Computer systems and networks · GCSE Computer Science

Input and output devices

GCSE Computer Science input and output devices: sensors, keyboards, touchscreens, monitors, actuators, printers — data flow into and out of the CPU.

UNDERSTAND→RETRIEVE→REMEMBER
THE MEMORY HOOK
Input: data into the computer. Output: information out to the human or machine. Sensor in, actuator out — same I/O idea for control systems.

The important bits

What you need to know

  1. 1

    Input devices send data to the computer: keyboard, mouse, microphone, scanner, webcam, barcode reader, sensors.

  2. 2

    Output devices present results: monitor, speaker, printer, LED display, projector, actuator (motor, relay, buzzer).

  3. 3

    Sensors are input measuring the physical world: temperature, light, pressure, motion, moisture — often analogue values digitised.

  4. 4

    Actuators are output that move or change the physical world: motors, heaters, solenoids, speakers as output to air.

  5. 5

    Touchscreens are input (touch position) and sometimes output (display) — dual-role device.

  6. 6

    Storage is neither pure input nor output — data is read (input to CPU) and written (output from CPU) but retains state.

  7. 7

    USB and wireless connect many I/O devices; the CPU processes data via drivers that translate device signals.

  8. 8

    Choose device by scenario: RFID gate input, thermal printer output receipt, GPS sensor input location for navigation output on screen.

Quotations worth analysing

Short evidence. Real method.

“Input sends data to the computer”
GCSE I/O definition

Direction matters. A monitor is output even though it “shows” data — data flows out to the user. Students swap when tired.

“Sensor measures, actuator moves”
Control systems GCSE

Temperature sensor input, heater actuator output. Both are I/O but different ends of the physical interface.

“Touchscreen: input and output combined”
Dual-purpose device example

Exam may ask classify — accept both roles. Display part is output; touch coordinates are input.

Go deeper

Common input devices in scenarios

Checkout: barcode scanner input, chip reader input. Factory: pressure sensor input, limit switch input. Home: PIR motion input, door magnetic contact. Biometric: fingerprint scanner input. Each converts physical state to digital data the CPU reads via driver. Sampling rate matters for microphones — CD quality 44.1 kHz. OCR scanner input text image as characters. Exam “suggest an input device”: tie to data needed — moisture for plants, not keyboard.

Go deeper

Output for humans and machines

Monitor pixels output for eyes. Inkjet/laser printer output hard copy. Plotter output large diagrams. Braille embosser output tactile. Actuator: stepper motor output rotation for CNC; relay output switches high-voltage device. Buzzer output sound alert. Haptic feedback output vibration on phone. 3D printer output physical object layer by layer — classified output. LED status lamp output one bit of state. Multiple outputs often together: screen message plus beep on error.

Go deeper

Drivers and interfaces

CPU does not natively speak every device protocol. Driver software translates OS calls to device commands. USB HID standard for keyboard/mouse. Bluetooth pairing for wireless headphones output. ADC converts analogue sensor voltage to digital for input. GCSE may ask why driver needed — device-specific translation. Hot-plug USB input device enumerated on connect. I/O ports memory-mapped on some embedded boards — beyond GCSE detail but explains “how data gets in”.

WORKED EXAMPLE

See the idea in action

Smart heating system. Inputs: temperature sensor (room temp), thermostat buttons (desired temp), timer schedule from app (network input). Outputs: radiator valve actuator (heat on/off), LCD screen (current temp), LED (heating active), optional email alert output. Processing: CPU compares sensor input to setpoint, decides actuator state. Not storage as primary role — though logs may write to disk.

Exam technique

Turn knowledge into marks

Classify by data direction relative to CPU. “Suggest input” and “suggest output” must match the scenario’s data — justify in one phrase.

Common mistakes

Do not give these marks away

  1. 01

    Calling a monitor an input device because the user looks at it.

  2. 02

    Classifying a hard drive as only input or only output — it is storage with read/write I/O.

  3. 03

    Forgetting actuators as output in control system questions.

QUICK RETRIEVAL

Which is an output device?

ABarcode scanner

BMicrophone

CLaser printer

DKeyboard

Show the answer

Laser printer. Printer sends data out as paper. Scanner, microphone and keyboard send data into the computer.

Quick questions

If this is the bit you searched

Is a touchscreen input or output?

Both: display is output, touch detection is input. State both if the question allows dual classification.

What is an actuator?

An output device that causes physical action — motor, relay, buzzer, valve — used in control systems.

What is the difference between sensor and input device?

Sensors are a type of input measuring physical properties. Keyboards input human-entered symbols. Both send data to the CPU.

Why are drivers needed?

Software that lets the OS communicate with specific hardware, translating generic commands to device signals.