Cambridge IGCSE 0478 · Topic 3 · 3.2a

Input
Devices

Keyboard · Mouse · Touchscreen · Scanner · Sensor · Microphone

CSZoneCambridge IGCSE Computer Science 0478

Common Input Devices

Sending Data to the Computer

Keyboard: text and command input. Each key press sends an ASCII/Unicode code. Most widely used input device.

Mouse: pointer device. Optical sensor detects movement. Buttons for selection and right-click menus.

Touchscreen: detects finger position (capacitive or resistive). Used on smartphones, tablets, ATMs, kiosks.

Microphone: converts sound waves into electrical signals for voice input, video calls, speech recognition.

Scanning & Imaging Devices

Capturing Documents and Codes

Flatbed scanner: digitises paper documents and photographs. Light reflected from the surface is detected by a CCD sensor.

Barcode reader: laser scans the barcode pattern. Used in supermarkets, libraries, warehouses. Barcodes store product codes.

Digital camera: CCD/CMOS sensor captures images. Used in CCTV, mobile phones, medical imaging.

Sensors & Specialist Devices

Automated & Specialist Input

Sensors: temperature, pressure, light, humidity, motion — convert physical measurements to digital signals. Used in control systems.

Biometric readers: fingerprint scanners, facial recognition, retina scanners — used for security and authentication.

Graphics tablet: artist draws on a pad; stylus position is tracked precisely. Used in design and illustration.

RFID reader: reads passive RFID tags — used in contactless payments, library books, animal tracking.

Exam Practice

Have a go at this question

Cambridge IGCSE 0478 style

A greenhouse management system monitors temperature and humidity automatically. State two appropriate input devices and explain why each is suitable.

4 marks

Temperature sensor [1] — continuously measures temperature and converts it to a digital signal for the computer to act on [1]. Humidity sensor [1] — measures moisture in the air so the system can control irrigation automatically [1].

Key Takeaways

What to Remember

Keyboard, mouse, touchscreen: manual user input devices

Scanner, barcode reader, camera: capture physical documents/images/codes

Sensors: measure physical world automatically (temperature, pressure, light, etc.)

Always justify: match the input device to the specific use case in exam questions