Registers

Stores the intermediate results of calculations or other processes.

The calculation ‘5 + 2 – 4’ would be partially complete at ‘5 + 2’.

At this point, ‘7’, the intermediate result, would be stored in the accumulator 

Stores the instruction or process to be carried out on the data.

Using the calculation ‘5 + 2 – 4’,

The memory instruction register will, at some point, contain a reference to addition and subtraction at various points. 

Stores the memory location that is to be accessed next.

If an instruction is about to be accessed,this register will contain the same memory location as the program counter;

if data is about to be accessed, it will be different. 

Stores data to be processed.

If the processor is carrying out the calculation ‘5 + 2 – 4’, at various points, the numbers ‘5’ and ‘2’ will be stored in the memory data register.

Stores the memory location of the next instruction to be accessed.