Computer Hardware:

· Two processor manufacturing companies in world are Intel and AMD.

· Generation characterized by speed, architecture in terms of no. of transistors, size etc.


· Mother Board is the backbone of CPU.

· RAM: Types > SD RAM, DDR1, 2, 3(current tech in use).

· DVD: Digital Video or Virtual Disk.

· Graphic Cards: For graphical application.

· Board Processor RAM decide pc quality.

· Monitor: types CRT, LCD, and LED.


It is an input device used to enter data in computer. Normally keyboard is attached to computer by a cable. It is someway look like a typewriter. It is divided into various types based on their working and keys.


1. 101- Key enhanced keyboard: In 101 keyboard, the layout is of IBM PC/AT339 model. This layout was launched in 1974. It is a complete standard keyboard. In it there is a normal keypad, a row of function key, a cursor keypad, a numeric keypad.

2. 104- Key windows keyboard: in 104 keyboard was launched by Microsoft. It is an advanced version of 101 key keyboard. It has three extra button. Two keys are of windows and one is of menu (mouse right click). Windows button works related windows like opening the start menu.

Menu key is used for right click operation

3. Ergonomic keyboard: A normal keyboard does not provide complete facility to user. Normally we need to turn ours hand during typing because of which there is a case of pain in hands. Ergonomic keyboard is prepared with the mind that the user does not have a pain. The main typing keys of ergonomic board is divided into two types, providing facility two both hand.

4. Multimedia keyboard: multimedia keyboard is designed in standard keyboard layout. Media like cd/dvd, mp3 media file etc. are controlled by it. It has some special key for music player, web browsing.

5. Wireless or cordless keyboard: wireless or cordless keyboard is an advanced version which facilitates the user to use keyboard at any is battery operated.

Keyboard Connectors:

Keyboard connector is at end of keyboard and connects keyboard to computer. They are mainly two type:

1. 5 pin DIN (Deustche Industries Norm) connector: this connector was first used in personal computer (first pc by IBM on 12 Aug in 1981, known as IBM pc). Din connector was made in a circular shape. These connector keyboard were popularly used in 90’s.

2. 6 pin PS/2 connector: it is used to connect keyboard and mouse to computer and made by IBM. This connector is also known as mini din connector. PS/2 port works with 6 pin port. This is used in S-video, mouse and keyboard connection (blue for keyboard and green for mouse).

3. USB 4 pin connector: 4 pin USB (universal serial bus) connector is the most advanced keyboard connector which connects keyboard to computer through USB. It was developed in 1999 to connect computer to other supporting parts. Due to its inexpensive price and easy usability it became very popular.


It is a main input device of a computer which controls cursor and pointer key on display screen. It was invented in 1963 by Douglas C. Angleburt of Stanford research center. This takes cursor on screen to a special point. It is specially used for GUI.

Types of Mouse:

1. Mechanical mouse: This is the oldest type. It has built-in rubber ball. When it is moved on a pad, it rotates the wheel inside the mouse. It has a mechanical sensor which detects direction and mouse movement and produce electronic signal which are sent to computer. The computer then convert it and display it on screen.

2. Opt mechanical mouse: Opt mechanical mouse is an advanced version of mechanical has an optical sensor. In mechanical mouse there is a decoder which detects the distance rolled by mouse. In opt mechanical mouse, led and photo detector together calculate the distance of mouse.

3. Optical mouse: it is the most advanced and latest mouse in which LED is used to measure the rolled over distance of mouse. It has no rotating part.

4. Wireless mouse: it is also like the optical mouse but it is not connected through cable or mouse. It works on radio frequency. It has transreceiver to connect to a computer.


Monitor is an output device which displays the user interface of a computer and the information entered by user.

Types of Monitors:

1. CRT (Cathode Ray Tube) Monitor: It was invented by “Karl Ferdinand Bran”. It was a very heavy thick and was of picture tube. It was a cheap and was used in most computers. In it, an electron beam strikes and collides with light of phosphorous resulting in image formation.

2. LCD (Liquid Crystal Display) Monitor: LCD monitor is among vastly used flat panel monitor. In compare to CRT, it uses very low electric power, slim in size. Hence it is most used in TV, Laptop, digital camera and computer. Nowadays, in LCD monitor thin film transistor (TFT) technique is used to display image on display.

3. LED (Light Emitting Diode) Monitor: LED monitor is latest monitor. It is slimmer, light weight and low power consumptive than LCD. In it LED’s are used to display image. Its contrast ratio is very high which gives us a crystal clear image of high contrast.

Types of Monitor Connector:

1. VGA (Video Graphic Array).

2. DVI (Digital Video Interface).

3. HDMI (High Definition Multimedia Interface)


It is an output device which prints the data processed through computer. Printer prints numbers, letters and graphics on paper. After making a document in computer, we print it using printer which is called printout or hardcopy. Printer can print the document in color or black and white. The speed of printer is measured in PPM (Page per Minute) or CPS (Character per Second).

Types of Printers:

1. Dot Matrix Printer: In dot matrix printer, text and graphics are made in dot by using metal pin in print head. In dot matrix, in between paper and print head there is a ribbon of ink. Print head puts pressure on ribbon and text gets print on paper. Dot matrix printer are used to print the bill. They are also used in carbon copy printing. The number of pins present in print head, also decides the quality of printout. In Dot matrix printer, the quantity of metal pins can vary from 9 to 24. The speed of Dot matrix varies from 30 to 550 CPS. Dot matrix is normally connected to parallel port of computer.

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2. Inkjet Printer: They are more useful in compared to Dot Matrix. Like dot matrix there is also a print head in Inkjet, but there are no metal pins in it. In place of it there are many tiny nozzles which sprints ink on paper. These nozzles are thinner than hair. The print head of this printer is known as print cartridge. In its cartridge there are 50 or more nozzles, and hence its quality is better than Dot Matrix.

3. Laser Printer: They use laser beam for printing. They work on the principle of Electrophotography. It is used in photocopy machine. The main principle of laser printer is static electricity.

4. 3-D Printer:

Optical Media

Optical media means storage like dvd cd which are read by laser. It includes facilities of dvd, cd rom and both, like CD-R, CD-RW, DVD-R, DVD-RW, DVD+R, DVD+RW, Blue-ray etc. In comparison to hard disk, optical media has low seek time (the time which is put in collecting information from different parts of disk). As optical disk does not depend on magnetic charge, so data saved on this disk remains safe for longer time. The quality of these disks in comparison to magnetic is 7 times more. This disk is very much cheaper. These disks are very useful for making back up or transferring data to computer.

1. CD-ROM: It is circular shaped optical disk in which data and application, game and audio file are stored. In it we can store data up to 700 Mb (data of 40 floppies).

CD-ROM Data transfer speed

Types of CD-ROM

Speed (Kb/s)





















In market CD-ROM of 100X is easily available, but it does not work at that speed. Its speed is 1.5 Mbps.

2. CD-R: Compact Disk Recordable has the capacity that it can record the data only once. The data which once recorded in it can’t be formatted. CD-R is also called WROM (Write Once Read Many) technique.

3. CD-RW or CD-Rewritable: This is also called CDE (Compact Disk Erasable). In this we can write data many time after erasing. This normally stores 700 Mb of data.

4. DvD-R (Write Once Read Many): DvD-R disk is of single or double side. It is available in 3.95 Gb, 4.7 Gb or 9.4 Gb. It is of two types: DvD-R (A): For Business user and DvD-R (G) for home user. DvD-R can be write only once.

5. DvD-RW (Rewritable i.e. write many and read many):DvD-RW is similar to that of DvD-R but in it we can erase and again write it. It is normally available in 4.9Gb.

Hard Disk Drive (HDD)

In computer system HDD stores the data of PC. It is used to store all programs and data. Hard disk are most important among permanent storage device. In the beginning Hard disk came in very big size but their storage capacity was very low. Latest hard disk are small, slim and balanced and also their capacity is very much. Old hard disk can store only 50mb data and on their maintenance, much care was needed. But today’s hard disk are shock resistive and have storage up to 3Tb.

Construction and working of hard disk

A rounded and slim platter is used in hard disk. A layer of special type material is laid on the platter. Disk is degenerated to store information. A hole is present in between the the platter to attach it with splinter.

With the help of which a motor rotates at high speed. A special type of electromagnetic read-write device is mounted on slider that is called head which is used to read and write information on disk. Slider are mounted on hand arm and all of these are joined in an assembly and are joined at the surface by device named actuator. A logic board present in the disk controls the work of all components and connect hard disk to cpu.

Hard disk logical structure and file system: hard disk is a medium to store data whose capacity is increasing day by day. As the capacity is increasing, it is getting complicate to use it. Logical structure and software rooting are used to control and to access storage of hard disk and are called file system. Type of logic structure on hard disk logic affects the storage of our system. For computer hardware many types of file system are available which are used in many operating system. Some file system commonly ued are:

1. File allocation table (FAT), FAT 12, FAT 16.

2. Virtual FAT (VFAT)

3. FAT 32.

4. NTFS (New Technology File System)

5. HPFS (High Performance File System)

FAT: In the earlier days of computer FAT was a normal and widely used file system and it uses file system. This file system is used by DOS for the first IBM PC and it was supposed a standard for PC. In starting the FAT file system used 12bit file allocation system which was later made 16 bit which used for hard disk from 1980 to 1990.

VFAT: When in 1995 Microsoft launched Windows 95 in market and a new FAT called Virtual FAT was launched for windows.

FAT 32: AS the storage capacity of hard disk increases the popularity of FAT decreased by time and also its use decreases. To correct this Microsoft invented FAT 32. FAT 32 permitted creating single size partition of large size. FAT 16 has the capacity of only making a partition 2GB. FAT 32 in comparison to FAT 16 use cluster of small size. FAT 32 for the first used for OEM service release 2 of windows. In the all future version FAT 32 was used and it is used in support for windows ME, windows 98. Many non Microsoft product could have used it.

NTFS: Microsoft manufactured windows NT. This was different from previous Microsoft system. the special thing about NT was that a new different file system was prepared for it that was called NTFS. NTFS is much complicated and reliable of any version FAT file system. This was designed for corporate world. Due to its security, capacity and reliability it was also used in networking. In it file by file compression, full permission control, attribute setting, support for all big files and along with transaction dependent work there were many features. In it along with cluster size, hard disk size limit was unbounded.

HPFS: When Microsoft and Intel manufactured OS/2, they wanted that it more capable from DOS and windows version. At that time file system used in pc was only the FAT file system and it had got some limitation like it permitted a file of 11 character only. To overcome these concerns, a new file system specially prepared for OS/2 which was called HPFS. In it file name up to 254 character and mixed case file name are also supported. It efficiently uses the disk space. But due to adverse fate, it was used in a few system and its use was limited to OS/2. Windows NT 3.51 supported it, but from Windows NT 4.0, its support was completely ended.