Main Memory: Main memory work as a paper.Which corresponds in the manual calculation.It’s work is to store instruction and data.
CPU:Central Processing Unit.It acts a brain of the computer.
PCU:Program Control Unit is a part of CPU.It fetch instructions from memory and interpret them.It also known as Instruction unit.
ALU:It’s also a part of CPU .Known as arithmetic logic unit.It’s work is to CPU’s data execution or data processing and carries out the instruction.
