In computer input unit is defined as an input device, a piece of computer hardware apparatus used to supply a data processing system including a computer or information device with control and data signals.
Examples of input device: Mouse, keyboards, scanners, joysticks, and digital cameras.
An output device is any device that is used to transmit a computer’s data between devices or client. The bulk of computer output data designed for people is in audio or video format.
Examples of output device: Projectors, monitors, microphones, printers and headphones.
A piece of hardware that handles all the instructions of a computer program is the CPU (central processing unit) of a computer. It performs a computer system’s basic logical, arithmetical and input/output functions.