Computer Input Devices

Input devices are all those computer components that are used to enter/feed information into the computer system.

In other words, input devices are devices used in computers that bring data into a computer.

The prime purpose of input devices are to translate data and information from human-readable format into electrical impulses.

List of Popular Input Devices

Some of the major or popular input devices are given below:

  • Keyboard
  • Mouse
  • Scanner
  • Optical Mark Reader (OMR)
  • Light Pen
  • Trackball
  • Magnetic Ink Character Recognition (MICR)
  • Bar code reader (BCR)
  • Optical Bar Code Reader (OBR)
  • Optical Character Recognition (OCR)
  • Voice Input Systems
  • Digital Camera

Now let's briefly describe all the above listed popular input devices.


It is the most popular input device used to feed data/programs into the computer system. Keyboard contains keys such as alphabets (a to z), digits (0 to 9), special characters, function keys, navigation/arrows keys, and many more keys etc.

In keyboard that is attached to a computer system when a key is pressed then an electric signal is produced detected by an electronic circuit called keyboard encoder.


Mouse is the second most popular input device attached to computer.

It is a pointing device. You can also says that it as an electromechanical hand-held device.

Mouse is used in many ways such as:

  • to scroll
  • to select
  • to draw sketches or diagrams etc.
  • to perform right-click (pop-up menu)
  • to change Windows position
  • and many more


Now-a-days, it is also an important and popular input device, as it is able to enter information directly into the computer without typing. Therefore scanner provides faster and "as it is" data entry or accurate data entry and exact data entry.

Magnetic ink character recognition (MICR)

Magnetic ink character recognition (MICR) is a technology used to verify the legitimacy of originality of paper documents, especially checks.

Special link, which is sensitive to magnetic fields, is used in the printing of certain characters to the original documents.

Information can be encoded in the magnetic characters. The use of MICR can enhance security and minimise the losses caused by some types of crime.

Optical Mark Reader (OMR)

OMR stands for Optical Mark Reading or Optical Mark Reader. OMR is a system that gathers information by using a hardware device that detects a reflection or an absence of reflection from a card or piece of paper.

OMR enables the processing of hundreds or thousands of documents every hour automatically.


Trackball is similar to the upside-down design of the mouse.

The user moves the ball directly, while the device itself remains stationary. The user spins the ball in various directions to effect the screen movements.

Light pen

This is an input device which is used to draw lines or figures on a computer screen. It is touched to the CRT screen where it can detect raster on the screen as it passes.

Optical character reader (OCR)

It is a device which detects alphanumeric characters printed or written on a paper. The text which is to be scanned is illuminated by a low frequency light source.

The light is absorbed by the dark areas but reflected from the bright areas. The reflected light is received by the photocells.

Optical Bar Code Reader (OBR)

It stands for optical bar code reader which is used for reading bar-coded data. It is scans a set of vertical bars of different width for specific data and is used to read tags.

Bar code reading is done by a light pen or scanner connected to computer.

Optical Character Recognition (OCR)

OCR is the recognition of printed or written text characters by a computer. This involves photo scanning of the text character-by-character, analysis of the scanned-in image, and then translation of the character image into character codes, such as ASCII, commonly used in data processing.

In OCR processing, the scanned-in image or bitmap is analysed for light and dark areas in order to identify each alphabetic letter or numeric digit. When a character is recognised, it is converted into an ASCII code.

Special circuit boards and computer chips designed expressly for OCR are used to speed up the recognition process.

OCR is being used by libraries to digitise and preserve their Holdings. OCR is also used to process checks and credit card slips and sort the mail.

Billions of magazines and letters are sorted every day by OCR machines, considerably speeding up mail delivery.

Bar code reader (BCR)

This device reads bar codes and converts them into electrical pulses to be processed by a computer. A bar code is nothing but data coded in form of light and dark bars.

Voice Input Systems

This devices converts spoken words to M/C language. A microphone is used to convert human speech into electric signals.

The signal pattern is then transmitted to a computer when it is compared to a dictionary of patterns that have been previously placed in a storage unit of computer. When a close match is found, the word is recognized.

Digital Camera

It converts graphics directly into digital form. It looks like an ordinary camera, but no film is used therein, instead a CCD (changed coupled divide) electronic chip is used.

When light falls on the chip through the lens, it converts light waves into electrical waves.

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