Oxford Cambridge and RSA
GCSE (9-1) Computer Science
Computer Systems
J277/01
Topic: The Fetch-Execute Cycle
Time allowed: 30 minutes
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INSTRUCTIONS INFORMATION
Turn over
Section A: Stages & Sequence
1
The CPU continuously repeats a cycle to process data.

(a) Identify the three stages of this cycle in the correct order.
[3]
(b) State the name of the component where instructions are fetched from during this cycle.
[1]
2
Tick one box in each row to show whether each statement about the Fetch-Execute cycle is True or False.
[4]
Statement True False
The Program Counter (PC) stores the instruction currently being executed.
The cycle repeats continuously while the computer is turned on.
During the decode stage, the instruction is interpreted by the Control Unit.
The MAR stores the address of the instruction to be fetched.
Turn over
Section B: Registers in the Cycle
3
Registers play a vital role in moving data during the cycle.
Complete the table by describing the specific purpose of each register during the fetch-execute cycle.
[4]
Register Purpose in the Fetch-Execute Cycle
Program Counter (PC)
Memory Address Register (MAR)
Memory Data Register (MDR)
Accumulator (ACC)
4
A student states: "The Program Counter (PC) counts how many programs have been run."
Explain why the student is incorrect.
[2]
Section C: Extended Process
5
Describe the events that take place during the Fetch and Decode stages of the cycle.
In your answer, you must refer to how the registers are used to transfer data.
[6]
END OF QUESTION PAPER