Input devices
An input device lets a user or the environment send data into a computer for processing. Common examples include the keyboard and mouse, a touch screen, a microphone for sound, a digital camera or scanner for images, and a range of sensors such as temperature, light or motion sensors used in automated systems. Sensors are important because they let a computer collect real-world data continuously without a person typing it in.
Output devices
An output device presents the results of processing to the user or acts on the physical world. Examples include a monitor or screen, a printer (inkjet or laser) that produces hard copy, speakers for sound, and actuators that move parts in a control system. A device such as a touch screen can be both an input and an output device.
Example
In a greenhouse control system, a temperature sensor is the input device. When it becomes too hot, the computer sends a signal to an actuator (an output device) that opens a window.
Choosing the right device
The best device depends on the task, the environment and cost. A laser printer suits high-volume text, while an inkjet suits photos at home. A touch screen suits a public information kiosk where a mouse would be easily damaged.
Remember
- Input = data goes in; output = results come out.
- Sensors are input devices; actuators are output devices.
- A touch screen is both input and output.