GCSE (9-1) Computer Science
Mark Scheme
J277/01: Components & Architecture
Question Answer Marks Guidance
1a
  1. To process instructions / data.
  2. To perform the Fetch-Execute cycle.
 1
Reject: "Brain of the computer".
1b Fetch-Execute Cycle / F-E Cycle / FDE Cycle 1
2
  1. Central Processing Unit
  2. Instructions
  3. Memory / Main Memory / RAM
  4. Control
 4
1 mark per correct gap.
Ignore: "Data" if used instead of Instructions.
Accept: RAM/Registers for "Memory".
3
  1. True
  2. False (Measured in Hz/GHz)
  3. False
 3
1 mark per correct row.
Note: Storage is not part of the CPU.
4
  1. CU: Sends signals to direct operations...
  2. Cache: High speed memory...
  3. ALU: Performs mathematical...
  4. Register: A small piece of memory...
 4
1 mark per correct line.
Any 2 lines from 1 component = 0 marks for that component.
5a
  1. Program Counter (PC)
  2. Memory Address Register (MAR)
  3. Memory Data Register (MDR)
  4. Accumulator (ACC)
 1
Accept: Correct abbreviations (e.g., CIR, IR).
5b
  1. PC: Stores address of next instruction.
  2. MAR: Stores address of data/instruction to be fetched.
  3. MDR: Stores data/instruction fetched from memory.
  4. ACC: Stores result of calculations.
 1
Must match the register named in 5a.
Constraint: Action verbs (fetches/takes) are not sufficient; must imply storage.
6a
  1. The CPU can perform 3.8 billion cycles/instructions per second.
  2. The number of FDE cycles run per second.
 2
1 mark for "cycles per second".
1 mark for correct number (3.8 billion).
Reject: "Speed of CPU".
6b
  1. Software may not be designed to use multiple cores.
  2. Some tasks cannot be split across cores / depend on previous tasks.
  3. The other computer may have a faster clock speed / more RAM / more cache.
 3
Max 3 marks.
Must imply that cores work simultaneously or in parallel.
OCR 2026