Hardware Devices: Input and output devices

PAPER 2 - ⇑ External hardware devices ⇑

Input and output devices Input devices →

You should already have met the internal components of the computer and the peripherals, that sit outside. We are now going to look at two different categories of peripherals. Those that input data into a computer, and those that output data from the computer.

Computers work along the lines shown above, they receive inputs (instructions etc.), they process the input working out what to do with it, then they output some form of result

How do we tell what is an input and what is an output device? Think about it from the computer's perspective. If a device is putting data into the computer in the form of text, sound, images, button presses etc. then it is an input device, if the device is outputting things from the computer such as sound, movement, printing, images etc., then it is an output device. It really is that easy to tell the difference, but be warned, some devices can be both input and output!

Let's take a look at two examples:

Example: Telling the difference between input and output devices
An LG LCD monitor

When you are using the monitor it displays things that you are doing, such as moving windows and clicking on website links. At no point do you click on the screen or put anything into the monitor. The only thing it does is output information, therefore it is an output device. Easy!

An optical mouse

A mouse is used to move a little cursor around the screen, clicking and dragging as you go. if you let go of the mouse, the cursor will stop. The computer is relying on you to move the mouse, the mouse won't move on its own! Therefore it is an input device.

Exercise: Input and output devices

Note whether the following devices are input or output devices (or both!)

  • Printer
  • Mouse
  • Keyboard
  • Monitor
  • Web cam
  • Scanner
  • USB thumb drive
  • Graphics tablet
  • Joypad
  • Speakers


  • Printer - output
  • Mouse - input
  • Keyboard - input
  • Monitor - output
  • Web cam - input
  • Scanner - input
  • USB thumb drive - input and output (read and write!)
  • Graphics tablet - input or output (if there is a screen on it)
  • Joypad - input (output as well if it rumbles!)
  • Speakers - output