Practise Embedded systems. 11 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
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Define the term 'embedded system'.
A computer system inside a larger device that performs a dedicated function.
Give one input device and one output device that the thermostat uses.
Input: temperature sensor. Output: a relay that switches the boiler (or a display).
Give one reason why the embedded system in a microwave oven has only a simple user interface.
It only has a few tasks, so a few buttons are enough and cost is kept down.
Sample questions
Written for this site in the style of Edexcel exam questions. They are not taken from real past papers.
Question 1Easy3 marks
(a) Define the term 'embedded system'.[1]
(b) Give two examples of devices that contain an embedded system.[2]
Show the answer and mark scheme
(a)Answer: A computer system inside a larger device that performs a dedicated function.
a computer system built into a larger device to carry out a specific (dedicated) task / a limited set of tasks
(b)Answer: Any two from: washing machine, microwave, dishwasher, engine management system, thermostat, traffic lights…
washing machine
microwave oven
dishwasher
car engine management system
anti-lock braking system
central heating controller / thermostat
traffic lights
digital camera
pacemaker
Question 2Medium4 marks
Describe two differences between an embedded system and a general-purpose computer such as a laptop.[4]
Show the answer and mark scheme
Answer: Dedicated task vs many programs; fixed firmware vs user-installed software (also: simple interface, low power).
an embedded system carries out one dedicated task / a small set of tasks
whereas a general-purpose computer can run many different programs chosen by the user
the program in an embedded system is usually fixed (firmware in ROM or flash memory) and rarely changed
whereas users can install, update and remove software on a general-purpose computer
an embedded system usually has a very simple user interface, e.g. a few buttons and a small display
whereas a general-purpose computer has a full user interface, e.g. keyboard, mouse and screen
an embedded system is usually smaller, cheaper and uses less power
Question 3Hard4 marks
A car's anti-lock braking system (ABS) is an embedded system. It uses sensors to detect when a wheel is about to lock (stop turning) and releases the brake on that wheel for a fraction of a second.
Explain why the ABS is a separate embedded system rather than one of the programs run by the car's touch-screen entertainment computer.[4]
Show the answer and mark scheme
Answer: Braking must react instantly and reliably; sharing a processor could delay it, and a fault in the entertainment software could disable the brakes.
the ABS must respond in real time, within milliseconds of the sensor data changing
if it shared a processor with other programs, it could be delayed or slowed down
a crash or bug in the entertainment software could stop the ABS from working
so the car would be unsafe: the brakes might not release, causing a skid
a dedicated system is simpler, so it can be tested more thoroughly and is more reliable