GCSE (9-1) Computer Science
Mark Scheme
J277/01: CPU Performance
Question Answer Marks Guidance
1
  • Clock speed
  • Cache size
  • Number of cores
 3
Do not accept: "RAM" or "SSD" (these are not characteristics of the CPU).
2
  • The number of FDE (Fetch-Decode-Execute) cycles run per second. (1)
  • 3.8 billion cycles/instructions per second. (1)
 2
1 mark for definition (cycles per second).
1 mark for the correct number (3.8 billion).
Do not accept: "Speed of the computer".
3
  1. False
  2. False
  3. True
 3
1 mark per correct tick.
4a Computer 1 has more cores (4 vs 2). 1
Must compare the cores. Ignoring the lower clock speed is acceptable for this mark.
4b
  • It allows parallel processing to take place. (1)
  • More instructions/tasks can be processed simultaneously / at the same time. (1)
 2
Key term: "Simultaneously" or "at the same time" is required.
Do not accept: "it processes data faster" (that refers to clock speed).
4c
  • Software may not be designed to use multiple cores. (1)
  • Some tasks cannot be split across cores (sequential processing). (1)
  • Other components (e.g., RAM, Clock Speed) also affect speed. (1)
 3
Max 3 marks.
Must explain why doubling cores doesn't equal double speed.
5 Indicative Content:
  • Cache stores frequently / recently / next-to-be used instructions or data.
  • Cache is faster to access/read from than RAM.
  • More cache means more instructions are available close to the CPU.
  • This reduces the need to fetch data from the slower RAM.
  • Therefore, the CPU spends less time waiting for data, improving efficiency.

Marking Levels:
Level 3 (5-6 marks): Detailed explanation linking storage of frequently used data to reduced RAM access.
Level 2 (3-4 marks): Correctly identifies cache stores frequently used data and is faster than RAM, but explanation of performance impact is less detailed.
Level 1 (1-2 marks): Basic statement (e.g., "More cache makes it faster"). 		6
Use "Level of Response" marking.
OCR 2026