This part of the computer that executes program instructions is known as the
processor or Central Processing Unit (CPU). In a microcomputer, the CPU is
based on a single electronic component, the microprocessor chip, within the
system unit or system cabinet. The system unit also includes circuit boards,
memory chips, ports and other components. Amicrocomputer’ s system cabinet
will also house disk drives, hard disks, etc., but these are considered separate
from the CPU.
The CPU has two parts —The Control Unit (CU) and the Arithmetic Logic Unit
(ALU). In a microcomputer , both are on a single microprocessor chip.
Control Unit (CU)
The control unit tells the rest of the computer system how to carry out a program’ s
instructions. It directs the movement of electronic signals between memory -which temporarily holds data, instructions and processes information - and the
ALU. It also directs these control signals between the CPU and input/output
Arithmetic - Logic Unit (ALU)
Arithmetic Logic Unit, usually called the ALU, performs two types of operations
- arithmetical and logical.