Input and Output Devices

Every computer system follows the same three-step pattern: data goes in, it is processed, results come out.

Input devices are hardware components that take data or commands from the outside world and feed them into the computer.

Output devices are hardware components that take processed results from the computer and present them to the user (or the environment) in some understandable form.

A computer with neither input nor output devices would be useless: it could process data, but no one could give it new data and no one could see what it had produced.

This topic covers:

• The most common general-purpose input devices (keyboards, mice, scanners, cameras, microphones).
• The most common general-purpose output devices (monitors, printers, speakers, actuators, 3D printers).
• Sensors: specialised input devices that measure physical properties of the environment.
• Two comparison-style topics that appear regularly in exams: printer types (inkjet, laser, 3D) and touch-screen types (resistive, capacitive, infrared).