Edexcel IGCSEComputer ScienceGeneral Applications4 Marks
Describe the function of the Program Counter (PC) and the Memory Address Register (MAR) in the Fetch-Decode-Execute cycle.
Mark scheme
Marking points from the official mark scheme. The mark or mark type is shown in brackets.
- M1 for Program Counter stores the address of the next instruction to be fetched.
- A1 for PC's content is copied to the MAR during the fetch stage / PC increments after an instruction is fetched.
- M1 for Memory Address Register (MAR) holds the address of the data/instruction to be fetched from memory / written to memory.
- A1 for MAR's content is used to locate the specific memory location.
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