OCR GCSE Computer Science (J277): complete guide to the topics and the two exams

OCR GCSE Computer Science (specification J277) is assessed by two equally weighted written papers sat at the end of the course. There is no formally assessed coursework or NEA, although you must gain practical programming experience during the course. This page is the index: below is a map of the two components, the exam structure, and how to study each one.

The two OCR J277 components (1.1-2.5)

The specification has two components. Component 01 is examined in Paper J277/01; Component 02 is examined in Paper J277/02.

Component 01: Computer systems. The theory of how a computer and a network are built and run.

• 1.1 Systems architecture. The purpose and components of the CPU, the fetch-decode-execute cycle, the von Neumann architecture, the factors that affect CPU performance, and embedded systems.
• 1.2 Memory and storage. Primary storage (RAM, ROM and virtual memory), secondary storage and how to choose it, units of information, binary and hexadecimal number work, representing characters, images and sound, and compression.
• 1.3 Computer networks, connections and protocols. LANs and WANs, the factors that affect performance, network hardware and topologies, wired versus wireless connections, the common protocols, and the four-layer TCP/IP model.
• 1.4 Network security. The forms of attack on a system or network, and the methods used to identify and prevent them.
• 1.5 Systems software. The purpose and functions of the operating system, and the common utility software.
• 1.6 Ethical, legal, cultural and environmental impacts. The issues raised by digital technology, the relevant legislation, and privacy.

Component 02: Computational thinking, algorithms and programming. Designing, writing, tracing and reasoning about programs.

• 2.1 Algorithms. Computational thinking (abstraction, decomposition, algorithmic thinking), designing and refining algorithms with pseudocode and flowcharts, and the standard searching (linear, binary) and sorting (bubble, insertion, merge) algorithms.
• 2.2 Programming fundamentals. Variables and constants, the three constructs (sequence, selection, iteration), data types and operators, arrays, string handling and file handling, and sub-programs.
• 2.3 Producing robust programs. Defensive design and input validation, maintainability, and the types of testing and test data.
• 2.4 Boolean logic. AND, OR and NOT in expressions, truth tables and logic gate diagrams.
• 2.5 Programming languages and IDEs. High-level versus low-level languages, translators (compiler, interpreter, assembler), and the features of an integrated development environment.

Exam structure

OCR GCSE Computer Science is assessed by two written papers, both sat at the end of the course. There is no tiering: every student sits the same papers, and neither paper allows a calculator.

• Paper J277/01 (Computer systems) - 1 hour 30 minutes, 80 marks, 50%. Tests Component 01 (topics 1.1 to 1.6) with multiple-choice, short-answer and extended-response questions, including one 8-mark extended-response question.
• Paper J277/02 (Computational thinking, algorithms and programming) - 1 hour 30 minutes, 80 marks, 50%. Section A (50 marks) covers concepts and computational thinking; Section B (30 marks) is practical programming, answered in the OCR Exam Reference Language or a high-level language you know.

You must also complete practical programming experience during the course, but it does not count towards your final grade.

How to study OCR Computer Science

Computer Science rewards regular practical coding, fluent number work, and precise definitions.

1. Work from the specification statements. Each numbered topic (for example 1.1 Systems architecture) is a checklist; questions are written from them.
2. Code and trace regularly. Section B of Paper 2 tests writing and tracing programs, so practise the OCR Exam Reference Language rather than only reading.
3. Drill the number work. Binary, denary and hexadecimal conversion, binary addition with overflow, and image and sound file-size calculations recur in Paper 1 and must be automatic.
4. Learn the OCR pseudocode. Exam algorithms are shown in the OCR Exam Reference Language, so learn the notation as well as your chosen language.
5. Learn definitions precisely. Mark schemes reward exact wording, for example the difference between RAM and ROM, lossy versus lossless compression, or a compiler versus an interpreter.

The two components, dot point by dot point

Each component has specification-statement-level answer pages with worked exam questions and cross-links. Browse the full set at /gcse-ocr/computer-science/syllabus.

For the official specification

OCR publishes the full specification (J277), past papers, mark schemes and the Exam Reference Language guide at ocr.org.uk. Always revise from the current specification and OCR's own past papers, because question style and the pseudocode notation are board-specific.