Different Types of Input Devices


            Hard disks and Diskettes must be formatted before saving data on them. Formatting can be considered as an initialization process that prepares the disk or diskette electronically so that it can store data or programs.

Input Devices

            Input devices enable data to be fed into the computer in a form that the computer can use. Input devices are categorized into two types: keyboard entry devices and direct entry devices. A devices through which data can be entered to the computer by pressing keys is called a keyboard entry device whereas all the other types of input devices are called direct entry devices.


The keyboard is the most commonly used input device and has been used since computers were first introduced. They are intelligent devices and contain their own chips. Each key is switch, which closes when that particular key is pressed. The microprocessor scans the keyboard hundreds of times a second to see if a key has been pressed; if it has, a code that corresponds to that key is sent to the Processing Unit. The CPU then translates this code into the ASCII code (the code that computers use to represent characters on the computer keyboard), which is then used by the computer program.


A mouse is another popular input device that forms an essential part of a computer system. Its movements on the desktop are translated into digital information, which in turn is fed to the computer, causing the cusor to move on the screen. Underneath the mouse there is a ball which rotates when the mouse is moved by the user and sensors pick up this movement. A mouse usually has two or three buttons, and these are used to make selections on the screen. The Mouse is classified as a pointing device. Joysticks, Touch Screens and Light pens are a few other examples for pointing devices.

          A newer type of mouse is the optical mouse. An optical mouse uses a light-emitting diode (LED), an optical sensor, and a digital signal processing (DSP) in place of the traditional mouse ball and electro-mechanical transducer. Movement is detected by sensing changes in reflected light, rather than by interpreting the motion of a rolling sphere.

Digital Camera

              Digital Cameras store the images digitally rather than on film. Digital still cameras can be connected to a computer and the pictures taken on them can be transferred while digital motion cameras or web cams can be used to create video and for video conferencing purposes.


            A microphone can be used to record sound into a computer. Microphones are also used for voice communication through a computer, for example, for making telephone calls through a computer.


            Scanners are input devices normally used to scan text or pictures. The scans are then stored in a computer's memory where they can then be accessed and modified using a desktop publishing package, before being printed. Both black and white, and color scanners are available.
            Scanners often come with OCR software. Optical Character Recognition (OCR) is where the text on a page is scanned and then converted and fed into a word processing package so that it can be modified according to the needs of the user. OCR software may not recognize certain characters, be they handwritten, typed fonts or symbols.

Other Devices 

           A variety of devices exist which allow people to input different kinds of information into a computer. Some such devices are:

  • Fingerprint Reader - Used to capture a fingerprint of a person into the computer.
  • Magnetic Ink Character Recognition (MICR) - Used to recognize characters printed in special ink. e.g. on cheques.
  • Environment Sensors - Movement, Temperature, Humidity, etc., can be monitored through a computer using these devices.


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