How do you get data to the CPU? How do you get information out? Here we describe one of the most important places where the computer interfaces with people. We input text, music, and even speech, but we probably never think about the relationship between what we enter and what the computer processes. People understand language, which is constructed of letters, numbers, and punctuation marks. However, computers can understand only the binary machine language of 0s and 1s. Input devices are essentially translators. Input devices translate numbers, letters, and actions that people understand into a form that computers can process. Have you ever wondered how information processed by the system unit is converted into a form that you can use? That is the role of output devices.

While input devices convert what we understand into what the system unit can process, output devices convert what the system unit has processed into a form that we can understand. Output devices translate machine language into letters, numbers, sounds, and images that people can understand.

Competent end users need to know about the most commonly used input devices, including keyboards, mice, scanners, digital cameras, digitizing tablets, voice recognition, and MIDI devices. Additionally, they need to know about the most commonly used output devices, including monitors, printers, and audio output devices. And end users need to be aware of combination input and output devices such as fax machines, multifunctional devices, Internet telephones, and terminals.