Data and instructions must be entered into the computer in order for computations to be carried out. The task (data-entry) is carried out by input devices. Data read by input devices are of different forms depending upon the form of input. Regardless of their type, all input devices provide data to emory in the binary form (in 0s and 1s). Input deices, therefore, perform the following basic functions:
1. Accept data from the outside world.
2. They convert data into binary form so as to make it understandable by the computer.
3. They send data in binary form to the computer for further processing.
The keyboard, joystick, light pen, scanner, touch screen, mouse, magnetic disk and floppy disk are some popular input devices.
This unit of the computer system provides the result of computation to the outside world. Its job is opposite to that of the Input Unit. Since a computer works with binary code, the result produced by it is also in binary form. This has to be converted to a human acceptable form to enable the results to be supplied outside. This task is carried out by the output units. an output unit, therefore, performs the following functions:
1. Accepts results produced by the computer in binary coded form.
2. It converts the coded data into human acceptable form.
3. Supplies converted results to the outside world.
A few examples of output devices are monitors (visual display units), printers, plotters, speech symthesizers and microfilm or microfiche.