Hardware of Computer | Hardware Components and their Functions

Hardware of Computer: Those parts of computers which we can touch and feel are hardware items. A computer system is in itself a combination of various components.

These components are called hardware. Hardware consists of input, output, storage (memory) devices. These devices have been explained below:


The data is fed into computer with the help of input units.

keyboard input device

Keyboard Hardware of Computer

Keyboard is one of the most important input unit used for the purpose of input. Input unit is used to –

  • feed new data
  • remove the old data/ records – alter the data/making corrections

A keyboard which is just like a typing machine with modified functions. As soon as we press a key on the Keyboard, a character on the V.D.U. appears.

Magnetic disk, magnetic tape, Punch card reader, punched paper tape and floppy disk are hardware of computer are also used as input media. Mouse, Light Pen, Joystick and track ball are also popular input media.

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Hardware of computer – Mouse is a handy input device used for pointing. It has a long tail which is connected with mouse card.  It can be moved on a smooth surface i.e. table or mouse pad to stimulate the movement of cursor.

hardware component mouse

The cursor may be in the form of a shining arrow, which is called mouse pointer. The user can move the arrow in any direction i.e. from top to bottom or one corner to other corner diagonally on the screen in a flash.

Mouse is very useful like input device in Desk Top Publishing programs. Programs like Windows, PageMaker, Ventura, Corel­Draw, MS-Word etc. are very difficult to run without mouse.

It has push button which can be pressed to open some window or sub-window on the screen at a click.

It is very easier to control cursor movement with a practice of a few minutes.

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Joystick input

It is also a pointing input device which is used frequently in programs like video games and on personal computers. It is an electric device used like a mouse for controlling cursor movement.

It consists of four micro-switches arranged in four directions (East, West, North, South). When the joystick is moved in a particular direction, the switch is activated in that direction and gives a signal to the cursor.

The cursor moves in the direction in which the stick has been moved.

Light Pen

light pen

Light pen, as the name suggests is a pen shaped light-sensitive device and can be connected to a computer to draw graphics and to highlight the text directly on the computer screen.

It contains the light receptor and is activated by pressing the pen against the face of monitor.

When the pen is brought close to the screen, the light emitted by it modifies the data. The pen consists of a light-sending mechanism at the end of a pen.

Track Ball

Track Ball Input Device

This is also pointing device. It contains a ball which can be rotated in any direction.

The user moves the ball in the desired direction to move the cursor on the screen. Speed of spin is controlled by the electronic circuit. The instructed information is sent to the processor.


Printing devices are used for printing the processed information i.e. output. The output may be in the form of figures, images, charts etc.

This output can be printed by different types of printers. Different printers are used for different purposes.

Printers Varieties

  • Dot matrix printers
  • Line printers
  • Daisy wheel printers
  • Inkjet printers
  • Thermal matrix printers
  • Laser printers.

Voice and Speech Devices

A voice input system is one of the most exciting input system. This system accepts the human voices/speech so that it could form the input to computer directly without the movement of keys, mouse etc.

The spoken input is analyzed and matched with the pre-stored patterns to identify the input.

Voice recognition techniques are used to convert voice signals in appropriate words.



A scanner hardware of computer is an instrument which is used to scan a diagram, photograph etc. and the image can be brought on to the monitor.

When a scanner is used, light is ON in the scanner. The scanner is moved to and fro on the figure or a photograph. The image of the figure appears on the screen of the monitor. This image can be edited, and shaped into desired form.

While using the hand scanner, care must be taken that the hand remains uniform, otherwise the image appeared will not be free from defects.

For sensitive jobs, flat bed scanner is used. To use a scanner, a special software is required to be loaded in the computer. This software is generally available with the scanner.

Scanner document

Optical scanners are becoming very popular for the purpose of office automation. Scanners facilitate capturing of various photographs and pictures in graphic form and the images are stored in the computer.

As and when need arises, the image is retrieved on the screen of the monitor. Now-a-days, computerized bank branches are using scanners for storing the signatures and photographs of the customers.

Magnetic Ink Character Recognition (MICR)

Due to banking increasing habits of the people, there is tremendous volume of cheques being presented in the banks every day. To make this work easy, MICR system is used in banking applications worldwide.

This technique is in operation since last some years. In this method, the cheques are pre-coded and what is written on it is read by the machines.

The cheques can be read directly by the MICR reader, without the need of transcribing the data on punched cards of paper tapes. The requisite information is printed on the cheques with a special type of ink.

This ink is made up of magnetic material and when the cheque is inserted in the machine, the information printed on the cheque is magnetized and is read by the machine. This technology has become very popular world-wide.

Optical Mark Recognition Technology (OMR)

OMR technology permits the direct reading of any printed character. The computer is able to read the documents directly. The characters are read by optical scanners.

The major advantage of this technology is that no special ink is to be used. In this way, this technology is somewhat superior to MICR technology.

Area of use of OMR Technology

This technology is not widely used in India. However there are some areas where this technology is being used. This technology is useful for objective type questions.

Answers to objective questions are evaluated by these machines. Various Recruitment Boards are using this technology. The answer sheet contains ovals which are to be blackened by HB pencil.

The scanner of the machine reads the characters (black ovals) and compares them with correct answers and then it evaluates the questions. This technology is also used in survey of population and survey of markets.

Optical Bar Code Reader (OBR)

This device scans a set of vertical bars having different width for specific data. The devices are available as hand-held devices and are used to read merchandise in stores, library books, medicines etc.

Digital Camera

digital camera hardware component

Digital camera provides digital image of an object which is of high quality. It can be used like a simple camera to take photographs. These photographs can be displayed on the computer using some special image software which is generally made available with the digital camera by the manufacturer.

A digital camera can be connected with a computer even for videoconferencing. Digital camera has its in-built memory. The image is stored on the memory chips of the camera which can be downloaded into the computer.

On computer, the image can be edited in any desired formats. To edit the images/photographs, software like Photoshop, Core1DRAW, Photo Deluxe etc. can be used.

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Hardware of computer Output devices are those hardware devices which accept the results produced by the computer or processed output sent by the computer. These devices produce the results and reports in the readable form. Output devices mainly fall into two categories.

  • Devices that produce output that is understood by printers and me, tors.
  • Auxiliary storage devices that hold data which may be intended for further

Visual Display Unit

Video Display Unit is called monitor. This hardware of computer is an important hardware device since all the data being fed in the computer is displayed on the VDU screen. You can check the data for its accuracy and any mistake seen in the data entry, can be corrected through the keyboard.

Similarly if the result is just to be viewed, the same can be sent to the VDU. A monitor represents like a TV screen. It displays the graphics information generated by the computer through a card called video card.

The video card translates information that is coming from the computer into a form the monitor can understand. Information on a monitor is displayed in the form of pixels.

A pixels is the smallest element of the image. Resolution of the monitor screen means how many pixels it can accommodate in a given time. Resolution is determined by the number of pixels horizontally and vertically.

The typical resolution ranges from 640 x 480 pixels to 1024 x 768 pixels. The more is the resolution, the more accurate will be the image.

The size of the monitor is measured diagonally across the screen. Monitors are available in the size of 15″, 17″, 19″, 21″ and 25″ size. Three categories of screen displays are available

  1. Cathode Ray Tube (CRT)
  2. Liquid Crystal Display (LCD)
  3. Projection Displays

CRT Displays

monitor crt hardware of computer

The main components of a CRT monitor are the electron gun and a phosphor coated display screen with a electron beam controlling mechanism (electromagnetic field).

The quality of display is indicated by the resolution of the display device. There are different types of CRT displays.

  • CGA (Color Graphics Adapter)
  • MDA (Monochrome Display Adapter)
  • HGA (Hercules Graphics Adapter)
  • EGA (Enhanced Graphics Adapter)
  • VGA (Video Graphics Adapter)
  • SVGA (Super Video Graphics Adapter)

LCD (Liquid Crystal Display)

Lcd Monitor hardware component

The major advantage of LCD technique is the low energy. LCD screens are commonly used in portable devices because of their compactness and low energy requirements.

Projection Displays

The personal size screen of the displays are replaced by the large screens upon which images are projected. These are normally used for large group presentations.

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Printers are the output devices. The data/information from the main memory of computer is transferred to the memory of printer and the same is printed in the form of output.


The data can be printed in the form of graphs, letters, reports etc. as desired by the user. Printers are mainly divided into two Categories.

1. Impact Printer             2. Non Impact Printer

Impact Printer

Hardware of computer Impact Printers use ribbon/ carbon papers to leave an impression on the paper. Dot matrix printer, Line printer and Daisy wheel printer come in the category of Impact Printer.

Dot Matrix Printer

dot matrix printer

Dot Matrix Printer leaves the impression of character in the form of dots. This printer consists of a hammer which prints the characters one by one. Output is obtained in the form of dots. This printer is widely used with Personal Computers.

The hammer of the head contains 9 pins or 24 pins. The typical speed of dot matrix printer is 40 characters per second to 1000 character per second.

Line Printer

Line Printers are called so because these print one line at one time. The speed of line printers is measured in terms of printing of lines per minute. These printers cart work on a large amount of data printing for a quite longer duration of time.

The hammer of this printer prints the character with the help of ribbon. The speed of line printer is wonderful and they can print 300 to 2500 lines in a minute. The  width of the line is 15 inches and the line has 96 to 160 characters. Chain Printers and drum printers come in the category of line printers.

Chain Printer

In a chain printer, a chain of characters rotates and in this process hammer of the printer strikes on chain and the character of the chain leaves an impression of the character on the paper. This printer can work for a longer time but the quality of output is not so good.

Daisy Wheel Printer

This printer contains a disk of metal or plastic and it has 96 characters on its petals. This disk is capable of rotating. The hammer of this printer pushes the character and it leaves an impression of the alphabet on the paper.

Typical speed of daisy wheel printer is 20 characters per second to 100 characters per second. Daisy wheel printers can not be used for longer duration and also they are slow in functioning. The main feature of this printer is that the printing is of superior quality.

Non-Impact Printers

Laser Printer

These printers generate both graphics as well as text as image outputs. The quality of output is very good. These printers use the technique of laser and photocopy.

The speed of this printer is marvelous. It can print more than 300 pages in one minute. It can print a normal book only in one minute. With the development of technique, Laser Printers now, can print multicolored graphics/output. As the quality of the output is very good, laser printers are used in Desk Top Publishing.

The main limitation of laser printer is that it is very costly. Only large institutions and professionals can afford its installation and maintenance cost.

Thermal Matrix Printers

This is another type of non-impact printers. These printers work on heating arrangement. Special type of paper is needed for printing.

It contains print wires and when electricity is passed through these wires and with passage of current, the wires get heated and leave impression with the help of special type of ribbon. These printers are slow and costly.

Inkjet Printer

Inkjet printer is a new development in non-impact printers. These printers do not make a noise while printing. The drops of ink appear in the form of character. Small pumps release tiny drops of ink through nozzles onto the paper in the form of character.

The printing of this printer is good and a good quality of graphics can be obtained. The speed of Ink Jet Printer ranges between 50-300 characters per second. The shaped of these printers is very less as compared to laser printers.


Plotters are output devices and are used for various purposes like graphics, diagrams etc. There are different types of plotters and are used for various purposes.

  • Graph Plotter                                     
  • Flat Bed Plotter                                     
  • Drum Plotter

Graph Plotters

As evident from its name, graph plotters are used in graphic work and diagrams. Plotters are of mainly two types

  • Flat Bed Plotter                       
  • Drum Plotter

Flat Bed Plotter

This plotter uses a light pen and draw graphs on the papers. Multicolored pens are used for graphics. Pen is controlled by pen holder. To draw a colored diagram or graph, pens of 8-10 colors are used.

This plotter is also known as LIGHT PEN PLOTTER. It can make graphs of small to large size depending upon the size of Bed.

Drum Plotter

Drum plotter (printer) contains a drum which is cylindrical in shape. The drum is capable of rotating. Drum Plotter plots the graphs on paper by rotating. Normally a line in printed output contains 132 characters and this can print 600-2000 lines per minute. These plotters are very costly and are not used widely.


There is hardly any computer application which does not requires storage space. The data is stored for using in future. The auxiliary or secondary storage devices supplement the main memory.

They can store programs, data as well as output. This storage unit acts as input and output to the computer. Secondary storage devices hold the programs and data permanently.

Characteristics of Secondary Storage Devices

  1. High storage capacity. The secondary storage devices can store enormous amount of data. This capacity may be in terabytes.
  2. Access time. The time required to retrieve the data is very small. It may be in nanoseconds (billionths of a second).
  3. Data transfer rate. The data transfer rate (into or out) is very fast. They can send information to output devices in billions of bits per second.


Floppy Disk

floppy disk hardware of computer

Hardware of computer – Floppy disk is a recent development in storage devices. It was developed in 70s. This is very small storage device which can be used both as input and output medium.

This is made up of elastic plastic material and is finely coated with magnetic oxide. This disk is placed in plastic cover to avoid damage. The floppy is available in three standard sizes of 8″, 5.25″ and 3.5″. The storage capacity of each floppy disk is different.

So to select a floppy, the amount of data to be stored is taken into consideration. These days floppies of 3.5 inch size of 1.44 MB capacity are most frequently used and other two types have been outdated now.

Floppy SizeStorage Capacity
8 inches


5.25 inches

3.5 inches

250 KB to 1.5 MB (Outdated)


125 KB 1 MB (Outdated)

1.44 MB


Features of Floppy Disk

  1. It is a small storage medium and can be easily taken from one place to another.
  2. It is cheap storage medium.
  3. It is very useful for Personal Computer.
  4. It can be used both as input and output medium.
  5. It can be used for reading and writing.
  6. It is very useful for small commercial houses.

The floppy is inserted into floppy drive. This rotates inside the floppy drive like a musical record and the data is stored on fine circular paths called tracks. The data already stored in it can be removed and new

data can be fed in place of it. The capacity of floppy disk depends upon the following factors :

  • Design
  • Density
  • Surface

Number of tracks

In some floppies both surfaces can be used, hence the storage capacity is doubled. If more is the density and number of tracks on the floppy, more is the storage capacity.

Formula for calculating storage capacity of the floppy :

Capacity =N  x  n  x  s  x  d

Where N = Number of tracks, n = Number of sectors

s = Number of sides, d = Data capacity


Magnetic Disk (Hard Disk)

Magnetic Disk resembles a record player. This is very useful and one of the most popular storage devices hardware of computer . The data stored onto it can be searched out very quickly and we have not to pass through the data sequentially.

In this way the magnetic disk has an edge over magnetic tape. Magnetic disk pack consists of 6 or more than six disks which are elastic in nature. The material of the magnetic disks is made up of plastic.

These disks rotate on one another in a spindle. The distance between each magnetic disk is 0.5 inch and these rotate at the rate of 60 or more rotations per second. Disks can be used from both surfaces.

The surface of a magnetic disk is finely coated with magnetic oxide which gets magnetized very easily. The disk surface contains circular paths called tracks and each track is divided into a sector.

The data can be stored equally in each track. The size of the tracks is smaller as compared to outer tracks. packing density of the tracks is different. The tracks near to the center of the dis have more packing density and the tracks away from the center (large in size) have lesser packing density.

The storage capacity of the disk depends upon the following factors :

  • -Packing Density
  • -Number of surfaces
  • -Number of tracks each surface
  • -Number of sectors in each track.

A standard magnetic disk contains 400 to 1600 tracks and the standard size is 14 inches. Disk can store 0 to thousand kilobytes of data. These days hard disks are available in the storage capacity of 2 GB, 10 GB, 20 160 GB, 200 GB, 250 GB etc.

Terms Related With Magnetic Disk

  • Cylinder : Cylinder is a major sub-division of a disk. Each disk is considered as a combination of these cylinders. The number of cylinder on a disk is equal to the number of tracks on it.
  • Seek Time : As soon as the read/write command is given, the read/write heads are positioned on the specified track number by moving the arm in the direction of specified track number. The time required to position the head over the specified track is called seek time.
  • Latency Time : When the read/write heads are positioned on the specified track, the head on the specified track is activated. The disk is continuously moving. The head waits for the desired data to come under it. The time required to spin the needed data under the head is called latency time.
  • Access Time : The total of Seek Time and Latency Time is called access time.

 Access Time = Seek Time + Latency Time

The average access time for most disks is ranging from 10 milliseconds-100 milliseconds.

Comparison between Floppy and Magnetic Disk (Hard Disk)

  1. The storage capacity of magnetic disk is much more than that of Floppy Disk.
  2. More than one program can be done on the magnetic disk in a given time.
  3. A large amount of data can be stored even on one magnetic disk.
  4. The access time in magnetic disk is less than that of floppy disk.
  5. Hard disk is costlier than a floppy disk, but is widely used due to its features.

Magnetic tape

Magnetic tape hardware of computer is a storage device in the form of plastic ribbon (tape) which is rolled on a reel. This tape is similar to a tape recorder cassette. The ribbon of this device is made up of plastic material and a fine coating of magnetic oxide is done on the tape.

This oxide is magnetized very easily. When we feed data in a tape, this is recorded on the tape as magnetic spots. Normally the length of the tape in a tape reel is 2400 feet and its standard width is 1/2 inch.

A text book of 400 pages with 50 lines per page and 40 letters per line can he accommodated in less than 15 feet of tape of density 6250 bpi. The storage capacity of a tape depends upon the following factors :

  • Tape density -Length of tape
  • Blocking factor -Inter Block Gap

Features of Magnetic Tape

  1. it is a cheap storage medium.
  2. Large amount of data can be stored on it depending upon the length.
  3. Data can be transferred easily from one computer to another.
  4. Errors of information written on it can be easily removed/amended.
  5. Magnetic tape is easy to use.

Besides its features, magnetic to has one defect. There is some gap between two records and a large amount of tape is wasted in this way. But this gap is of significant importance.

During read/write time some tape moves ahead, hence some gap left between two records. This gap is called INTER RECORD GAP. This gap is different in different tapes. Some times it is 0.5 or 0.6 inch.

To avoid wastage of the tape, a special method, called blocking, is used. Some records are grouped and a block is created. For example if 20 records are grouped to form a block then the Blocking factor is said to be 20.

There is some gap between two blocks and this is called INTER BLOCK GAP (IBG). While selecting a magnetic tape, blocking factor is taken into consideration.

Winchester Disk

This storage device is also a recent development and very useful for storage of data. This disk is better than floppy disk or hard disk because it is sealed in air-tight box. Air, dust particles and other harmful elements cannot enter into the had and this disk remains quite safe.

This disk contains many tracks and the packing density of these tracks is very high. A large amount of data can be stored in this disk. The data on this disk can be written/read at a very fast rate.

Standard size of the Winchester Disk

(1) 5.25 inches         (ii) 8 inches       (iii) 14 inches

Depending upon the size, the storage capacity of the Winchester disk is different. The capacity may vary from 10 MB to 500 MB and even more.


Optical Disk

This is a recent development in the storage devices. Optical disk • is also called Compact Disk (CD-ROM). The storage capacity of an optical disk is wonderful.. The diameter of this disk is 12 cm. and it can store 680411.3 of data.

Today optical disks are available which can store even more than 680 of data. This is very fast and cheap storage device. An amazing fact about optical disk is that a single disk is equivalent to 1000 floppy disks.

The data/information on the optical disk cannot be removed/altered. The data is stored permanently on the optical disk. These days CD writers have been made available which can also write the information/data on CDs.


dvd hardware of computer

DVD has full form as Digital Versatile Disk. You have learnt above that a single CD can store a large amount of data on it. Sometimes even a CD is not sufficient to write a complete program/information on it.

For example: a complete movie has to be stored on 2 or 3 CDs. Some softwares need more than one CD for recording. To eliminate this limitation, DVD-ROMs are used.

Physically a CD and a DVD look similar but the storage capacity of a DVD is 25 times more than a CD. A DVD can store up to 4.7 GB of data. The quality of a DVD is better than CD. DVD drive is generally called DVD Player.

The drives are data transfer speeds of 40X. DVD drive can also read a CD-ROM.



Flash memory is non-volatile computer memory that can be electrically erased and reprogrammed. It is primarily used in memory cards and USB flash drives for general storage and transfer of data between computers and other digital products.

It is a specific type of EEPROM (Electrically Erasable Programmable Read-Only Memory) that is erased and programmed in large blocks; in early flash the entire Chip had to be erased at once.

Flash memory costs far less therefore, has become the dominant technology wherever a significant amount of non-volatile, solid-state storage is needed.

Example applications include laptop computers, digital audio players, digital cameras and mobile phones. It has also gained popularity in the game console market.

Flash memory is non-volatile, which requires no power to retain the information stored in the chip. In addition, flash memory offers fast read access times and possess better shock resistance than hard disks.

These characteristics explain the popularity of flash memory in portable devices. When flash memory is packaged in a memory card, it is enormously durable, being able to withstand intense pressure, extremes of temperature and even immersion in water.

Pen Drives

pen drive memory

Pen Drives are referred to as thumb drives. Pen drives are faster than downloading data via e-mail. A pen drive can transfer large volumes of data from :

  • laptop to laptop
  • desktop computer to laptop
  • laptop to a desktop computer.

Pen drives make accessing and transferring audio video files very easy with the USB plug-and-play interface.

USB pen drives provide dependable data, music an video transfers, and storage with plug and play ease. No driver software is needed for connecting pen drive.

Therefore, a pen drive can be put to use immediately as and when needed by the computer user. With no batteries, no software and no cables, a pen drive is totally portable.

Advantages of pen drive

  • It is portable.
  • It is light weight.
  • It is very compact.
  • It has a storage capacity ranging from 16MB to 32 GB.
  • It can transfer data at a very high speed.

Thanks for Reading….

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An aspiring BCA student formed an obsession with Computer/IT education, Graphic Designing, Fitness, YouTube and Blogging, and Helping Beginners to learn these skills and implement them in their life.

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