GCSE-readyComputers all around us: embedded systems and sensors
Most computers are not laptops or phones. They are hidden inside washing machines, cars and traffic lights. These are embedded systems.
Embedded systems
Examples: a washing machine, a microwave, a car's anti-lock brakes, a fitness tracker, a smart thermostat.
A general-purpose computer, such as a laptop, can run many different programs. An embedded system usually runs one fixed program, often stored in ROM or flash memory.
Sensors and actuators
| Part | What it does | Examples |
|---|---|---|
| Sensor (input) | measures something in the real world | temperature, light, motion, pressure, sound |
| Processor | decides what to do using its program | a small chip called a microcontroller |
| Actuator (output) | makes something happen in the real world | a motor, a heater, a buzzer, a light |
Example: an automatic night light
The program checks: IF light level < limit THEN turn the lamp on ELSE turn it off.
This check repeats forever, many times a second.
In school you may program a small board such as the BBC micro:bit, which has buttons, an LED display and built-in sensors, to do jobs like this.
A greenhouse system keeps plants warm. Identify the sensor, the actuator and the rule.
- Sensor: a temperature sensor measures the air.
- Actuator: a heater warms the air.
- Rule: IF temperature < target THEN heater on ELSE heater off, repeated all the time.
Answer: Temperature sensor, heater, and a repeated IF check against a target temperature.
An embedded system is a computer built into a device to do one dedicated job. Sensors measure the real world (input), a microcontroller runs the program (process), and actuators such as motors and heaters make things happen (output).
- AND
- A Boolean operator that gives True (1) only when both inputs are True.
- NOT
- A Boolean operator that flips its input: True becomes False and False becomes True.
- Input
- Data put into a computer, for example from a keyboard, mouse, microphone or sensor.
- Program
- A set of instructions written in a programming language that a computer can run.
- Output
- Information sent out from a computer, for example to a screen, speaker or printer.
- Bit
- A binary digit: a single 0 or 1. The smallest unit of data.
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2 more questions
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Which of these is a computer built into a device to do one job?
- A gaming PC
- The controller in a microwave oven
- A laptop
- A smartphone running many apps
Show the answer
Answer: The controller in a microwave oven
A microwave controller does one job.
A greenhouse waters plants when the soil is dry. Which sensor is needed?
- Moisture sensor
- Light sensor
- Sound sensor
- Distance sensor
Show the answer
Answer: Moisture sensor
A moisture sensor measures soil water.
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Last updated 2 October 2026. Spotted a mistake? Tell us and we will fix it.