1.2.20

ASCII & Unicode

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American Standard Code for Information Interchange

The American Standard Code for Information Interchange (ASCII) character set is the most common character set.

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ASCII

  • Each character in ASCII is represented by a seven-bit binary code.
    • That means there is a maximum of 128 characters.
  • ASCII includes all commonly used letters and symbols in the English language.
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7-bit letters?

  • Each letter is represented by seven bits.
  • This is useful because when used in an 8-bit system, the extra bit can be used as a check digit.
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Limitations of ASCII

  • 128 characters is perfectly fine for the English language. But it does not leave space for characters from other languages.
  • An extended ASCII set was released which used all eight bits, but it was still not enough.
  • This led to the release of Unicode.

Unicode

Unicode is a character set which was released because of the need to standardise character sets internationally.

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Unicode

  • Unicode aims to represent every possible character in the world.
  • The most common form of Unicode is UTF-8 and uses between eight and 32 bit binary codes to represent each character.
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Compatability with ASCII

  • The first 256 characters in Unicode are identical to extended ASCII, which makes it backwards compatible with documents encoded using older character sets.
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Types of characters

  • Unicode represents characters from all major alphabets of the world.
  • Unicode is also used to represent emojis!

Jump to other topics

1Computer Systems

1.1Systems Architecture

1.1.1Architecture Introduction

1.1.2Von Neumann Architecture

1.1.3Fetch-Execute Cycle

1.1.4Factors Affecting CPU Performance

1.1.5Elements of Computer Systems

1.1.6Exam-Style Questions - Von Neumann Architecture

1.2Memory & Storage

1.2.1Types of Memory

1.2.2Flash Memory

1.2.3Virtual Memory

1.2.4Exam-Style Questions - Primary Memory

1.2.5Capacity

1.2.6Solid State Storage

1.2.7Magnetic Storage

1.2.8Examples of Magnetic Storage

1.2.9Optical Storage & its Properties

1.2.10Examples of Optical Storage

1.2.11End of Topic Test - Computer Systems

1.2.12Grade 9 - Storage

1.2.13Exam-Style Questions - Storage

1.2.14Units of Information

1.2.15Number Bases

1.2.16Converting Number Bases

1.2.17Hexadecimal

1.2.18Binary Arithmetic

1.2.19Representing Text

1.2.20ASCII & Unicode

1.2.21Representing Images

1.2.22Representing Sound

1.2.23Data Compression

1.2.24End of Topic Test - Representation

1.2.25Exam-Style Questions -Data Conversions

1.3Computer Networks, Connections & Protocols

1.3.1Benefit of Networks

1.3.2Network Performance

1.3.3Networks: How Do Packets Get Routed?

1.3.4Types of Networks

1.3.5Client-Server Model

1.3.6Pros & Cons of Client-Server Model

1.3.7Peer-to-Peer Model

1.3.8Pros & Cons of Peer-to-Peer Model

1.3.9Network Hardware

1.3.10What is the Internet?

1.3.11URLs

1.3.12DNS & Web Hosting

1.3.13The Cloud

1.3.14Pros & Cons of the Cloud

1.3.15Exam-Style Questions - Networking Models

1.3.16Topology

1.3.17WiFi

1.3.18WiFi Encryption

1.3.19IP Addresses

1.3.20MAC Addresses

1.3.21Network Protocols

1.3.22Application Protocols

1.3.23Layers

1.3.24Advantages of Layering

1.3.25Exam-Style Questions - Network Protocols

1.4Network Security

1.4.1Forms of Attack

1.4.2Malware

1.4.3Social Engineering

1.4.4Phishing

1.4.5Common Active Attacks

1.4.6Information Security

1.4.7SQL Injection

1.4.8Network Administration

1.4.9Protecting Against Malware

1.4.10Authentication & Passwords

1.4.11Encryption

1.4.12End of Topic Test - Networks

1.5Systems Software

1.5.1Types of System Software

1.5.2Operating Systems

1.5.3Operating System Managers

1.5.4File Management

1.5.5Device Management

1.5.6User Management

1.5.7Utility Software: Encryption & Defragmentation

1.5.8Utility Software: Data Compression & Backup

1.6Ethical, Legal, Cultural & Environmental Concern

1.6.1Open Source vs Proprietary Software

1.6.2Licensing Issues

1.6.3Ethical Issues

1.6.4Ethical Issues 2

1.6.5Exam-Style Questions - Ethical Issues

1.6.6Legal Issues

1.6.7Legal Issues 2

1.6.8Freedom of Information Act (2000)

1.6.9Cultural Issues

1.6.10Environmental Issues

1.6.11Positive Environmental Impact

1.6.12Privacy Issues

1.6.13Stakeholders

1.6.14End of Topic Test - Software & Issues

2Computational Thinking, Algorithms and Programming

2.1Algorithms

2.1.1Computational Thinking

2.1.2Algorithmic Thinking

2.1.3Pseudocode & Flow Diagrams

2.1.4Interpreting & Correcting Algorithm

2.1.5Completing Algorithms

2.1.6Search Algorithms

2.1.7Binary Search

2.1.8Overview of Sort Algorithms

2.1.9Bubble Sort & Insertion Sort

2.1.10Merge Sort

2.1.11Exam-Style Questions - Sorting Algorithms

2.2Programming Fundamentals

2.2.1Fundamentals

2.2.2Program Flow 1

2.2.3Program Flow 2

2.2.4Arithmetic & Relational Operators

2.2.5Boolean Operators

2.2.6Data Types

2.2.7Arrays

2.2.8Strings

2.2.9File Handling

2.2.10Structuring Data

2.2.11End of Topic Test - Programming

2.2.12Exam-Style Questions - Translation

2.3Producing Robust Programs

2.3.1Defensive Design Considerations

2.3.2Defensive Design Considerations 2

2.3.3Maintainability

2.3.4Testing

2.3.5Test Plans

2.3.6Error Types

2.3.7End of Topic Test - Programming

2.3.8Exam-Style Questions - Testing

2.4Boolean Logic

2.4.1Computational Logic

2.4.2Boolean Logic

2.4.3Boolean Operators

2.4.4Grade 9 - Logic

2.5Programming Languages & IDEs

2.5.1High-Level vs Low-Level Languages

2.5.2Translation - Compliers & Interpreter

2.5.3Translation - Assemblers

2.5.4Integrated Development Environments

2.5.5Exam-Style Questions - Translation

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