The Central Processing Unit (CPU) consists of

The correct answer is ALU, Control unit, Registers, and Internal bus.

Key Points

There are three basic units of a computer system:

1. Input Unit: Keyboard, Mouse, Scanner, Light pen, Trackball etc.
2. Central Processing Unit
3. Output Unit: Monitor and Printer

Central Processing Unit (CPU): It is the most important unit, where all the processing jobs take place. CPU is the control centre of the computer and hence it is said to be the brain of the computer. CPU has three main components:

1. Arithmetic Logic Unit (ALU): It performs all the arithmetic operations like addition (+), multiplication (*), subtraction (-), division (/) on the numerical data directed by the control unit. All the logical operations, like less than (<), greater than (>), equal to (=), not equal to (≠) etc. are also carried out by ALU.
2. Control Unit (CU): It controls and coordinates all the operations taking place in the system. It controls the flow of data and information from one unit to the other.
3. Registers/Memory Unit (MU): To execute a program, data and instructions need to be stored temporarily. This storage is done in the MU. The data and instructions are retrieved from MU by Control Unit for supplying to ALU as when required by the program.
4. Internal bus: To transfer the data