This exam tips covers Exam Tips - PC and Accumulator within Program Counter & Accumulator for GCSE Computer Science. Revise Program Counter & Accumulator in 3.4 Computer Systems for GCSE Computer Science with 15 exam-style questions and 12 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 7 of 8 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
Exam Tips - PC and Accumulator
Common exam questions and how to answer them:
- "When does the PC change?" → During the FETCH stage, it increments by 1
- "When does the ACC change?" → During the EXECUTE stage, when ALU stores a result
- "What does the PC hold?" → The address (not the instruction itself!) of the NEXT instruction
- "What does the ACC hold?" → The result of the most recent ALU operation
Common mistakes to avoid:
- Saying PC holds "the current instruction" - it holds the ADDRESS of the NEXT instruction
- Saying PC increments during EXECUTE - it increments during FETCH
- Confusing ACC with other registers (MAR/MDR) - ACC is specifically for ALU results
- Forgetting that branch/jump instructions change the PC to non-sequential addresses
Practice questions for Program Counter & Accumulator
What does the Program Counter (PC) store?
Explain what happens to the Program Counter during the fetch stage of the FDE cycle.
Quick recall flashcards
What does PC stand for?
Program Counter
What does ACC stand for?
Accumulator