Input and Output Devices of a Computer

Input-Output Devices

Input output devices act as an interface between the user and the computer. A device sends information to a computer system for processing is called as input device and a device that receives and then reproduces or displays the results of that processing is called an output device. Most devices are either input devices or output devices, because they can only accept data input from a user and forward the same to the computer system or receive the output data from computer. There are some devices which are capable of both accepting input and handling output, these types of devices are called as I/O devices (input/output devices). Input-output devices are also called as peripherals. Now let us discuss about various input output devices.

Input Devices

Input devices can send data or information to a computer or another device. Input devices cannot receive data or signal from some other devices. Various input devices are as listed below:

  1. Keyboard: It is an input device which sends data in to the computer. The data send depends on the key pressed by the user.
  2. Mouse: A mouse is a small handheld input device which controls a cursor in a graphical user interface. It can move and select text, files, folders etc. on our computer according to the user input.
  3.  Microphone: it receives audio generated by some input source and sends the same to a computer.
  4. Webcam: it sends the captured images to a computer.
  5. Graphics Tablets: This input device is used to draw using hand.
  6. Trackballs: trackball is an upside down mouse which is encased within a socket. It is a cursor control device.
  7. Barcode reader: It is used to read the barcode of various items and feed the same to computer.
  8. Gamepad: Also known as joy pad is the input controller for video games.
  9. Joystick: these input devices are used to control video games.
  10. Scanner: Scanner optically reads and document, file or image and then changes it into digital signal and sends to the computer.
  11. Electronic Whiteboard
  12.  OMR: optical mark recognition/ reader, is used to read marks on a document and send them to computer.
  13.  OCR: OCR stands for optical character Recognition, is an input device which reads printed text and sends that to computer.
  14. MICR: Magnetic Ink Character Reader is an input device which generally finds application is banks to process cheques.

Output Devices

A device that can receive data from computer or another device and create output with that data is called output device. Examples of various output devices are as :

  1. Monitor: A monitor is an output device that is responsible for receiving data from a computer and displaying that information as text or images for users to see.
  2. Projector: Gets data from a computer and displays or projects the same information onto a screen or a wall. Projector cannot directly accept data from a user and send that data to another device.
  3. Speakers:  Receives sound signal from a computer and then plays that sound signal and thus we hear songs or music or any other audio.

Both Input / Output Devices

An input/output device is capable of receiving data from users or another devices and also sending data to another devices or computers. That means a devices which can be used as both input device and output device are called Input / Output (I/O) devices. Some examples of input/output devices are as:

  1. USB drive: Also known as pen drive or flash stick works as both input device to computer and as an output device. USB drives receive or save data from a computer as an input and it can also send data to a computer or another device.
  2. Modems:   It is used to transmit and receive data from one computer to another computer or other devices using telephone lines
  3. CD-RW drives and DVD-RW drives: Receives data from a computer as input to copy onto and save into writable CD or DVD.  We also use CDs or DVDs to transfer data to a computer.
  4. Touch Screen: Touch screen is both input and output device. By touching the screen input is provided and being a screen, it is used as an output device.
  5. Headsets: Headset consists of speaker as an output device and microphone functions as an input device.
  6. Facsimile: Facsimile or FAX machine has a scanner which is an input device and a small printer to provide output.


Input and output devices are integral part of a computer. We cannot interact with a computer in absence of I/O peripherals. Think of a situation if you have to interact with computers without I/O peripherals. Do you think it is possible?    

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