A Level Computer Science OCR Practice Exam

The accumulator is a special register within the CPU that is specifically designed to hold data that is currently being processed. This includes intermediate results of arithmetic and logic operations performed by the CPU. The role of the accumulator is crucial as it acts as a temporary storage area for this data, enabling efficient execution of instructions without needing to repeatedly access slower memory components.

In contrast, the program counter is responsible for tracking the address of the next instruction to be executed, while the memory address register holds the address of data in memory that the CPU is accessing. The memory data register, on the other hand, holds the actual data that has been fetched from memory or that is about to be written to memory. Therefore, while these other registers play important roles in the overall function of the CPU and data management, the accumulator is the one dedicated to holding the data currently in active processing.