Input and Output Devices
Hardware
| Device | What it does | Typical uses |
|---|---|---|
| Keyboard | Lets the user enter text and commands by pressing labelled keys | Typing documents, data entry, software control |
| Mouse (optical / mechanical) | Tracks hand movement on a surface to move a cursor; left/right buttons let the user click and select | Pointing, clicking and selecting on a desktop interface |
| Microphone | Converts analogue sound waves in the air into a digital signal | Voice calls, voice recognition, recording, online meetings |
| Digital camera | Captures a 2D image (or a stream of images) as a digital file | Photography, video conferencing, webcams, smartphones |
| Barcode scanner | Reads the parallel-line pattern of a barcode and converts it to a number | Supermarkets, warehouses, libraries |
| QR code scanner | Reads the 2D dot pattern of a QR code and converts it to text or a URL | Smartphone apps, marketing, contactless menus |
| 2D scanner | Captures a flat 2D image of a document or photo | Digitising paperwork, archiving, photo editing |
| 3D scanner | Captures the 3D shape and dimensions of an object | Reverse engineering, design, medical imaging, custom prosthetics |
| Touch screen | Combines a display with a touch-sensitive overlay, allowing the user to point and tap on the screen itself | Smartphones, tablets, ATMs, kiosks, modern monitors |
| Sensor | Measures a physical property (light, temperature, motion, etc.) and converts it to a digital reading | Monitoring and control systems (see section 5) |
A useful test for "input vs output": ask whether information is going into the computer (input) or out of the computer (output). A touch screen is both: the touch part is input, the display part is output.
Common exam question
Input and output devices built into a phone or smartwatch
Question: Give or identify two input devices, and one or two output devices, that are built into a mobile telephone, smartphone or smartwatch (3–4 marks in total, one per device).
Asked in 3 of the 17 papers, with the input and output halves always set together, one mark per device. For input, all three schemes credit touchscreen, microphone, digital camera, button and sensor, and a named sensor such as an accelerometer is accepted. The two phone schemes add a biometric device, and the mobile telephone scheme also lists keyboard and keypad. For output, the credited devices are screen, speaker, LED (or light) and actuator (a motor, which is what makes the device vibrate).
Keep the halves apart: the touch layer you tap is the input device and the screen you look at is the output device, so "touchscreen" earns an input mark while "screen" earns an output mark. Speakers, LEDs and motors belong on the output lines.
Exam tip
Name the type of device, not a brand
The mark schemes give no marks for the brand name of a piece of hardware, so always name the type of device: write "biometric device" or "fingerprint scanner", not "Touch ID", and "headphones", not "AirPods".