Identify the function of the control unit in the fetch-decode-execute cycle.
Mark scheme
- A Decodes instructions (1)
- The only correct answer is A. The correct answer is Decodes instructions.
- B is not correct because the arithmetic logic unit performs arithmetic operations
- C is not correct because main memory stores data and instructions
- D is not correct because registers temporarily store data being processed
Example answers and how they were marked
Full marks1/1
A Decodes instructions
Why: Correct option: the control unit decodes instructions during the fetch-decode-execute cycle (1).
No marks0/1
C Stores data and instructions
Why: Main memory stores data and instructions, not the control unit; this is a common distractor, so no mark.
No marks0/1
B Performs arithmetic operations
Why: Arithmetic operations are performed by the ALU, not the control unit; a common confusion between CPU components, so no mark.