using the jumpers located on the motherboard or by removing the battery from the motherboard

POST (Power-On Self-Test ) When the system starts, the BIOS runs the power-on self-test (POST) to test the hardware connected to the system. These are the testing routines that are store in ROM BIOS. When POST delete an error either from the Keyboard, Mouse, Display or Memory or various other component it produces an error warning in the form of Message or Beep sound.

Starting a PC for the First Time When we start the PC, the Basic Input Output System (BIOS) runs a test to check if all the peripheral devices, memory and hardware of the PC are working properly. This test is called the Power On Self Test (POST). The PC will boot only if the results of the test are positive. If any of the above components of the PC are not in proper condition, the PC will give some warning signals like beeps. In some cases, if the problem is serious, the PC will not boot at all. The POST happens as soon as the PC starts and before most of the components of the PC start. The errors that cause the system to stop booting are of two types – fatal and non-fatal. In case of fatal errors, the boot process stops immediately. The following are the functions performed by POST: Checking the motherboard Comparing the system configuration with the PC Configuration Program to find any changes made Checking the memory devices and drives Checking the system memory Starts the display and audio devices In case there are no errors in the system configuration or devices, a single beep follows the POST. Then the booting process of the PC starts and the operating system is loaded.

Classification of Software System Software Application Software

System Software System Software instruct the computer to control and manage its internal functions, like initializing on start-up, controlling external devices, organizing the memory during operations and many other activities. Eg. DOS,Windows 98 ,Windows XP

Application Software Application Software consists of programs which carry out the specific processing required for user's application such as Word Processor, Spread Sheets, and Financial Accounting or a computer-aided package. Eg. MS Office, Tally, A-CAD etc.

OS (Operating System) OS is program that act as an intermediary between a user of a computer and component of the computer Hardware. There are two Goal of OS 1) Primary Goal to make the computer system convenient to use for the use. 2) Secondary Goal is to use the computer Hardware. OS controls and co-ordinate the use of the computer Hardware in among the various application program for the various user of the computer. OS is one program running at all times on the computer i.e. Kernel with all the other program.

Function Of OS OS provide the method for other programs to communication with the hardware of computer. It create a user interface and to enables user to make changes in the computer. OS must enables user to determine the installed programs and then, use, and shutdown the program of their own choice. OS should enables user to add, move and delete the installed program and data.

Operating Systems and BIOS Hardware in a PC does not know the software and BIOS is the interface between hardware and software. BIOS is also called firmware due to its integration with hardware. BIOS contains all the code required to control the keyboard, display screen, disk drivers, serial communications and a number of miscellaneous functions. BIOS is typically placed in a ROM chip that comes with the computer it is often called a ROM BIOS which ensures that the BIOS will always be available and will not be damaged by disk failures.

Classification of Operating Systems Operating system is conceptually broken into two components: – Shell- an outer wrapper to the kernel which in turn talks directly to the hardware. – Kernel -the primary code of an operating system

Based on the types of computers they control and the sort of applications they support, OS’s are of the following types Single-user, Single task In this type, OS is designed to manage the computer so that only one user can effectively do one thing at a time. Eg. DOS Single-user, multi-tasking In this type, OS will let a single user have several programs in operation at the same time. Eg. Windows 98 Multi-user In this type, OS allows many different users to take advantage of the computer's resources simultaneously. Eg. Unix, Windows 2000, Linux etc.

DOS (Disk Operating System) History of DOS Towards the 1980s, a number of personal computers had appeared on the market, based on 8-bit microprocessor chips such as the Intel 8080. IBM made the decision to enter the market with a 16-bit processor, the Intel 8088. IBM realized that it did not have time to develop its own operating system and at that time CP/M written by Gary Kendall from Digital Research dominated the market. IBM had negotiations with Digital Research but the negotiations did not result in an agreement. IBM then had given the contract to write the new OS to Microsoft.

In 1979, a small company called Seattle Computer Products decided to write its own operating software to test some of its Intel based products which was called QDOS (Quick and Dirty Operating System) made by Tim Patterson. Microsoft bought the rights to QDOS for $50,000 keeping the IBM deal a secret from Seattle Computer Products. Microsoft made slight changes to QDOS and then presented "Microsoft Disk Operating System" or MS-DOS to IBM. IBM PC was announced in August 1981, with version 1.0 of MS-DOS. More than 50 other hardware manufacturers also used DOS, after IBM selected MS-DOS. Microsoft designed DOS to run on an 8086 processor and never truly upgraded DOS to take advantage of the more advanced Intel processors' protected mode. MS-DOS remains as it began, a single-tasking OS. Interface of DOS was command line, meaning that there was no mouse, no menus, or any graphical components. Text commands were entered from the keyboard and the computer's response appeared as text on the monitor. DOS manifests each program and piece of data as an individual file. Names are broken down into two parts: the filename and the extension

Filenames can be no longer than eight characters and extension, which is optional, can be up to three characters long. No spaces or other illegal characters (/ \ [ ] | < > + = ; , * ?) can be used in the filename or extension. The file name and extension are separated by a period, or "dot." and this naming system is known as the "eight dot three" (written as "8.3") system. Examples of DOS filenames: – WORD.EXE – SYSTEM.INI – AJAY.DOC Drives and Directories DOS assigns a drive letter to each hard drive partition and to each floppy or other disk drive. DOS cannot support more than two floppy drives and are assigned drive letters A: and B: Hard drives start with the letter C: and can continue to Z: if necessary. DOS uses a hierarchical directory tree to organize the contents of these drives.

DOS Structure Three main files of DOS are as follow :- IO.SYS MSDOS.SYS COMMAND.COM. IO.SYS handles all the talking to the BIOS and hardware. MSDOS.SYS is the primary DOS code, often called the kernel. COMMAND.COM actually interprets commands typed into the computer and passes that information to MSDOS.SYS. It is also called the Shell or command interpreter.

Commands Of DOS VER----------------------- Current Version Of Windows TIME--------------------- Current Time DATE--------------------- Current Date MD------------------------- New Folder CD-------------------------- Go inside the Folder CLS------------------------- Clear screen DIR------------------------- To see hole Directory CD..------------------------- One step backward CD\------------------------- Go Fully Back COPY CON--------------- New file TYPE----------------------- Content of the file EDIT------------------------ Edit the file REN------------------------- Rename the file DEL------------------------- Delete the file RD--------------------------- Remove folder COPY----------------------- Copy file in other Directory ATTRIB –H--------------- Hide Folder ATTRIB +H -------------- Unhide Folder DIR/A---------------------- To see all Hidden Folder DIR/S---------------------- To see the system File & Folder DIR ????-------------------- To Search Any Folder & File EXIT------------------------ To Close DOS CHKDSK------------------ Detail of Drive SHUTDOWN –S--------- To shutdown SHUTDOWN –R---------To Restart SHUTDOWN –L--------- To Log Off

Different Between Window XP Professional & Window 2000 Professional ASR No ASR GPO No GPO Workgroup and domain member Workgroup Member Support 2 Processor Support1 Processor Encryption No Encryption Yes No Remote desktop Windows XP Profession Windows XP Home

Different Between Window XP Professional & Window 98 No Disk Quota Disk Quota No GPO Support GPO Support FAT 16, 32 & NTFS Support FAT 32 & NTFS Support 1 Processor Support 2 Processor No Encryption Support Encryption No Remote Desktop Support Remote desktop Windows 98 Windows XP Professional

Different Between Window 95 & Window 98 Support FAT 16, 32 & NTFS Support FAT 16 & FAT 32 Support Direct X No Direct X Multiple Monitor Single Monitor Support USB No USB Support Windows 98 Windows 95

Computer System Computer System HARDWARE SOFTWARE FIRMWARE KEYBOARD MOUSE HARD DISK DRIVE FLOPPY DISK DRIVE MOTHERBOARD PROCESSOR RAM CD-ROM SMPS MONITOR PRINTER/SCANNER SYSTEM APPLICATION O.S N.O.S DRIVERS READYMADE TAILORMADE ROM BIOS POST

Computer Hardware KEYBOARD MOUSE HARD DISK DRIVE FLOPPY DISK DRIVE MOTHERBOARD PROCESSOR SMPS RAM PRINTER MONITOR SCANNER Web Cam CD-ROM

1.KEYBOARD Keyboard is the primary input device of the PC. You use the keyboard to enter commands and type text. The keyboards on computers are similar to typewriters. However, a computer has many additional keys. Computer keyboards have not changed a lot since they were introduced. The only changes have been additions to the number of keys in the original keyboards. Present day keyboards have 101 or more keys. Each of these keys performs a different operation.

TYPE OF KEYBOARD AT Keyboard P/2 Keyboard USB Keyboard

AT Keyboard AT (Advanced Technology) Keyboard The 5-pin DIN connector was widely in use in the past. The DIN stands for Deustche Industries Norm. This type of connector is rarely used nowadays. (Male connector)

PS/2 Keyboard PS/2 (Personal Standard/2) IBM introduced the PS/2 port on the back of PCs to connect devices such as the mouse and the keyboard. The PS/2 port supports the 6-pin PS/2 connector, which is very popular in the present. It has replaced most of the 5-pin DIN connectors. The 6-pin PS/2 connector is also known as the 6-pin mini DIN connector

USB Keyboard USB (Universal Serial Bus) Keyboard The 4-pin USB connector for keyboards is fast replacing the 6-pin PS/2 port as the most widely used connector for keyboards. The USB keyboard is connected to the USB port on the back of the computer and tends to be the fastest.

2.MOUSE Douglas Engelbart invented the computer mouse in 1963. It is a device that enables a computer user to move the cursor or pointer to a specific point on the screen. It was given its name because of its appearance and movement, which are similar to those of a mouse. When you move the mouse, the cursor on the screen also moves in the same direction. The mouse is the most used input device after the keyboard. The mouse is particularly important for Graphical User Interface (GUI) applications. You can also use the mouse for drawing objects on the screen by using the mouse as a pencil or paintbrush

Types of Mouse Devices There are different types of mouse devices that are widely in use at present. The connected mouse has been replaced to a great extent with cordless and optical mouse devices Mechanical Mouse Optomechanical Mouse Optical Mouse Cordless Mouse

Mechanical Mouse A mechanical mouse is the oldest type of mouse available today. This type of mouse consists of a rubber or metal ball on the underside. The mouse is placed on a mouse pad. As the mouse is moved, the ball rolls in the appropriate direction. This type of mouse has mechanical sensors that detect the direction of movement of the mouse and send signals to the computer to move the pointer accordingly.

Optomechanical Mouse The Optomechanical mouse is similar to the mechanical mouse. However, this type of mouse makes use of optical sensors instead of mechanical sensors. The optomechanical mouse is more accurate than the mechanical mouse.

Optical Mouse An Optical Mouse uses laser technology to detect the movement of the mouse. It is the most accurate and precise type of mouse. The optical mouse has no moving parts. The optical mouse must be moved along a special mouse pad that has grids on its surface. The grids on the mouse pad provide a frame of reference for the working of the mouse.

Cordless Mouse A cordless mouse establishes an infrared or radio link with a transceiver (transmitter/receiver) that is connected to the computer through a cable. Cordless mouse are very convenient and easy to use. Cordless mouse operate on batteries.

Mouse Connectors Serial Connector PS/2 Connector USB Connector

Serial Connector The serial mouse connects to the serial port on the computer. This type of connection offers low speed and hence it is being replaced with other connections like the PS/2 and USB ports.

PS/2 Connector The PS/2 mouse port on the back of the PC connects to the mouse. This port was originally invented so that other devices like modems could use the serial port. The PS/2 port was also known as the mouse port. This is the most widely used port for connection of a mouse to the computer.

USB Connector Some types of mouse devices connect to the computer through the USB port. The USB connection offers good speed.

3. Hard Disk Drive A hard disk is the primary and permanent data storage device that is placed in the system. It is similar to a human brain where all the past and present events are stored. It is made up of a magnetic material that helps in storing data for the system by following the magnetic recording techniques. A hard disk stores data from 1 GB to 160 GB or even more depending on the capacity of the hard disk. A hard disk consists of several circular platters and each platter has read/write heads on both the sides of it. The platters are divided into concentric rings, called as tracks, and each track is divided into number of sectors. The read/write heads examines and then records the data in these sectors.

Types of Hard Disks The different hard disks specify the speed at which the hard disk transfers data and the reliability of the hard disk in storing the data if the hard disk crashes. Advanced Technology Attachment (ATA) Serial ATA (SATA) Small Computer Systems Interface (SCSI)

The ATA transfers data between the hard disk and the system using 16 bits with speeds of upto 100 MB per second. You can connect two hard disks to a single controller on the system. You must set the hard disk to master or slave using the jumpers on the hard disk, so that the system can identify the required hard disk. This hard disk uses a 40-pin connector to connect to the system. And 4 Pins Power Connector. Advanced Technology Attachment (ATA)

The Serial ATA transfers data between the hard disk and the system using only 1 bit at a time with the speed of upto 600 MB per second. You can connect only one Serial ATA hard disk to a single controller on the system, thus this hard disk does not have settings such as master, slave or cable select. The Serial ATA hard disk uses a 7 wire cable to connect to the system. And 15 Pins or 4 Pins Power Connector. Serial ATA(SATA)

The SCSI interface enables the hard disk to communicate with the system at very fast speeds. This interface is used on network servers that perform a lot of processing. The SCSI supports upto eight devices on a single cable and is used with RAID. The SCSI hard disk uses a 68 wire cable to connect to the system. And 4 Pins Power Connector. Small Computer Systems Interface (SCSI)

Components of the Hard Disk The different components such as the platters, the read / write head and the head actuator form the hard disk. These components are sealed inside the hard disk compartment known as Head Disk Assembly (HAD)

Platters The platters are round disks that are made up of metal or glass. The platters of glass are preferred, as the shape of the glass does not change when the hard disk heats up. The platters in the hard disk are stacked over each other. The size of the platter determines the size of the hard disk

Read/Write Head The Read/Write head is used to read the data stored on the hard disk and also write the data to the hard disk. While reading, the head converts the data from binary to a magnetic pulse. The magnetic pulse charges the magnetic coating on the platter and stores the data on the disk. While reading data from the disk, the head reads the magnetic data stored on the disk and converts them to binary and sends it to the system. Every platter in the hard disk has two read/write heads one on each side of the platter. While the disk is reading or writing data to the disk the head does not touch the disk. However, when the disk stops spinning the head gently rests on the stationary disk.

Head Actuator Mechanism The head actuator is used to move the read/write head from the center of the platter to the edge of the platter, moving from one track to the next. This enable the read/write head to position itself over the required hard disk sector and access the data from all the parts of the disk when the disk is spinning.

Spindle Motor The Spindle Motor is used to spin the hard disk platters. These motors are very precise and reliable, as they have to spin for many continuous hours. The spindle motor must spin without causing a lot of vibrations as the slightest vibration during the operation of read / write can damage the hard disk.

Logic Board The Logic Board contains the circuit for controlling the hard disk. All the connectors from the system connect to the logic board. The logic board stores the data on the hard disk platters. Sometimes the logic board of the hard disk may fail due to surges in the power supply. In such a case you can replace the logic board of the hard disk.

Hard Disk Jumpers You can also set the hard disk to master, slave or cable select as per the jumper settings displayed on a label affixed on the top cover of the hard disk. If you have two hard disks installed on the system, you must set the jumper of one hard disk to master and the jumper of the other hard disk to slave. This ensures that the correct hard disk responds to the system calls. The system considers the master first and then the slave while assigning drive letters. The system also boots the primary partition from the hard disk set as master.

Working of the Hard Disk The hard disk stores the data on the magnetic platter coating. The user executes a command, or the program requests information from the hard disk. The motor in the hard disk drive rotates the platters. The read write head moves over the required track and the read write head reads the data from the hard disk. The hard disk drive sends the data to the microprocessor for processing. The motor stops rotating the platters in the hard disk. The steps followed by the hard disk to write data on the hard disk: The user executes a command, or the program sends data to be written on the hard disk. The motor in the hard disk drive rotates the floppy disk. The read write head moves over the required track to read the track address from the hard disk for storing the data. The write head is energized. The write head converts the binary data into electromagnetic impulses and writes the data on the hard disk. The motor stops rotating the platters in the hard disk.

Types of File System The file system determines the way that the files and folders are stored on the hard disk. The type of the file system that you want to format the hard disk with depends on the operating system that you want to install and the features that the file system offers. File Allocation Table (FAT) FAT16 FAT 32 New Technology File System (NTFS Extended File System (EXT)

File Allocation Table (FAT) The FAT file system stores the pieces of file data known as clusters on the hard disk. These clusters are stored on different locations of the hard disk. The FAT file system has a file allocation table that holds the information where the different clusters of a file are saved. It also lets the system know if a sector on the hard disk contains data or is empty.

FAT16 FAT16 uses a 16 bit binary number to identify the cluster number that stores the data on the hard disk. FAT16 file system is used on hard disks that have a medium storage capacity. It can be used on hard disks that have the capacity of upto 2 GB. The operating system such as Disk Operating System (DOS), Windows 3.x and 95 makes use of the FAT file system.

FAT32 FAT32 uses a 32 bit binary number to identify the cluster number that stores the data on the hard disk. FAT32 file system is used on hard disks that have a very large storage capacity. It can be used on hard disks that have the capacity of upto 2 Tetrabytes (TB). The operating system such as Windows 98 / 2000 / ME / XP makes use of the FAT file system.

New Technology File System (NTFS) The NTFS file system offers a high level of security for the stored files. The NTFS file system is reliable as it ensures that when you save data to a file, all the updated data from the memory is saved to the file or none of the updated data is saved. This ensures that the file does not get corrupted when it is saved, due to any physical or technical problems such as a power failure. The operating system such as Windows NT / 2000 / 2003 makes use of the NTFS filesystem.

Extended File System (EXT) The EXT file system has a root directory and all the files and folders are stored in this root directory. The EXT3 file system also has a feature called Journaling that keeps a log file with the data that must be stored on the hard disk. This ensures that the data does not get corrupted due to power failures. The operating system such as UNIX and Linux makes use of the EXT filesystem.

Installing the Hard Disk The system can read and write data to the hard disk after it is installed. You must also set the BIOS settings for the system to identify the hard disk

Best practices 1. Check if the system supports the hard disk capacity. 2. Check the type of the hard disk that you can install. 3. Check the instructions and the settings specified on the label affixed on top of the hard disk. 4. The hard disk may be pre-configured as master as per the factory settings. Let this setting be as it is if you are installing only one hard disk on the system.

Precautions 1. Switch off the power supply before opening up the system. 2. Unplug all the cables of external devices connected to the system. 3. Wear an anti-static wristband. 4. Do not drop the hard disk. 5. Insert the signal cables carefully into the hard disk taking care not to damage the pins. 6. Ensure that the marking on the signal cable faces the power cable connector on the hard disk

Hands on exercise To install the hard disk : 1. Configure one hard disk as master and the other as slave if you are installing two hard disks in the system on the same IDE cable. 2. Open the system case. 3. Locate an empty drive bay in the system case. 4. Insert the hard disk into the drive bay and attach screws to hold it in place. 5. Connect one end of the signal cable to the motherboard.

Inserting Power Cable 8. Connect the second hard disk, if any to the system. 9. Close the system. 10. Restart the system and press Delete to enter the BIOS setup. 11. Browse to the Standard CMOS Setup page and ensure that the Type options are set to Auto. 12. Save and exit the BIOS. 13. Restart the system. 14. Boot into windows. 15. Create partition on the hard disk using the Disk Management Utility or Fdisk. 16. Format the partitions created.

Partitioning the Hard Disk Partitioning is used to divide the hard disk into sections known as drives. Partitioning makes your system start faster and it also enables you to install multiple operating systems on the different partitions such as you can have Windows 98 on the first partition and Windows XP on the second partition. The different partitions on the hard disk are assigned drive letters to enable you to access the drive. You can have upto four partitions on a single hard disk. You can create partitions using the Fdisk utility. The Fdisk utility enables you to specify the size in MB that you want the size of the drive to be. You can also enter a percentage value that specifies the size of the partition on the hard disk. For example, suppose you have a hard disk of the capacity 10 GB and you specify the partition size as 25%, then Fdisk will create a partition of the size 2.5 GB.

Primary Partition A hard disk can have upto four primary partitions on the system. However, you can only mark one partition as an active partition. This active partition contains the Master Boot Record for starting the system. Your system must have one Primary partition

Extended Partition A hard disk drive can have only one extended partition. The extended partition can be further divided into logical drives. The logical drives are assigned drive letters to identify the drive.

NOTE 1. You must decide the number of operating systems that you will install on the system before you partition it. 2. You must decide the size of the partitions based on the data that you will store on the partition. 3. Copy and paste the file Fdisk.exe from the C:\Windows\Command folder located on a system having Windows 95 / 98 to a bootable floppy disk. A bootable floppy disk has system file that enables you to start the system using the floppy disk. 4. Restart the system after creating all the partitions and drives using Fdisk.

To create a primary partition using Fdisk: 1. Restart the system and insert the bootable floppy in the floppy disk drive. 2. Type Fdisk at the command prompt and press enter. The system displays the information. 3. Type Y and press enter. The Fdisk Options Page appears. 4. Select 1 and press Enter. The Create DOS Partition or Logical DOS Drive screen is displayed 5. Type 1 and press Enter. The Create Primary DOS Partition screen is displayed To create a primary partition using all the available space on the hard disk, type Y and press Enter . 6. Type N and press Enter . The screen set the size of the partition is displayed 7. Type the required partition size in MB such as 600 to create a primary partition of 600MB and press Enter . The screen displaying the information of the partition created is displayed 8. Press Esc . The Fdisk options page is displayed.9. Press Esc to exit Fdisk.

To create an extended partition: 1. Run the Fdisk utility. The Fdisk options page is displayed. 2. Type 1 and press Enter . The Create DOS Partition or Logical Disk Drive screen is displayed. 3. Type 2 and press enter. The Create Extended DOS Partition screen is displayed. 4. Type the size in MB that you want to set the size of the extended partition and press Enter . The extended partition is created and displayed 5. Press Esc to return to the Fdisk options page. 6. Press Esc to exit Fdisk.

To create logical drives on the extended partition: 1. Run the Fdisk utility. The Fdisk options page is displayed. 2. Type 1 and press Enter. The Create DOS Partition or Logical DOS Drive screen is displayed. 3. Type 3 and press Enter. The screen to create logical drives is displayed 4. Type the size in MB that you want to create the logical drive such as 260 and press Enter. The screen shows the logical drive created5. Similarly, you can create logical drive using the disk space on the extended partition. 6. Press Esc after all the logical drives are created. The Create DOS Partition or Logical Drive screen is displayed. 7. Press Esc to return to the Fdisk Options page. 8. Press Esc to exit Fdisk.

To set the active partition: 1. Run the Fdisk utility. The Fdisk options page is displayed. 2. Type 2 and press Enter to set a partition as an active partition. The screen displaying the different partitions created is displayed. 3. Type 1 and press Enter to set the primary partition specified at 1 as the active partition. The primary partition is set to active and the screen is displayed 4. Press Esc to return to the Fdisk options screen. 5. Press Esc to exit Fdisk

Formatting the Hard Disk Formatting the hard disk creates the sectors, tracks and places the file system on the hard disk. This prepares the hard disk so that the system can store files on the hard disk. Formatting a hard disk erases all the contents of the drive. Therefore, you must back up the files on the system before formatting a hard disk. You must also format a hard disk after you install a new hard disk on the system or to erase all the contents on the disk, especially if the disk is infected with a virus that cannot be cleaned by the anti-virus software. Low Level Formatting High Level Formatting

Low Level Formatting The Low Level formatting is also called physical formatting. During low level formatting the system creates the tracks and the sectors on the hard disk. The hard disk is formatted using low level formatting at the factory

High Level Formatting The High Level formatting is also called logical formatting. This creates the necessary file systems on the hard disk for storing the files and folders on the hard disk. You can use the software format.com to perform a high level formatting. You can copy this file from the Windows\Command folder and paste it on a bootable floppy that enables you to start the system when it does not boot. The system also performs a high level formatting during the process of installing the operating system.

Small Computer Systems Interface (SCSI) The Small Computer Systems Interface (SCSI) pronounced as scuzzy enables you to attach hardware peripherals to the system. The SCSI system consists of the SCSI controller that communicates with the system. The SCSI cables connect the SCSI drives to the SCSI controller and the SCSI devices

Advantages of SCSI SCSI enables fast communication between the system and the device. The SCSI connects many devices but has only few slots on the motherboard. The advantages of SCSI are : 1) The SCSI devices have data transmission speeds that can reach about 320 Mb per second between the system and the device. 2) It allows you to attach upto 15 devices to a single SCSI port. 3) The SCSI controller on the SCSI devise boosts the signals and enables the devices to be connected at a distance of about 25 meters from the system. 4) The SCSI devices reduce the processing load on the microprocessor, as they have a microcontroller built into the device. 5) The communication problems between the system and the SCSI device due to data signals reflecting back when cables are left open are reduced, as the ends of the SCSI have terminators

3.Floppy Disk Drive (FDD) Introduction : The floppy is an external storage device. It is a magnetic round disk enclosed in a plastic jacket. The data is stored on the magnetic surface of the floppy disk. You can transfer data from one computer to another using a floppy disk. The floppy disk drive reads and writes data to a floppy disk

History of Floppy Alan Shugart created the floppy disk drive in the year 1967. The floppy disk for this floppy disk drive was 8 inches in size. This floppy could store data on one side and the floppy disk drive could only read the data from the floppy. The capacity of this floppy was about 100 KB. The floppy disk drive was upgraded to read and also write to floppy disks. The capacity of the floppy disk also increased to hold 250 KB

8 Inch Floppy Disk The size of the floppy disk was reduced to 5.25 inches. This disk was similar to the 8 inch disk and could store 160 KB of data. The 5.25 inch floppy was modified to store data on both sides of the disk. This increased the storage capacity of the floppy disk to 360 KB. The floppy disks were of low density. The density of the floppy specifies how the data is stored on the floppy. The more the density of the floppy disk the closer the data is stored and this increases the amount of data that the floppy disk can hold. The 5.25 inch floppy disk was enhanced and the density of the floppy disk was increased. The double-sided high-density floppy disk holds 1.2 MB of data. The 5.25 inch floppy disk has a Write Protect notch. Covering this notch using a tape or piece of paper protects the data on the floppy disk by making it only available for reading. This floppy disk has an Index hole that enables the floppy disk drive to identify the starting sector of the floppy disk. The write access part of the floppy disk enables the floppy disk drive head to read from and write data to the floppy disk.

5.25 Inch Floppy Disk The size of the floppy disk decreased and reduced to 3.5 inches. The thickness of the floppy jacket was increased. Floppy disks of different sizes ranging from 2 to 4 inches were created to compete with the 3.5 inch floppy disk. The 3.5 inch floppy disk was standardized by the industry. The 3.5 inch floppy had a high density and could hold 720 KB of data. The floppy disk was then improved and the density increased to create a high-density floppy disk that could hold 1.44 MB of data. The 3.5 inch floppy disk was then improved and the double-sided floppy disk was created that could store data on both sides of the floppy disk

3.5 Inch Floppy Disk The 3.5 inch floppy disk has two holes at the bottom of the disk. One enables the floppy disk drive to identify if the floppy disk has a low density or high density. The other is a write protect switch of the floppy disk. This switch enables us to protect the data on the floppy disk from being accidentally modified or erased. Sliding the switch down makes the floppy disk read only. You must 131 slide the switch upward to enable data to be read and written to the floppy disk.

Types of Floppy Disk Drives Floppy disk drives are available in different sizes. The floppy disk drive shares the name with the size of the floppy disk that it uses. For example, the floppy disk drive that uses the 3.5 inch floppy disk is called the 3.5 inch floppy disk drive.

5.25 Inch Floppy Disk Drive Older systems used the 5.25 inch floppy disk drive to read and write data to the 5.25 inch floppy disk. This drive has a lever on the front of the drive that must be turned clockwise, to lock the floppy disk in after inserting the disk in the drive. You must turn the lever anti-clockwise before removing the floppy disk from the drive

3.5 Inch Floppy Disk Drive The 3.5 inch floppy disk drive can read and write data to the 3.5 inch floppy disk. The 3.5 inch floppy The 3.5 inch floppy drives spins the floppy disk at a speed of 300 rotations per minute. This enables the floppy to be formatted with 80 tracks on each side of the disk. Each track is divided into 18 sectors. The sector can hold 512 bytes. The 3.5 inch floppy disk drive also has an eject button that is used to remove the floppy disk from the drive.

Components of the Floppy Disk Drive The floppy disk drive consists of different parts. These parts interact with each other and perform the functions of reading and writing data on the floppy disk. It is important to know the different components of the floppy disk drive before servicing the drive, and to understand the working of the floppy disk drive.

Read Write Head The floppy disk drive has a read write head. This part performs the work of reading and writing data on the floppy disk by converting the binary signals to electro magnetic signals. The double-sided floppy disk drive has two heads on both the sides of the floppy disk drive to read and write data on both sides of the floppy disk. The position of the read write head on both sides of the drive is such that they are not opposed to each other. This positioning prevents any interruption between the heads while writing data on the floppy disk. The floppy disk drive uses the same head to perform both the actions of reading data and writing data on the floppy disk. The floppy disk head consists of two parts. The first part reads and writes data on the floppy disk. The second part is a set of two heads that erases the data from a track before the read write head writes the data on the track.

Head Actuator The Head Actuator allows the read write head to access all the tracks on one side of the floppy. The head actuator moves the read write head forward, from the center of the floppy outwards, and backward to place the head over the required track. The head actuator is connected to a motor that moves the head forward and backward. This motor is the stepper motor.

Spindle Motor The Spindle Motor spins the floppy disk in the floppy disk drive. The spindle motor has a clamp that catches the floppy disk when the floppy disk enters the floppy disk drive. The spindle motor rotates at a speed of 300 rotations per minute.

Circuit Board The Circuit Board connects all the parts of the floppy disk drive together. It consists of the circuits that sends the data signals to the different parts of the floppy disk drive. The function used to run the floppy disk drive is built into the circuit board. It controls the speed of the motors and manages the position of the read write head over the required track.

Connectors The power supply connector supplies power to the floppy disk drive. The 3.5 inch floppy disk drive uses a small sized connector called the mini plug. The 5.25 inch floppy disk drive uses the larger connector Cables The data cable connects the floppy disk drive to the motherboard. The 3.5 inch floppy disk drive uses the 34 pin data cable connector. The cable comes with a special twist that enables the system to assign the floppy disk drive as drive A or drive B.

Sectors and Tracks The steps followed by the floppy disk drive to read data from the floppy disk: The user executes a command, or the program requests information from the floppy disk. The spindle motor in the floppy disk drive rotates the floppy disk. The stepper motor moves the read write head over the required track and the read write head reads the data from the floppy disk. The floppy disk drive sends the data to the microprocessor for processing. The spindle motor stops rotating the floppy disk in the floppy disk drive. The steps followed by the floppy disk drive to write data on the floppy disk: 135 The user executes a command, or the program sends data to be written on the floppy disk. The spindle motor in the floppy disk drive rotates the floppy disk. The stepper motor moves the read write head over the required track for the read write head to read the track address from the floppy disk for storing the data. The erase coils located on the read write head erases the data from the track. The write head is energized. The write head converts the binary data into electromagnetic impulses and writes the data on the floppy disk. The spindle motor stops rotating the floppy disk in the floppy disk drive.

Installing the Floppy Disk Drive You must install the floppy disk drive to the motherboard to make it accessible to the system. To connect the floppy disk drive we require the floppy disk drive and the connecting cable. 1) Turn off the power supply and unplug all external devices connected to the system. 2) Check the front panel of the system case to check if there is a vacant slot to install the floppy disk drive. 3) Check the data cable if you can attach additional devices to it. 4) Check if there is a spare power supply cable to connect to the floppy disk drive. 5) Wear an anti-static wristband. 6) Insert the connectors gently so as not to damage any hardware. 7) Open the system case. 8) Remove the plastic panel from the front of the system case. 9) Slide the floppy disk drive into the case opening from outside of the system case. 10) Attach screws to hold the floppy disk drive in place. 11) Connect the power cable to the floppy disk drive 12) Connect one end of the data cable to the motherboard. 13) Connect the other end of the data cable to the floppy disk drive according to the drive letter that must be assigned to the floppy disk drive 14) Close the system case.

To configure the floppy disk drive : 1. Start the system. 2. Press the Del key on the keyboard. The BIOS settings appear. 3. Select the Standard CMOS Settings. The screen displaying the CMOS settings appears. 4. Select the required floppy disk drive. 5. Modify the option to display the installed floppy disk drive. 6. Save and Exit the BIOS settings. The BIOS settings may differ from one motherboard to the other, you can refer to the motherboard manual to configure the floppy disk drive.

To format a floppy disk : 1. Take the floppy disk. 2. Check the write protect notch to ensure that it is in the read write mode. 3. Insert the floppy disk in the floppy disk drive. 4. Double-click My Computer from the desktop. 5. Right-click the 3.5 inch floppy icon. The pop-up menu appears. 6. Select Format from the pop-up menu. 5. Right-click the 3.5 inch floppy icon. The pop-up menu appears. 7. Select Format from the pop-up menu.

To create a bootable floppy disk: 1. Format the floppy disk as shown above. Slide the write protect tab on the floppy disk to the read write mode. 2. Open My Computer after the format is complete. 3. Browse to the C:. 4. Select the system files ntldr, ntdetect.com and boot.ini, required to boot the system. 5. Select Edit _ Copy to copy the files. 6. Browse the floppy disk using My Computer. 7. Select Edit _ Paste to place the copied files on the floppy disk. 8. Remove the floppy disk from the floppy disk drive. 9. Slide the write protect tab on the floppy disk to the read only mode. Ensure that windows explorer is configured to display system and hidden files. In My Computer, use the Tools _ Folder Options and click the View tab to view hidden files.

5.CD-ROM AND CD WRITER DRIVES Introduction : The data stored on the CD can last for many years. The CD can store large amounts of data and is used to distribute software, music, and movies. The CD drive reads the data stored on the CD. The CD-ROM drive can only read data from a CD. Today CD-R and CD-RW drives are available that can read, and also burn data on a CD.

CD-ROM Disc The 3.5 inch floppy disk stores about 1.44 MB of data. This enabled users to only copy files of small size on the floppy disk. The CD stores more data than the floppy disk. The CD holds about 650 - 700 MB of data. The CD is made out of a clear piece of polycarbonate plastic. The CD has different layers that enable the CD drive to read data from the CD. The layers that make up the CD depend on the type, and the number of times that you can write data on the CD.

CD-ROM Drive The CD-ROM drive can read data from the CD-ROM disc and the Audio CD. You can use this drive to install software from a CD and play music from an Audio CD. The speed of the CD drive specifies the amount of data the CD drive reads from the CD in a second. This speed is called the transfer speed of the CD drive. The original speed of the CD drive is 150 KB per second. The speed of the CD drive is specified using a number followed by X. For example, if the speed of the CD drive is specified as 52X, then the CD drives reads data from the CD at a speed of 52X. The number specifying the speed of the CD drive must be multiplied with the original speed of 150 KB per second, to get the speed of the CD drive. For example if the speed of the CD drive is specified as 12X, then the transfer speed is 12 x 150 = 1,800 kbps.

Connectors The IDE cable connects the CD drive to the motherboard. The CD drive uses the 40 pin connector. You must ensure that the marking on the IDE cable is on the same side of the power supply cable when inserting it in the CD drive. The CD-ROM drive is also equipped with output connections for sound. You can connect the cable from here to the sound card or the sound output device.

Jumpers Jumpers are switches on the hardware that enables you to change the hardware settings. The CD drive jumpers are located at the back of the CD drive. It enables you to set the CD drive as the master, or the slave. The master specifies that the hardware is set as the primary device and can control the other devices set as slave. You can also use the jumper to set the CD-ROM drive as the master or slave as per the cable selection using the IDE cable When you install two devices on the same cable one must be set as master and the other as slave. You must set the jumpers to cable select if you use a special cable to attach the devices to the motherboard. The special cables architecture sets one device to master and the other to slave.

To set the sequence of the boot devices : 1. Start the system. 2. Press the Delete key on the keyboard when the message to load the setup appears, the BIOS Setup Main menu page appears. Note that the page displays the keys required to browse to the different options. 3. Browse to the Advanced Setup option. 4. Press Enter to display the Advances Setup screen. 5. Browse to the 1st Boot Device option. 6. Select the required device such as the CDROM. 7. Press Esc to display the BIOS Setup Main menu page. 8. Save and exit the BIOS Setup.

DVD ROM AND COMBO DRIVES Introduction : Digital Versatile Disk or Digital Video Disk (DVD) is a form of digital storage. DVD is used to stores music, video, games, and multimedia applications. The DVD is similar to the CD in appearance and structure. The DVD offers higher capacity and better quality as compared to the CD. The DVD storage capacity is seven times that of a CD. To play a DVD, a DVD ROM drive is used. In addition, combo drives are available that play DVDs as well as CDs.

DVD-ROM The DVD-ROM disk stores data ranging from 4.7 GB to 17 GB. DVD-ROMs store films, computer software in a similar manner to CD-ROMs.

6.Motherboard The motherboard connects the CPU, hard drives, memory, and every other part of a system by means of slots, connectors, and sockets. The motherboard chipset is a series of chips that is a part of the motherboard. The chipset is very important to the operation of the system.

Types of Motherboards Motherboards differ according the type of system you use. The capacity and efficiency of motherboards differ based on the system type. You can classify motherboards on the basis of system type as desktop motherboards, server motherboards and laptop motherboards. Desktop Motherboards Server Motherboards Laptop Motherboards

Desktop Motherboards The desktop motherboard is used in Personal Computers and Desktops Computer. As it is used for applications at home and in office, this type of motherboard is the most basic type

Server Motherboards Server motherboards are more advanced than desktop motherboards and are designed to offer high-end services. These motherboards support expansion and future upgrades and can handle major applications. Server motherboards also offer improved graphics and can usually support different types of memory technology.

Laptop Motherboards A laptop motherboard connects to all the different parts of a laptop system. It is the most important part of the laptop. These motherboards generally have very advanced features as compared to the desktop motherboards.

Form Factors of Motherboard The form factor of a motherboard refers to its physical shape, layout, and the positioning of the components on it. The form factor of the motherboard determines the type of system case it will fit into. Some motherboards that have the same functionality can be packaged in different form factors. The only major difference between such motherboards will be the form factor. Motherboards are available in different forms. Are as follow:- Advanced Technology (AT) Baby AT Advanced Technology Extended (ATX) Form Factor

Advanced Technology (AT) Form Factor The AT form factor is also known as the full-size AT form factor. This form factor matches the original IBM AT motherboard in structure and layout. This type of motherboard is very large and is about 12 inches wide and 13.8 inches deep. The AT form factor is not used much by present-day motherboard manufacturers. This type of motherboard does not fit into most of the popular system cases and its size also makes installation and troubleshooting difficult.

Baby AT Form Factor The baby AT form factor was the most popular till recently. This form factor is very much similar to the original IBM XT motherboard structure. The baby AT form factor fits into most of the system cases. A baby AT motherboard is 8.5 inches wide and about 13 inches long. The length of baby AT motherboards is not fixed

Advanced Technology Extended (ATX) Form Factor Intel invented the ATX form factor in the year 1995. The ATX and mini ATX form factors are the most popular ones presently. The ATX form factor has many of the best features of the LPX and AT form factors. The ATX form factor is not compatible with the LPX or AT form factors. As a result, new system cases and power supplies were designed to match this form factor. These cases and power supplies have now become quite common. The ATX

Components of a Motherboard The motherboard has several connectors, jumpers and expansion slots for connecting various components of the system. You can connect various devices of the system to the connectors and expansion slots of the motherboard. You can configure the motherboard using the jumpers.

Expansion Slots The expansion slots on a motherboard enable you to connect the expansion cards to the motherboard. The different PCI cards include LAN card, SCSI card and USB card. The cards must comply with PCI specifications. The motherboard has an Accelerated Graphics Port (AGP) slot. You can connect AGP cards that are compatible with your motherboard, to the AGP slot.

Bus Standards There are different types of I/O buses that transfer data across components of the system. The different buses have different widths and speeds. The common bus standards are:

Video Electronics Standards Association (VESA) Local Bus Was the first local bus used in PCs. It is a 32-bit bus that runs at a speed of 33 MHz. VLB was introduced to address video problems in personal computers. VLB is no longer used and has been largely replaced by the PCI bus. VLB slots are used to connect VLB video cards.

Peripheral Component Interconnect (PCI) Local Bus Is the most popular I/O bus. It has the same speed and width as the VESA local bus. Some PCI buses have a width of 64 bits. It provides much better performance as compared to the VESA local bus. It has separate circuitry that controls it. PCI generally supports 3 or 4 slots. You can connect video cards, SCSI host adapters and network cards to the PCI expansion slot.

Accelerated Graphics Port (AGP) Bus Provides high performance graphics capabilities to a system. This bus forms a dedicated path between the chipset and the graphics subsystem. The AGP bus enables creation of 3D graphics.

Industrial Standard Architecture (ISA) Bus Is a widely used standard even though it has remained unchanged since its creation. The ISA bus can support a wide range of devices. It has a bus width of 8 or 16 bits.

Extended Industrial Standard Architecture (EISA) Bus Compatible with ISA cards and with a bus width of 32 bits. This standard is rarely found on desktop systems.

Microchannel Architecture (MCA) Bus Incompatible with older cards and has a bus speed of 16 or 32 bits. IBM created this standard in the 1980s. This standard is not used nowadays.

Chipsets The term chipset means a set of chips, as the name suggests. It is a group of integrated circuits and microprocessors. The chipset on a motherboard determines its functionality. You must choose your chipset according to the attributes you want your system to have. The chipset and controllers on a motherboard are the intelligence of the system. The chipset therefore affects every aspect of the performance of a system. The chipset controls the data transfers between every component of the system. Previously, a single chip or multiple chips performed every function of the chipset. Over time, all these chips were integrated to form the chipset that controlled system operations. A modern chipset consists of Northbridge and Southbridge. These two microchips to a large extent determine the features and capabilities of a motherboard. The Northbridge handles data communication between the memory and the CPU. Whereas the Southbridge handles data from the PCI, ISA slots and other devices that arenot under the control of the Northbridge. The type of CPU you use determines the chipset you can use. Every chipset supports a CPU interface. The CPU interface can be Socket 7, Slot 1, or Socket 370. So the chipset that you choose must support the interface required by your CPU. Some of the leading manufacturers of chipsets are Intel, AMD, and VIA. You must choose the appropriate chipset depending on your needs.

Intel Chipsets Intel is the leading manufacturer of chipsets worldwide. You can choose from a wide range of Intel chipsets for your system. Some of the Intel Chipsets with their characteristics are listed below.

Chipset Processor Max. Memory USB Ports Type Intel 820E Pentium III, 1 GB 4 Mainstream PC Pentium II Intel 815P Celeron, 512 MB. 2 Mainstream PC Pentium III Intel 915G Pentium IV 4 GB 8 Mainstream PC Express Intel 925X Pentium IV, 4 GB 8 Performance PC Express Pentium IV

AMD Chipsets AMD manufactures a wide variety of chipsets that are very popular. Listed below are some of the AMD chipsets with their features.

Chipset Processor Max. Memory Memory Module USB Ports Size AMD 750 Socket A 768 MB 128 MB 4 Duron/Athlon AMD 760 Socket A 2 GB non-reg., 512 MB 4 Duron/Athlon 4 GB reg. AMD 760 MP Athlon MP 4 GB 512 MB 4 AMD 760 Athlon MP 4 GB 512 MB 4

VIA Chipsets VIA is another leading manufacturer of chipsets. Some of the IVA chipsets and their features are listed below.

Chipset Processor Max. Memory Memory Module USB Ports Size VIA KM133 Socket A 1.5 GB 256 MB 4 Duron/Athlon VIA KLE133 Socket A 2 GB 256 MB 4 Duron/Athlon VIA KM266 Socket A 3 GB SDRAM, 512 MB 6 Duron/Athlon 4 GB reg.

I/O PORTS AND DEVICES Introduction : Input/Output ports (I/O) enable you to connect hardware devices such as the keyboard, mouse, printer and scanners to the system. It is the entry and exit point for data from the system. I/O ports give you freedom in choosing and installing the device because if you have only few ports you can select a device that is available for that port.

Types of Ports The ports have different shapes and sizes, thus before purchasing a device you must check if you can attach the device to the system using the port available on the system. You must not force a device plug into a port or you may bend the pins. Some devices such as the keyboard and the mouse port on newer systems use the PS/2 ports that look the same but can be differentiated using the port color.

Serial Ports A serial port is like a single lane road that sends and receives one bit of data at a time. Thus, the eight bits of data in one byte travel one bit at a time, one behind the other. The serial port connector also known as the Communication or COM port can have 9 or 25 pins. A serial port is used to connect devices such as the mouse and modems to the system.

Parallel Ports The parallel port is like an eight lane road that transmits eight bits of data at a time. It is like eight cars moving on a wide road side by side. The parallel port connector has 25 pins to connect devices such as printers, scanners, external hard drives, and tape backup devices.

DIN 5 Port The DIN 5 port is used to connect the keyboard to the system. This port is also called the AT port and uses 5 pins for connecting the keyboard.

PS/2 Port The PS/2 port is used to connect the keyboard and mouse to the system. The ports are available in a color that matches the color of the plug connecting the mouse and keyboard. This port uses 6 pins to connect the device.

Universal Serial Bus (USB) Ports The USB port is a rectangular port that is used to connect a variety of devices to the system. The USB port also supplies power to the device such as the web camera, if the device does not use an external power source. To use the USB device you must just plug the device into the USB port, as most USB devices offer Plug-and-Play support. However, you must install the USB driver before using the USB port.

USB Port You can connect upto 127 devices to the system using the USB port using a USB hub. The device and the system connected using the USB can be at a maximum of 30 meters, thus you can connect 5 hubs to the USB.

USB Hub The USB cable connects the system to the device and can have a maximum length of 5 meters, as the USB cable design does not support it due to electromagnetic fields. The USB cable has two different connections - one at each end of the USB cable, connection A and B. Connection A connects to the system and appears.

USB Connection A Connection B is used to connect the USB cable to the device. Devices that have the USB cable built into them do not have this connection. USB Connection B The USB port is available in different versions having the same port shape. The different versions of USB ports available are: 1) USB version 1.0 - Provides data transfer speed of 1.5 Mega bits per second 2) USB version 1.1 - Removes bugs from USB version 1.0 3)USB version 2.0 - Provides data transfer speed of 10 Mega bits per second The USB port enables you to connect devices such as mouse, printers, scanners, digital cameras, modems, and speakers.

Infrared Ports Devices use the infrared ports to communicate with the system without using wires. The devices send out infrared signals that enter the system through this port. The infrared port appears.

7.MICROPROCESSORS Computer is capable of performing complex tasks, such as managing the brake system of a car. These tasks are processed by the Central Processing Unit (CPU). The CPU comprises of the microprocessor. The microprocessor accepts input from the user in the form of the data and instructions. It processes the data using the instructions and sends the processed information to the output device. The microprocessor controls the system, therefore it is important to understand it's working. The choice of the microprocessor also depends on computing needs .

The microprocessor is a chip that accepts data and instruction, processes it and gives the output. An instruction is a calculation that the microprocessor processes such as adding two numbers. One of the key elements of the microprocessor is its speed. The speed of the microprocessor depends on various factors such as the number of instructions it processes, the bandwidth, and the clock speed. The bandwidth specifies the number of binary digits that the microprocessor can process in a single instruction. The clock speed specifies the speed at which the microprocessor processes an instruction. The speed of the microprocessor also depends on the number of the transistors built into the processor. The transistors in the microprocessor boost the data signals on the processor. The more the transistors built on the microprocessor the faster is the speed of the microprocessor. The advancements in technology have reduced the size of the transistors and have increased the processing speed of the processor. Microprocessors may also have a cache to store information. The microprocessor can access information faster from the cache than from the RAM Overview of Microprocessors

Type Along With Date 1971 ------------------ 4004 1972 -------------------8008 1974 -------------------4040 / 8080 1979 -------------------8008 1982 -------------------80286 1985 -------------------80386 series 1989 -------------------80486 series 1993 -------------------Pentium family 1997 -------------------Pentium II Family 1998 -------------------Celeron / Xeon family 1999 -------------------Pentium III family 2000 -------------------Pentium 4 family

Microprocessor Sockets The socket on the motherboard connects the microprocessor to the motherboard. The microprocessor has pins that enter the motherboard using which the microprocessor communicates with the system. Motherboards that use the socket to install the microprocessor use the Zero Insertion Force (ZIF) or the Low Insertion Force (LIF) design to install the microprocessor on the motherboard. The ZIF uses a lever to install or remove the microprocessor, thus the microprocessor can be installed and removed without using any force. You must use force to push the microprocessor in the LIF socket. You must use special tools such as a screwdriver or a chip puller to remove the microprocessor from the LIF socket. Microprocessors support different voltages. The voltage required by the microprocessor is adjusted automatically by the microprocessor, however you may have to adjust the jumpers on the older motherboard. Jumper is a switch present on the hardware that enables you to configure the hardware.

Socket 1 Socket 1 supports microprocessors that have 169 pins. In this socket, the pins are arranged in three rows. Socket 1 supplies maximum 5 volts to the microprocessor. This socket supports the 80486 and 80486 Overdrive microprocessor. The Overdrive microprocessor can be installed on different sockets. These are used on older motherboards

Socket 2 Socket 2 supports microprocessors that have 238 pins. In this socket, the pins are arranged in four rows. Socket 2 supplies maximum 5 volts to the microprocessor. This socket supports the 80486 and Pentium OverDrive microprocessors.

Socket 3 Socket 3 supports microprocessors that have 237 pins. In this socket, the pins are arranged in four rows. Socket 3 supplies 3.3 to 5 volts to the microprocessor. The voltage can be adjusted using the jumpers on the motherboard. This socket supports the 80486, AMD 5x86, and Pentium OverDrive microprocessors.

Socket 4 Socket 4 supports microprocessors that have 273 pins. In this socket, the pins are arranged in four rows. Socket 4 supplies maximum 5 volts to the microprocessor. This socket supports the Pentium 60-66, and Pentium Overdrive microprocessors.

Socket 5 Socket 5 supports microprocessors that have 320 pins. In this socket, the pins are arranged in five rows. Socket 5 supplies maximum 3.3 volts to the microprocessor. This socket supports the Pentium 75-133 MHz, Pentium OverDrive microprocessors.

Socket 6 Socket 6 supports microprocessors that have 235 pins. In this socket, the pins are arranged in four rows. Socket 6 supplies maximum 3.3 volts to the microprocessor. This socket supports the 80486 microprocessor.

Socket 7 Socket 7 supports microprocessors that have 321 pins. In this socket, the pins are arranged in five rows. Socket 7 supplies 2.5 to 3.3 volts to the microprocessor. The processors for this socket use 2.5 volts for input-output, whereas the core of the microprocessor uses 3.3 volts. This socket supports the Pentium 75-200 MHz, and Pentium OverDrive microprocessors.

Socket 8 Socket 8 supports microprocessors that have 387 pins. In this socket, the pins are arranged in five rows. Socket 8 supplies 3.1 to 3.3 volts to the microprocessor. This socket supports the Pentium Pro microprocessors. The Socket 8 is more rectangular in shape than the other sockets.

Socket 370 Socket 370 supports microprocessors that have 370 pins. In this socket, the pins are arranged in six rows. The microprocessors for this socket have the L2 cache built into the microprocessor. This socket supports Celeron 2 and Pentium III microprocessors.

Socket 462 Socket 462 is also known as Socket A. This socket supports microprocessors that have 462 pins. The microprocessors for this socket have the L2 cache built into the microprocessor. This socket supports the Athlon and Duron microprocessors .

Socket 478 Socket 478 supports microprocessors that have 478 pins. The microprocessors for this socket have the L2 cache built into the microprocessor. The Socket 478 microprocessor supports the Intel Pentium 4 microprocessor.

Microprocessor Slots Microprocessors such as the Intel Pentium II, III, Xeon, Celeron, and AMD Athlon are installed on cards. The card with the microprocessor on it is installed on the motherboard. The card is built in with the L2 cache. This speeds up the processing because the processor can store the instructions in this cache.

Slot 1 Slot 1 supports microprocessors that have 242 pins. The microprocessor is mounted on a card that uses Socket 8. Slot 1 supplies 2.8 to 3.3 volts to the microprocessor. This slot supports the Pentium II, III, and Celeron microprocessors.

Slot 2 Slot 2 supports microprocessors that have 330 pins. This slot supports the Pentium Xeon microprocessors. This slot is found on server motherboards.

Slot A Intel patented the Slot 1. This allowed only Intel to manufacture microprocessors that used this slot. AMD created the Slot A to support the Athlon microprocessors. This Slot A uses the EV6 protocol that enables the microprocessor and the RAM to communicate at an increased speed.

Working of the Microprocessor The microprocessor is a complex chip in the system. The different parts of the microprocessor work together to process the data and give the user information. The various parts of a microprocessor are as follows. Input – Specifies the system input devices Output – Specifies the system output devices Arithmetic and Logic Unit (ALU) –Performs all the arithmetic calculations such as addition and subtraction and the logical calculations such as the AND and OR operators Control Unit (CU) – Controls the flow of the data and information to other units of the microprocessor Memory / Cache – Stores the data and instruction required by the microprocessor The data and the instructions for processing the data enter the microprocessor from the input device such as the keyboard. The CU stores the data and the instructions in the Memory/Cache and sends the instructions to process the data to the ALU. The CU retrieves the data required by the instructions in the ALU from the Memory / Cache. The ALU processes the data using the instructions and sends the result to the CU. The CU stores the result in the Memory / Cache and sends it to the output device such as the monitor or printer when required.

Interface of the Microprocessor Data and information flows from the microprocessor to the different devices connected to the system. Hardware devices such as the hard disk, floppy disk, and printer are connected to the microprocessor using a bus. The size of the bus determines the amount of information that can travel between the two devices in a clock speed of the microprocessor. There are two types of buses, the serial bus and the parallel bus. On a serial bus, the data travels between two devices one bit at a time. On a parallel bus, more than one bit of information can travel between two devices.

The steps the microprocessor follows to interface with a device are : 1. The microprocessor checks the status of the device. 2. The microprocessor requests the device for transferring data. 3. The device sends the data request to the microprocessor. 4. The microprocessor sends the required data to the device.

8.Memory Introduction : Memory is one of the functions of the brain that enables to store and remember the past events. Similarly, in computers the term memory refers to a chip that stores data. It also enables us to retrieve the stored data. The processor retrieves the information stored in the memory for processing the data. The storage capacity of a memory depends on the type of the memory package used

Types of Memory Memory can be categorized into two types, namely volatile memory and non-volatile memory. Volatile memory loses the data as soon as the system is turned off. On the other hand, non-volatile memory does not lose the data even after the system is turned off. Apart from this classification, you can classify the memory into physical memory, virtual memory, and flash memory

Memory Primary Memory Secondary Memory ROM RAM HDD FDD PEN Drive ZIP Drive P-ROM EP-ROM EEP-ROM S-RAM D-RAM Synchronous EDO RAM SD-RAM DDR-RAM RD-RAM EDO RAM FPM RAM

Physical Memory Physical memory comprises of memory chips. Physical memory stores programs and data that the microprocessor requires. Therefore, it enables the microprocessor to access the required programs and data quickly. The different types of physical memory are: Read Only Memory (ROM) Random Access Memory (RAM)

Read Only Memory(ROM) Read only means that the programs and data can only be read from it. Therefore, programs and data cannot be written to it. Most PCs contain small amount of ROM to stores programs that enables the computer to boot. It is a non-volatile memory and therefore, it is referred to as a permanent data storage area.

Type of ROM P-ROM (Programmable Read-Only Memory ) EP-ROM (Erasable Programmable Read-Only Memory ) EEP-ROM (Electrically Erasable Programmable Read-Only Memory )

P-ROM Stores the programs permanently. Data can only be written once to the PROM. A PROM is a non-volatile memory

EP-ROM Clears the program when exposed to the ultra-violet rays. Therefore, the EPROM can be reprogrammed after the program has been erased.

EEP-ROM Clears the program when exposed to the electrical voltage. Therefore, the EPROM can be reprogrammed after the program has been erased.

Random Access (RAM) Random access means any byte can be accessed in any order. The microprocessor can read and write programs and data to the RAM. It is a type of a volatile memory and therefore it is referred to as a temporary data storage area

Type of RAM S-RAM D-RAM DDR-RAM RD-RAM

S-RAM (Static Random Access Memory ) This memory is referred to as Static because of the fact that it does not require refreshing like DRAM. SRAM stores the data as long as the power is supplied to the system. This is because SRAM is made up of transistors that do not require refreshing. SRAM is used as the computer's cache memory.

D-RAM (Dynamic Random Access Memory ) Today, most PCs use DRAM as the temporary data storage area. DRAM stores data in the memory cells. Each memory cell contains a transistor and a capacitor. Capacitors lose their charge quickly and as a result, they need to be refreshed. Refreshing helps to retain the data in the memory. The life of data in DRAM is very short for about few milliseconds. In order to retain the data, the storage cells need to be refreshed after few milliseconds. Because of the constant refreshing of cells, this memory is referred to as Dynamic RAM

TYPE of D-RAM EDO RAM (Extended Data-Out DRAM ) EDO DRAM is faster than normal DRAM. This is because EDO DRAM starts fetching the next block of memory before the previous block of memory is sent to the processor. It is also known as hyper page mode DRAM

SD-RAM (Synchronous Dynamic Random Access Memory ) SDRAM synchronizes the memory speed with the CPU clock speed. The speed of the SDRAM depends on the speed of the CPU bus. It is faster than SRAM, DRAM, EDO DRAM, and VRAM memories. The data transfer speed of SDRAM is measured in nanoseconds and megahertz units. It runs with an average speed of 133 MHz.

DDR-RAM (Double Data Rate Random Access Memory ) It is the latest version of SDRAM. DDR is synchronous with the system clock. As a result, the data transfer rate of DDR is faster than SDRAM. It is almost twice the speed of the SDRAM. This memory chip consumes less power. DDR memory supports error correction code and non-parity. The server uses the error correction code, normally called as ECC.

Difference between SRAM and DRAM SRAM stores data till the power is switched off, whereas DRAM stores data only for a few milliseconds. SRAM uses a set of transistors for each memory cell, whereas DRAM uses a single transistor and capacitor for each memory cell SRAM does not refresh the memory cell after each reading of the transistors reading of the capacitor whereas DRAM needs to refresh the memory cell after each reading of the transistors reading of the capacitor In case of SRAM Data access is faster whereas in case of a DRAM data access is slower. SRAM consumes more power whereas in case of a DRAM power consumption is less SRAM is more expensive then DRAM

Virtual Memory Today, most PCs use 64MB or 128MB of RAM. However, this MB of RAM may not be sufficient enough to run all the programs that you want to run at a time. Virtual memory enables the computer to work as if it has more RAM than it actually has. Therefore, it helps to increase the speed of the PC. For example, if you simultaneously work with multiple applications such as the Windows operating system, a Windows Explorer, an e-mail program, a Web browser, a Word processor, 64MB of RAM may not be sufficient to run all these programs. In order to run another program, you would have to close some of the currently running programs. However, this problem can be solved using the virtual memory. Virtual memory copies the programs not used frequently to the hard disk. Therefore, it frees up the space in the RAM to run the new programs. Virtual Memory comprises of a set of memory addresses called virtual addresses. Programs can use these virtual addresses to store data and instructions. To copy the virtual memory into the RAM, the operating system divides the virtual memory into units called pages. These pages are stored on the hard disk. When a program is executed, the pages are copied from the hard disk to the RAM. The process of copying the pages from the hard disk to the main memory is called paging or swapping. Windows operating systems from Windows 95 onwards supports virtual memory. The DOS operating system does not supports the concept of virtual memory.

Flash Memory Flash memory is used in the digital camera, cellular phones, LAN switches, PC Cards for notebooks, and video games. This memory performs the action in a flash and as a result, it is termed as the flash memory. Flash memory is a non-volatile memory. It is a type of EEPROM consisting of blocks. EEPROM is erased and reprogrammed in blocks. Flash memory is faster than EEPROM since it is reprogrammed at the block level whereas EEPROM is reprogrammed at the byte level

Working of RAM RAM stores the data until the processor is executing the current data. Once the processor finishes the current execution, RAM forwards the next data to the processor. The processor accesses the data from the RAM in a random order with the help of the memory cell address. The address lines contain the transistors and the capacitors for reading the data. When the capacitor is charged, the memory cell returns a bit value as 1. When the capacitor is empty, the memory cell returns the bit value as 0. In DRAM, each cell contains a pair of transistor and capacitor. Each cell represents a single bit of data in the binary format of 0 and 1. The capacitor stores the data in the memory cell. The transistor with the help of the memory control circuit reads these memory cells. A transistor acts as a switch. It turns on when the control circuit reads the capacitor. It turns off when the capacitor is empty. The DRAM controller refreshes the capacitor after each reading of the memory cell. DRAM refreshes automatically.

Memory Packages Memory package is a small circuit board that contains memory chips. SIMM, DIMM, SODIMM, and RIMM are some of the memory packages. These packages are the form factors of a RAM chip. The installation of a memory depends on the form factors of a RAM. A form factor is the size and shape of the memory packages.

Type of Memory Package Single In-line Memory Module (SIMM) 30-pin SIMM Package 72-pin SIMM Package Dual In-Line Memory Module (DIMM) Small Outline Dual In-line Memory Module (SODIMM) Micro DIMM Rambus In-line Memory Module (RIMM)

Single In-line Memory Module (SIMM) SIMM is a small circuit board designed to hold the memory chips. It contains pins for accepting data from the control circuit. These circuit boards or modules are known as packages. There are various SIMM packages available based on the number of pins it contains. For example, 30-pin package and 72-pin package

30-pin SIMM Package The capacities of a 30-pin SIMM package are 256KB, 1MB, 2MB, 4MB, 8MB, and 16MB RAM. It contains 2, 4, or 8 data chips per module. A 30-pin SIMM package has a data bus width of 8 bits with 9-bit parity. Parity checks the accuracy of the data transmission. An odd parity and an even parity are the two modes of parity checking.

72-pin SIMM Package A 72-pin SIMM package has 32-bit data width with 36-bit parity. PS/2 is another term used for the 72-pin SIMM package. The capacities of a 72-pin package are 1MB, 2MB, 4MB, 8MB, 16MB, 32MB,64MB, and 128MB RAM. It contains 2, 4, 8, or 16 data chips per module. FPM DRAM uses a 72-pin SIMM package

Dual In-Line Memory Module (DIMM) DIMM package is also a small circuit board that contains the memory chips. The difference between the SIMM and DIMM is that DIMM is a 168-pin package. The data widths of the DIMM packages are 64-bit, 72-bit, or 80-bit. A 168-pin DIMM package is available in the SDRAM, EDO, or FPM DRAM chips. A 168-pin DIMM package has 84 pins on each side of the package. This type of pin configuration helps in placing the DIMM package on the memory socket. The latest computers use a DIMM package. Its pin configuration does not support the motherboard of the old computers. A DIMM package is available in 8MB, 16MB, 32MB, and 64MB sizes. It supports 3.3V and 5.0V of electricity

Small Outline Dual In-line Memory Module (SODIMM) The laptops and notebook systems use this package. It is the smallest version of the DIMM. The SODIMM package has a notch at the bottom of the circuit board. This notch helps in inserting the SODIMM package in the memory socket. SODIMM packages are available with 144 and 200 pins. A 144-pin SODIMM package has 64-bit data path. The FPM DRAM and EDO DRAM use this package. The 72 pins on both the sides of the package divide a 144-pin package. A 200-pin SODIMM package has 64-bit data path. PC2100 memory and PC2700 memory use this package. The 100 pins on both the sides of the package divide a 200-pin package

Micro DIMM Micro DIMM stands for Micro Dual Inline Memory Module. This package is smaller than DIMM and SODIMM packages. The sub-notebook systems use these memory packages. The Micro DIMM package pins connect the memory module with the memory socket. These pins provide two communication lines for the module and the system. This package does not have the notch at the bottom. Micro DIMM packages are available with 144 and 172 pins. A 144-pin Micro DIMM package has 64-bit data path. PC100 SDRAM uses this package. The 144- pin Micro DIMM package has two sides. It contains 72 pins on each side of the package. The height of this chip is 1.545 inch long and 1 inch high. A 172-pin DDR Micro DIMM package has 64-bit data path. It is installed in 64-bit systems. The high performance network applications performed by the systems use this package.

Rambus In-line Memory Module (RIMM) RDRAM chip uses the RIMM memory package. This package is same as the DIMM package. It only differs in the pin configuration. The high bandwidth and the low latency applications use this memory package. The RIMM package has a data storage speed of 600 MHz, 711 MHz, 800 MHz, and 1066 MHz. It has 184 connecting pins. The distance between each pin in the RIMM package is 1mm. This package starts operating from 2.5 voltage supply. The RIMM packages are available in 16-bit data buses, 32-bit data buses, and 64-bit data buses. The memory bandwidth of the RIMM package is up to 9.6 GB per second.

9. SMPS (Switch Mode Power Supply) The power supply unit supplies power to the different system components such as the motherboard and the device drives. You must protect the system from extreme temperature changes like overheating using cooling devices. You can also use a UPS to protect the system from power fluctuations.

Functions of Power Supply The power supply junction supplies the electric current to the terminal as AC. However, the power supply unit of the system needs DC with some signals for the motherboard. As a result, the power supply unit of the system converts the AC to the DC for its use. The power supply unit of the system generates high-frequency signals during the electric current conversion from AC to DC. This frequency may harm the components of the system. To prevent damage to the system the power supply unit is packed in a metal box

Type of Power Supply Personal Computer / Extended Technology (PC/XT) Advanced Technology (AT) Form Factor Advanced Technology Extended (ATX) Form Factor

Personal Computer / Extended Technology (PC/XT) The PC/XT power supply case is the used by the IBM PC/XT systems. The placement of the PC/XT power supply is at the top right side of the back end of the system case. This power supply case has a toggle switch, placed on the power supply unit enables you to switch the power supply unit on and off. The PC/XT also has a voltage selection switch controls the input voltage. It can accepts around 130W of power. The PC/XT system uses the AT connector to connect to the motherboard. _ The manufacturer presets the voltage selection switch for standard conditions. The user may not have to adjust it. The voltage selection switch is red in color.

Advanced Technology (AT) Form Factor The AT power supply known as IBM PC/AT is placed at the top center of the back end of the system case and an up/down toggle switch controls the operation of the power supply unit. The PC/AT system uses the AT form factor of the power supply along with the AT motherboard. It accepts around 192W of power supply voltage. The PC/AT system uses the AT connector to connect to the motherboard.

Advanced Technology Extended (ATX) Form Factor The ATX system uses the New Low Profile Extended (NLX) power supply, hence the ATX form factors are also known as the ATX (NLX) form factors. The NLX form factor does not have a power outlet to connect the power cord of the monitor to the power supply unit. This power supply fan draws air from outside the system and blows it inside of the system to cools the system. This power supply unit uses the ATX connector to connect to the motherboard.

Components of Power Supply A power supply unit consists of different functional components and each of these components has values for the power supply unit. The components of the power supply are power switches, power connectors, and power supply fan.

Power Switches The power switches are used to switch the power supply for the system on and off. The PC/XT systems have the power switch at the rear end of the system case that enables the user to switch the system on or off. The AT tower system cases has a power switch placed on the front side of the system case. This power switch uses connecting wires for connecting with the power supply unit of the system.

Remote Power Switch The ATX system cases use electronic power switches and the switch circuitry connects the motherboard with this switch. It follows a soft power method that uses a power on signal from the motherboard that enables the power supply to switch the system on

Molex Connector The disk drive power connectors use 4 wire connectors. The 4 wire connectors are available in two sizes, a large size and small size connectors. The hard disk drive, CD/DVD drives uses the larger size connectors, commonly called as Molex.

Mini-Plug Connector The 3.5-inch floppy disk drive uses the smaller size connectors, called as mini-plug.

Power Supply Fan Power supply fan is used for cooling the system. The power supply fan is normally located at the rear end of the power supply unit. Some power supply fans use sleeve bearings motor and some uses ball bearing motors. The power supply fan also removes the air out of the system and protects the system components from dust or dirt. A power supply fan may stop working due to the over heating of the system components or the power supply components.

Colour Coding & Voltage Of AT Power Supply Voltage Colour PIN Voltage Colour PIN Pin 9 Pin 8 Pin 12 Pin 6 Pin 11 Pin 5 Pin 10 Pin 4 Pin 9 Pin 3 Pin 8 Pin 2 Pin 7 Pin 1

Colour Coding & Voltage Of ATX Power Supply Pin 20 Pin 10 Pin 19 Pin9 Pin18 Pin 8 Pin 17 Pin 7 Pin16 Pin 6 Pin 15 Pin 5 Pin 14 Pin 4 Pin 13 Pin 3 Pin 12 Pin 2 Voltage Voltage Pin 11 Pin 1 Colour Colour PIN PIN

To install a power supply unit in the system : Open the system. Insert the power supply unit in the system case and align the screw holes of the system case with the screw holes of the power supply unit. Fix the screws of the system case with the screws of the power supply unit. Adjust the voltage selector switch of the power supply unit to 115V, or 220V, or 230V. The 115V of voltage selection is for those regions placed outside India and the 220V or 230V of voltage selection is for India. Connect the motherboard connector and the disk drive connectors of the power supply unit to the motherboard and the respective drives of the system. Close the system. Insert one end of the power cord to the power supply unit and the other end to the power supply junction. Switch on the toggle switch placed on the power supply unit. Ensure that the power supply fan should be facing outside the system case.

10.MONITOR Introduction : Video adapters are responsible for delivering the images to the monitor. They enable the monitor to display images using a variety of colors. They also give images a realistic feel and look. The monitor is like a television that displays text and graphics on the screen. The monitor is an output device that displays on the monitor screen, the information requested by the user from the system.

Video Adapters The video adapter is a chip installed in the system. Video adapters display both 2 Dimensional (2D) images such as textual information, and 3 Dimensional (3D) images such as those required for movies and games. The video adapter. Video Adapter The microprocessor sends the display image to the video adapter. The video adapter draws the required image and sends it to the monitor for displaying

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