Input devices of computer

By | May 14, 2019

Input devices:

Any hardware devices used in the computer system that receives the data and information from the environment and sends them to the storage unit are called input devices:

An input system performs the following tasks:

  • It reads the data and instructions given by the user.
  • Then converts the accepted data and instructions in computer acceptable format.
  • Then finally it supplies the converted data and instructions to the computer system for further processing.

some commonly used input devices are: keyboard, mouse, trackball, joystick, touch screen, scanner, optical scanner, OCR, OMR, OBCR, MICR, etc.


A keyword is the most commonly used input device. Basically, it comes into importance when one has to type a document. For typing a document the keyboard has a set of alphanumeric keys and some functional special symbols and control keys.

pic: keyboard


Mouse is a most commonly used pointing device which is adjustable in our hand and moved across a small flat surface.The cursor moves on the computer screen according to the movement of mouse on the flat surface. It has two click buttons: left and right click. an icon on the screen is selected by a single click and opened by double click.

fig: mouse


A trackball is a pointing device similar to the mechanical mouse except it has the roller ball placed on the top of mouse. To move the cursor of the screen it is not necessary to move the trackball. As the whole device need not be moved for moving the cursor on the screen trackball requires less space then a mouse and is often built into the keyboard.Trackballs built into the keyboard are commonly used in laptop computers.

fig: trackball


joystick is also a pointing device that is used to move the cursor on the screen. its function is similar to mouse and trackball. it is mostly used in computer gaming. A joystick device consists of a stick with a ball at its lower end and a click button at its upper end. The stick is placed in a socket. The stick can be moved in different directions to move the cursor on the screen in desired direction. The click button mounted on the stick is clicked to select an option on the screen.

fig: joystick

Touch Screen:

Touch screen is the most popular and widely used input device today. A touch screen is sensitive to a finger. The user can easily select the required option by just touching that. touch screen is widely used in devices such as mobile, computer, watch, GPS etc.

fig: touch screen


A scanner is an input device that provides us an easy input method. it is used to read and store images, printed and handwritten material, pictures directly into the computer. There is no need for manual entry. data read by a scanner can be edited by some special graphics program. Some important type of scanner are: Optical scanner and Magnetic link Character Reader.

fig: scanner

Optical Scanner:

Most of the information which is a typewritten, pencil marks, bar codes etc. can be scanned by the optical scanner. The optical scanner reads such information by employing light source and light sensors. The commonly use d optical scanners are OCR(Optical Character Reader), OMR(Optical Mark Reader), OBCR(optical bar code reader) etc.

Optical Character Reader(OCR)

A general scanner inputs a printed or handwritten material and store them as an image, thus it is not possible to do any word processing task on the input document, because the computer cannot interpret the stored document as letters, numbers, and special character. To overcome this limitation, a scanner is equipped with special software called OCR.

Fig: Optical character reader

Optical Mark Reader(OMR)

Any mark made by pencil or pen is detected by optical mark reader. Generally, in multiple-choice question-answer, several options are given and one has to choose the correct answer by marking a square or circle with a pencil or pen. Then the sheet is submitted to the optical mark reader Then optical mark reader reads the presence or absence of a mark.

fig: optical mark reader

Optical Bar code reader(OBCR):

Data coded in the form of lines are known as bar codes. The bar code represents alphanumeric data by a combination of adjacent bars bu varying their width and the spacing between them. They are used particularly for the unique identification of different products such as books and other goods. An optical bar code reader can read such bars and convert them into electrical pulses to be processed by the computer

fig: optical bar code reader

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