(a) What is a register? (b) List two types of register. (c) State three functions of registers. (d) Outline three differences between a register and main me...

Answer Details

(a) What is a register?

A register is a small, very high-speed temporary storage location built inside the Central Processing Unit (CPU). It holds a single piece of data, an instruction or an address that the processor is currently working on, so that it can be accessed almost instantly during processing.

(b) Two types of register:

• Accumulator (ACC)
• Program Counter (PC)

Other acceptable examples: Memory Address Register (MAR), Memory Data/Buffer Register (MDR/MBR), Instruction Register (IR), Index Register.

(c) Three functions of registers:

1. They temporarily hold data and instructions that are being processed by the CPU.
2. They store the memory address of the next instruction or of the data to be fetched (for example the Program Counter and Memory Address Register).
3. They hold the intermediate and final results of arithmetic and logic operations (for example the Accumulator).

(d) Three differences between a register and main memory:

(Any three of the above differences are acceptable.)