Accumulator (ACC) - The Result Holder
Part of Program Counter & Accumulator — GCSE Computer Science
This key facts covers Accumulator (ACC) - The Result Holder within Program Counter & Accumulator for GCSE Computer Science. Revise Program Counter & Accumulator in Systems Architecture for GCSE Computer Science with 15 exam-style questions and 12 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 4 of 7 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 4 of 7
Practice
15 questions
Recall
12 flashcards
Accumulator (ACC) - The Result Holder
What It Is:
The Accumulator is a register that stores the results of calculations performed by the ALU. It's a temporary workspace for arithmetic and logic operations.
How It Works:
- Before calculation: ACC may hold one of the operands (e.g., in "ADD 5", ACC holds the current value, 5 is added to it)
- During EXECUTE: The ALU performs the operation
- After calculation: The result is stored in the ACC, overwriting the previous value
- Can be used again: The ACC value can be used in the next operation or stored to memory with a STORE instruction
Key Characteristics:
- Holds data values (not addresses or instructions)
- Updated during the EXECUTE stage of the FDE cycle
- Acts as an implicit operand for many ALU instructions
- Faster than storing results to main memory (RAM)
Real-world analogy: Like a calculator's display screen. When you calculate 5 + 3, the screen shows 8. When you then multiply by 2, the screen updates to 16. The ACC works the same way - showing the current result.