Describe the functioning of CPU.

CPU is the brain of a computer system and it executes the programs in following manner :

1. When a program reaches into memory, the control unit (CU) of CPU reads the program instructions one by one.
2. The CU then determines the type of instruction i.e., whether it is an arithmetic (calculations) or logical (comparisons) or I/O (reading or writing) type of instruction.
3. For arithmetic or logical type of instructions, CU directs the ALU (Arithmetic and logic unit) to carry out the instructions.
4. For input type of instruction, CU directs the Input unit to carry out the instruction and for Output type of instruction, it directs the output unit to carry out the instruction.