Lesson Notes By Weeks and Term v4 - SHS 2
DATA STORAGE AND MANIPULATION
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DATA STORAGE AND MANIPULATION
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Subject: Computing
Class: SHS 2
Term: 1st Term
Week: 5
Grade code: 2.1.1.LI.3
Strand code: 1
Sub-strand code: 1
Content standard code: 2.1.1.CS.1
Indicator code: 2.1.1.LI.3
Theme: COMPUTER ARCHITECTURE & ORGANISATION
Subtheme: DATA STORAGE AND MANIPULATION
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This lesson explores the fundamental arithmetic operations that form the basis of all calculations performed by a computer. While we see complex results like video games, financial reports, or social media feeds, at the core, the computer's processor is performing millions of simple mathematical operations per second. Understanding how a computer performs addition, subtraction, and multiplication using binary numbers (0s and 1s) is crucial to understanding how data is manipulated. In our daily lives in Ghana, from a mobile money agent calculating a transaction fee to a store's computer system tracking inventory, these basic operations are constantly at work.
A. The Arithmetic Logic Unit (ALU)
Before we dive into the operations, we need to know *where* they happen. Inside the computer's CPU (the "brain"), there is a special component called the Arithmetic Logic Unit (ALU). Definition: The ALU is a digital circuit within the CPU responsible for performing all arithmetic operations (like addition, subtraction) and logic operations (like AND, OR, NOT). Function: Think of the ALU as the calculator of the computer. Whenever you ask the computer to do any math, the data (in binary form) is sent to the ALU, which performs the calculation and sends back the result. It is the mathematical workhorse of the entire system. B. Binary Number System (A Quick Recap)
Computers don't understand our decimal numbers (0-9). They only understand two states: ON (1) and OFF (0). This is the binary system. All data, including numbers, text, and images, is stored and manipulated as a sequence of 0s and 1s, called bits. A group of 8 bits is called a byte. Example: The decimal number `13` is `1101` in binary. In an 8-bit system (a byte), we write it as `00001101`. C. The 3 Major Arithmetic Operations in Computing Binary Addition
This is the most fundamental operation. The ALU performs addition using rules similar to decimal addition, but much simpler. Rules of Binary Addition: `0 + 0 = 0` `0 + 1 = 1` `1 + 0 = 1` `1 + 1 = 0`, with a carry-over of `1` to the next column. `1 + 1 + 1 = 1`, with a carry-over of `1` to the next column.