Input and output devices
Classify devices by the direction in which information moves and recognise equipment that can perform both input and output roles.
Follow the direction of information#
The simplest way to classify a device is to ask which way information moves.
- Input moves data or commands into the computer.
- Output moves processed information out of the computer for a person or another system to use.
The words in and out are described from the computer's point of view.
Common input devices#
Keyboard and pointing devices
A keyboard enters characters and commands. A mouse or touchpad sends movement, selection, and scrolling actions.
Microphone and camera
A microphone converts sound into data. A camera captures light as digital images or video.
Scanner and sensors
A scanner captures information from a document or object. Sensors can provide measurements such as temperature, movement, or light level.
Common output devices#
Monitor
A monitor displays text, images, and video produced by the computer.
Speakers and headphones
These devices convert digital audio signals into sound a person can hear.
Printer
A printer produces physical output on paper or another material.
Devices with both roles#
Some equipment cannot be placed in only one category.
A touchscreen displays output and also receives touch input. A network interface sends and receives data. A storage device accepts data when files are written and provides data when files are read, although introductory classifications often place it in a separate storage category.
Classify the interaction#
The same device can have different roles during different actions. When a touchscreen displays a map, it provides output. When a user taps a location, it receives input.
This interaction-based method is more reliable than memorising one label for every device.
Common mistakes#
Using the user's point of view
A speaker sends sound to the user, but it receives information from the computer. It is therefore an output device.
Confusing storage with input
A storage drive can supply data to the processor, but its main purpose is retention. Basic computer models usually discuss storage separately from user input devices.
Assuming a wireless device has no input or output role
The connection method does not change the role. A wireless keyboard remains an input device.
A quick test#
Complete the sentence “The device sends information ___ the computer.” Use into for input, from for output, and both ways for a combined device.
Key points
- Input devices send data or control signals into a computer system.
- Output devices present processed information to a user or another system.
- Some devices, including touchscreens and network interfaces, handle both directions.
- Classify a device by its role in a specific interaction, not only by its appearance.