A CPU (Central Processing Unit) is the most important component of a computer system. It is the electronic circuitry that executes the instructions of a computer program by performing the basic arithmetic, logical, control and input/output operations².

A CPU consists of three major units:

• Memory or Storage Unit: This unit stores data, instructions, programs, and intermediate results. It also communicates with the input and output devices and other components of the computer system¹.

• Control Unit: This unit controls the flow of data within the CPU and between the CPU and other devices. It interprets the instructions of the program and coordinates the activities of the ALU and the memory unit¹.

• ALU (Arithmetic Logic Unit): This unit performs arithmetic and logic operations on data. It can perform operations such as addition, subtraction, multiplication, division, comparison, etc¹.

The following diagram shows a simplified representation of the CPU architecture:

Source: [2]

The diagram shows how the CPU communicates with other components of the computer system through buses. A bus is a set of wires that carries data, address, or control signals. There are three types of buses:

• Data Bus: This bus transfers data between the CPU and the memory or input/output devices.

• Address Bus: This bus carries the address of the memory location or input/output device that the CPU wants to access.

• Control Bus: This bus carries control signals that indicate the type of operation that the CPU wants to perform.

The diagram also shows how the CPU uses registers to store data temporarily. A register is a small and fast memory unit inside the CPU that can hold a single value. There are different types of registers, such as:

• Accumulator: This register stores the result of an arithmetic or logic operation performed by the ALU.

• Program Counter: This register stores the address of the next instruction to be executed by the CPU.

• Instruction Register: This register stores the instruction that is currently being executed by the CPU.

• General Purpose Registers: These registers can store any data or address that is needed by the CPU.