An engine control unit (ECU) in a car is an embedded system.
Explain one benefit of using an embedded system for the engine control unit instead of a general purpose computer.
Mark scheme
Award up to two marks for a linked explanation such as:
- (The ECU) is more reliable/less likely to crash (1) because it only runs the one program/has a single purpose (1)
- (The ECU) cannot be affected by other software/viruses (1) because it cannot run other software/it can only run the program it was made for (1)
- (The ECU) is cheaper (1) because it has limited processing resources/less memory/simple components (1)
- (The ECU) uses less power (1) because it has limited processing resources/a simpler processor (1)
- (The ECU) is smaller (1) because it has fewer components/less memory than a general purpose computer (1)
For both marks, the expansion must follow/associate with the statement.
A suitable benefit stated on its own earns one mark.
Do not accept a description or a location given as the reason, e.g. 'because it is part of the car', 'because it is inside the engine', 'because it is embedded'.
Do not accept a description of an embedded system on its own as the benefit, e.g. 'it does one specific job' or 'it is part of the car'.
Do not accept 'it is faster'/'it has a more powerful processor' as embedded systems have limited processing resources.
Example answers and how they were marked
It is more reliable than a general purpose computer (1) because it only runs the one program so it will not crash and stop the engine working (1).
Why: Benefit stated (1) with a linked reason (1); the reason shows why only running one program makes it reliable.
It is more reliable (1) because it is part of the car's engine (1).
Why: Only the benefit earns a mark (1); being part of the car is a location, not a linked reason why it is reliable.
It is faster than a general purpose computer (0) because it is embedded in the engine (0).
Why: Misconception that an embedded system is faster; embedded systems have limited processing resources, so neither point nor reason is creditworthy.