Register (CPU)

A CPU  contains a number of registers to stores data temporarily during the execution of a program.The number of registers differs from processor to processor.some processors contain more registers,some less.Register are classified as follows:

ACCUMULATOR:The accumulator is a register which holds one of the operands prior to the execution of an instruction,and receives the results of most of the arithmetic and logical operations.So an accumulator is the most frequently used register.Some CPUs have a single accumulators;some have several accumulators.

General Purpose Registers:These registers store data and intermediate results during the execution of a program.They are accessible to users through instructions if the users are working in assembly language.

Special Purpose Registers: A CPU contains a number of special purpose registers for different purposes.These are:

(i)Program Counter(PC)

(ii)Stack Pointer(SP)

(iii)Status Register 

(iv)Instruction Register(IR)

(v)Index Register 

(vi)Memory Address Register(MAR)

(vii)Memory Buffer Register (MBR) or Data Register (DR)

All CPUs do not contain all of these special registers.A powerful CPU contains most of them.The brief description of these registers is given below:

Program counter

stack pointer 

status Register