GCSE Computer Science Revision Notes

21 free revision notes covering every main GCSE Computer Science topic. No account needed.

Computer Science at GCSE splits into two halves that feel very different. One is theory — how a computer is built, how it moves data around a network, how it represents everything as binary. The other is problem solving: writing and tracing algorithms, and programming.

Most students find the theory easier to revise and the programming harder to improve, so they quietly practise the theory and avoid the code. That is the wrong way round. Theory marks come back quickly once the key terms are learned, but algorithm and trace-table questions only improve by working through them on paper.

Two things reliably cost marks. The first is vague definitions — writing that RAM is "memory that stores stuff" earns nothing where "volatile memory holding programs and data currently in use" earns the mark. The second is trace tables, where students work in their head rather than filling the table in row by row.

Work through the notes below topic by topic, then test yourself before you move on. Reading a page on binary is not the same as being able to convert one under time pressure.

Algorithms

Searching Algorithms Sorting Algorithms Computational Thinking

Computer Systems

Boolean Logic and Logic Gates The CPU and Fetch–Execute Cycle Memory and Storage

Data Representation

Binary and Denary Hexadecimal Binary Arithmetic and Shifts Characters, Images and Sound Compression

Impacts of Technology

Ethical, Legal and Environmental Impacts

Networks

Networks: Types and Topologies Protocols, Layers and the Internet

Programming

Programming Fundamentals Selection and Iteration Arrays, Lists and Records Subroutines: Functions and Procedures String Manipulation

System Security

Network Threats and Protection

System Software

Operating Systems and Utility Software

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