📚 Knowledge Library — Topic 3.6A — Hardware

Input Devices

Understand how input devices collect real-world data and send it into the computer so it can be processed.

Start LearningWorked Example
1. Invitation

Computers need data from the outside world.

A computer cannot see, hear or feel the world by itself.

It needs input devices to collect data and send it into the computer.

💡 Remember: input means data goes into the computer.
Figure 1.1
Input Direction
Real world
↓
Input device
↓
Computer
2. Big Idea

Input devices are translators.

Input devices convert real-world actions, sounds, images or measurements into data the computer can process.

The computer then represents that data using binary.

💡 Big idea: input devices translate the real world into computer data.
Figure 2.1
Translation
Key press
Sound
Touch
Light
↓
Binary data
3. FutureLogic Bridge

Think of an interpreter at a meeting.

An interpreter listens to one language and translates it into another.

An input device does something similar. It takes real-world information and translates it into a form the computer understands.

💡 Bridge: input devices translate from the human world to the computer world.
Figure 3.1
Interpreter Model
Human action
→
Input device
→
Computer data
4. Common Input Devices

Different devices collect different types of data.

A keyboard collects key presses. A mouse collects movement and clicks. A microphone collects sound.

A touchscreen collects touch position. A scanner or camera collects image data. Sensors collect measurements such as light, temperature or proximity.

Input examples

Keyboard
key press
Microphone
sound
Sensor
measurement
Figure 4.1
Input Types
Keyboard ⌨️
Mouse 🖱️
Microphone 🎙️
Scanner 📄
Sensor 🌡️
5. Worked Example

Choosing an input device.

The best input device depends on the situation.

Question: Which input device could let a user speak to an ATM?

Context
ATM
User action
speaking
Device
microphone
A microphone is suitable because it inputs sound.
Figure 5.1
Context Choice
User speaks
↓
Microphone
↓
Computer input
6. Sensors

Sensors input measurements.

A sensor detects a physical condition and sends data to the computer.

Examples include temperature sensors, light sensors, pressure sensors, infra-red sensors and proximity sensors.

🎯 Exam Tip: if detecting a person nearby, use a precise sensor name such as infra-red sensor or proximity sensor.
Figure 6.1
Sensor Input
Temperature
Light
Pressure
Proximity
↓
Measurement data
7. Exam Tip

Always check the context.

Cambridge often asks for an input device for a specific device, such as a smartphone, tablet or ATM.

Your answer must be physically suitable for that device.

🎯 Exam Tip: a mouse may suit a desktop computer, but it is usually not the best input device for a smartphone or tablet.
Figure 7.1
Suitable Device?
Tablet
↓
Touchscreen ✓

Mouse ?
usually not best
8. Common Mistake

Do not give a generic answer.

Students sometimes name any input device they know, without checking the scenario.

That can lose marks if the device is not suitable for the system described.

⚠️ Common Mistake: giving keyboard or mouse for every question. Match the input device to the context.
Figure 8.1
Match the Context
Scenario
↓
What data is needed?
↓
Choose device
9. Summary

Input devices in one screen.

Input devices collect data from the real world and send it into the computer.

They include keyboards, mice, microphones, touchscreens, scanners, cameras, barcode readers and sensors.

💡 Key idea: input devices translate real-world data into data the computer can process.
Figure 9.1
Input Summary
Input
= into computer

Real world
↓
Binary data