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Input devices

An input device allows data such as text, images, video or sound to be entered into a computer system.

• Keyboard - The most common input device used for entering text. Includes keys for word processing and data inputting, and for performing specific functions.
• Mouse - The most popular pointing device used to control the cursor on the screen and activated when moved across a flat surface. There are usually two buttons that activate different features on the screen.
• Microphone - Used to convert analogue sound waves into a digital form that can be saved and manipulated by the computer. A microphone can also be used to input voice commands but they do not work well in noisy environments.
• Scanner - Works in a similar way to a photocopier. Captures images from the source which are then converted into a digital form that can be stored.
• Assistive technology - Devices that are used by some people with disabilities to access computers. For example, a sip/puff tube can be used by someone with a disability such as paralysis to control a computer system.

Output devices

There are many outputs created by a computer system. These include printed documents, on-screen data and sound. An output device allows data to be transmitted by the computer in a human-friendly form, for example, sound being played through a speaker.

• Monitor - The main output device of a computer. It forms images by converting electrical energy into light in the form of tiny dots on the screen called pixels. The sharpness of the image depends upon the number of pixels.
• Printer - Used to print information on paper. Commonly uses either lasers or inkjets to precisely place ink onto the page to recreate text and high-quality images.
• Speaker - Converts digital signals into audible sound waves.
• Projector - A device that is used to project video output from the computer onto a wall or screen.