A computer system consists of hardware and software working together to process data.

• Hardware is the name of the physical components that make up the computer system.
• Software is the name for the programs that provide instructions for the computer, telling it what to do.

A computer system receives information as an electrical input, processes and stores that information, and then outputs the results.

The Central Processing Unit (CPU)

The CPU is made up of billions of transistors, which are like very small on/off switches. The arrangement (disposizione) of transistors creates logic circuits that process data, carry out instructions and control the components of the computer.

The processor continually:

1. Fetches (recupera) instructions from memory;
2. Decodes these instructions;
3. Executes them.

This is called the fetch-execute cycle.

Common CPU Components and Their Function

Arithmetic Logic Unit (ALU)

Responsible for:

• Arithmetic operations: add, subtract, multiply, divide;
• Logical operations: AND, OR, NOT;
• Binary shift operations.

Control Unit (CU)