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Memory Buffer Register

The memory buffer register is located in the centre processor.
It can store the data which is being transferred to and from the immediate access store.
It just works like buffer to let the centre processor and memory act independently without being affected by minor differences in operation. In other words, the data item can store in there for prepare either process in the centre processor or store directly in the memory unit.

Memory Address Register

The Memory Address Register is half of a minimal interface between and computer storage.
It holds the next address of memory location where the first instruction is being executed.
Explain in simplify, when the first instruction is executed and it hold the next address of memory location. After the first instruction has been completed the computer CPU will use the address bus to communicate which memory address it wants to access, then and the memory controller reads the address and then puts the data stored in that memory address back onto the address bus for the CPU to use.

Instruction Register

Instruction register is a part of CPU’s control unit which stores the instruction currently being executed. In a simple processor it loads every instruction to be executed and hold it while is decoded, prepared and ultimately executed.

Instruction Buffer Register

The instruction buffer register is employed to hold temporarily the right hand instruction from a word in memory.

Program Counter

The program counter, or shorter PC (also called the instruction pointer, part of the instruction sequencer in some computers) is a register in a computer processor which indicates where the computer is in its instruction sequence. Depending on the details of the particular machine, it holds either the address of the instruction being executed, or the address of the next instruction to be executed. The program counter is automatically incremented for each instruction cycle so that instructions are normally retrieved sequentially from memory. Certain instructions, such as branches and subroutine calls and returns, interrupt the sequence by placing a new value in the program counter.

Accumulator

In a computer's central processing unit (CPU), an accumulator is a register in which intermediate arithmetic and logic results are stored. Without a register like an accumulator, it would be necessary to write the result of each calculation (addition, multiplication, shift, etc.) to main memory, perhaps only to be read right back again for use in the next operation. Access to main memory is slower than access to a register like the accumulator because the technology used for the large main memory is slower (but cheaper) than that used for a register.



Multiplier Quotient

The multiplier-quotient unit is similar to factor storage units and, in addition, it may be used to store the multiplier factor when multiplying or to develop the quotient when dividing.