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OCR GCSE Computer Science Exam Questions
1.1 Systems Architecture
1.1 question 2
Complete the table by writing the name of two registers used in the FDE cycle and the purpose of each register.
| Register | Purpose |
|---|---|
4
MARKS
Mark scheme
PC: Stores address of current/next instruction.
MAR: Stores address for data/instruction to be accessed/stored.
Also credit: MDR (stores data/instruction transferred), Accumulator (stores ALU results), CIR/IR (stores current instruction).
MAR: Stores address for data/instruction to be accessed/stored.
Also credit: MDR (stores data/instruction transferred), Accumulator (stores ALU results), CIR/IR (stores current instruction).
Exam guidance
1 mark for correct register + 1 for matching purpose. ‘Pointer’ acceptable for PC/MAR. Do not credit ‘fetches/takes’ as a purpose.
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