Lesson Notes By Weeks and Term v4 - SHS 1

Lesson Video

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Performance objectives

• Identify the four major functions of the CPU.
• Explain the roles of the Arithmetic and Logic Unit (ALU), Control Unit (CU), and registers.
• Understand basic data manipulation using functions.

Lesson summary

Welcome, learners. In our last lesson, we looked at the basic components of a computer system. Today, we are going to zoom in on the most important component: the "brain" of the computer, the Central Processing Unit (CPU). Think about your own brain. It helps you think, calculate, make decisions, and control your body. The CPU does something very similar for a computer. Whether you are sending a WhatsApp message, playing a game, calculating a MoMo transaction, or even just typing your name, the CPU is at the heart of it all, processing every single instruction. Understanding how this 'brain' works is fundamental to understanding how computers manipulate data to perform amazing tasks.

Lesson notes

A. What is the Central Processing Unit (CPU)?

The Central Processing Unit (CPU), also called the microprocessor, is the electronic circuitry that executes instructions comprising a computer program. It is often referred to as the brain or heart of the computer because it performs most of the processing inside the computer. It is responsible for taking raw data and turning it into useful information. Location: The CPU is a small chip found on the motherboard of the computer. Function: Its primary job is to perform calculations, make logical comparisons, and move data around the computer system. B. The Major Functions of the CPU: The Machine Cycle

For the CPU to process any data or instruction, it follows a four-step cycle. This is called the Machine Cycle or the Instruction Cycle. Think of it as a chef following a recipe, one step at a time. FETCH: The CPU retrieves (fetches) an instruction from the main memory (RAM). *Analogy:* A teacher picking up the next question from a textbook to ask the class. DECODE: The CPU translates the fetched instruction into a series of commands that it can understand. *Analogy:* The teacher reads the question and understands what it is asking. Does it need a definition? A calculation? A comparison? EXECUTE: The CPU carries out the commands. This is where the actual work is done. *Analogy:* The teacher asks the question, and a student provides the answer. The action is performed. STORE: The CPU saves the result of the executed instruction. This result can be stored back in a register or in the main memory (RAM) for later use. *Analogy:* The teacher writes down the student's correct answer (or marks) in a record book.

This cycle—Fetch, Decode, Execute, Store—happens millions or even billions of times per second! C. The Three Main Parts of the CPU

Evaluation guide

• Discuss at least four major functions and the parts of the CPU
• Arithmetic and
• Logic Unit (ALU), Control Unit (CU) and registers
• Using Talk for Learning approaches (TfL) or snowballing :