Input and Output Devices

Before a computer can get to work solving a problem, it must be given the program and the data if there is any. After it has found the solution, the computer must communicate this solution to the human beings who posed the problem in the first place. The topic of getting information into and out of computer is called input/output or usually just I/O.

Input/output devices are used for communication with the computers. Thousands of kinds of I/O devices are available today and the number is growing rapidly. A few of the more common ones are listed below:
- Keyboards
- Printers
- Scanners
- Pen and ink plotters that draw graph
- Computer mouse
- Microphones
- Speakers
- Electric light pen

I/O Processors

Some I/O devices can transmit a large amount of data in short time. If the CPU had to process every character separately, much CPU time would be wasted. To avoid tying up the CPU for long periods of time on I/O, most of the computers have one or more specialized, low-cost I/O processors. Because the I/O is performed by these special processors, the CPU is available to spend most of its time on more difficult computations. The I/O processors can run in parallel with the CPU. In other words, while the CPU is busy in computing, the I/O processors can be doing I/O.

Input Devices

A variety of input devices exist to convert information in any form (data, text, voice or image) into binary pulses recognized by computers.