1. Data Representation
IGCSE Computer Science (0478)
  • Data Representation
    • Introduction
    • Why computers use binary (how binary represents data)
    • Number system
      • Introduction
      • Number Conversions
      • Addition of Binary Numbers
      • Logical binary shifts (positive 8-bit integers)
      • Two’s Complement (Signed: Positive and Negative Numbers)
      • Use of the Hexadecimal System
    • Text, Sound and Image
      • Text, Sound and Images
      • File Types
    • Data storage and File compression
      • Measurement of the Size of Computer Memories
      • Lossless and Lossy File Compression
  1. Data Representation

Why computers use binary (how binary represents data)

Computers are built from tiny switches (transistors).
Each switch has two states:
ON → 1
OFF → 0
A series of 1s and 0s is called binary. Each 1 or 0 is a bit.
Everything on a computer (text, images, sound, games) is stored as bits.
Real-life example: A bulb is either ON or OFF. That is binary.
Class task (quick): Name two devices at home that are ON/OFF (fan switch, TV remote power).

Importance#

#ReasonExplanation
1Only two statesComputers use ON (1) or OFF (0)
2Easy to tell apart1 and 0 are very different and clear
3Simple to useUsing two choices is easier than many
4Very reliableLess chance of mistakes happening
5Fast calculationsComputers can quickly work with 1s and 0s
6Used everywhereAll computers use binary system
7Helps find mistakesMakes it easier to spot errors
Modified at 2025-08-11 06:02:30
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Introduction
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Number system
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