Number Bases

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Binary

In everyday life, we use the denary number system. Computers use binary instead.

Denary

In everyday life, we use a denary number system.
We use 10 symbols to represent each digit.
Each digit's place value is multiplied by 10 as we move from right to left.

Binary

Binary is an identical system, except using two symbols for each digit.
Only 1 and 0 are used in binary.
Each digit's place value is multiplied by two as we move from right to left.

Hexadecimal

Hexadecimal uses 16 different symbols for each place.
Hexadecimal uses the digits 0-9 then A-F:
- A = 10 in denary, B = 11 ...
Each digit's place value is multiplied by 16 as we move from right to left.

Converting Binary and Hexadecimal

Both binary and hexadecimal can be used to represent the same number, so it's important to be able to convert between them.

Binary to hexadecimal

Binary can be converted to hexadecimal by grouping into groups of 4 bits:
- Start grouping from the right-hand side.
- Convert each 4 bit group separately.

Hexadecimal to binary

Hexadecimal can be converted to binary by splitting each digit into 4 bits:
- Separately convert each hexadecimal digit into 4 bits of binary.
- Put all of the 4 bit groups together.

Converting Denary and Hexadecimal

Both denary and hexadecimal can be used to represent the same number, so it's important to be able to convert between them.

Denary to hexadecimal

The easiest method to convert denary numbers to hexadecimal is to first convert the denary to binary, and then use the binary to hexadecimal conversion algorithm.

Hexadecimal to denary

To convert from hexadecimal to denary, you should:
- Write out the powers of 16 above each hexadecimal digit.
- For each place column, multiply the hexadecimal digit by the power of 16 above it.
- Add together all of these results.

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

1.3Computer Networks, Connections & 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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