Central Processing Unit

Class: SSS Two

Definition of the CPU

The Central Processing Unit (CPU), also known as the microchip, microprocessor, or simply processor, is the electronic circuitry inside a computer that executes instructions from computer programs. Think of it as the brain or heart of the computer. Its main job is to execute instructions from computer programs, which involves performing mathematical calculations and logical operations using binary numbers (the 0s and 1s that computers understand).

Today, almost all CPUs are microprocessors, meaning they are very small chips built on a single integrated circuit (IC). Many modern computers use a multi-core processor, which is a single chip containing two or more CPUs called "cores." These multi-core processors allow computers to handle many tasks at once, making them much faster and more efficient.

Brief History of the CPU

The invention of the Microprocessor marked the beginning of the fourth generation of computers. This was a huge leap forward, making computers much smaller, more powerful, and eventually, affordable for everyday use.

Ted Hoff produced the first microprocessor, the Intel 4004, in 1971 for Intel. This groundbreaking invention paved the way for the personal computers we use today.

Picture of the CPU

This image shows a typical CPU chip, often found on the motherboard of a computer.

Main Components of the Central Processing Unit

The Central Processing Unit (CPU) consists of two main parts:
1. Control Unit (CU)
2. Arithmetic Logic Unit (ALU)

The Control Unit (CU)

The Control Unit (CU) acts like an orchestra leader, using electrical signals to direct the entire computer system to carry out stored program instructions. Just like a conductor doesn't play an instrument but tells others when to play, the control unit doesn't execute program instructions itself. Instead, it directs other parts of the system, like the ALU and memory, to do so. It constantly communicates with both the Arithmetic Logic Unit and memory.

Functions of the Control Unit:

• It activates the appropriate circuits necessary for input and output devices to function.
• It ensures the computer system operates smoothly by coordinating all its parts automatically.
• It directs the system to execute instructions in the correct order.
• It helps in communication between the memory and the Arithmetic Logic Unit.
• It aids in loading data and instructions from secondary memory (like a hard drive) to the main memory (RAM) as required for processing.

The Arithmetic Logic Unit (ALU)

The Arithmetic Logic Unit (ALU) is the part of the CPU that performs all arithmetic operations and logical operations. It's where the actual "thinking" and calculating happen.

Functions of the ALU:

• The ALU executes arithmetic and logical operations.
  • Arithmetic operations include mathematical calculations like addition, subtraction, multiplication, and division.
  • Logical operations compare numbers, letters, and special characters. For example, it checks if one value is equal to another, greater than another, or less than another.
• It compares operations to test for conditions such as:
  • Is A equal to B?
  • Is A greater than B?
  • Is A less than B?

Central Processing Flow Diagram

This diagram illustrates how data flows within the CPU and interacts with memory and input/output devices.