OCR A-Level Computer Science
Explore your course, one topic at a time.
Course overview
The OCR A-Level Computer Science specification covers 37 topics with 406 learning objectives (H446). Use the topic browser below to explore subtopics, exam tips, common mistakes, and key terminology for each area of the course.
- 37 topics
- 1 study page
- 406 learning objectives
- 810
- practice questions
- 135
- teaching notes
- 37
- topics
Your exams
- Computer systemsMonday, 7 June 2027, PM
- Algorithms and programmingTuesday, 15 June 2027, AM
Always confirm dates and times with your exam centre.
| Paper | Time | Marks | Weight |
|---|---|---|---|
| Computer systems | 150 min | 140 | 40% |
| Algorithms and programming | 150 min | 140 | 40% |
| Programming project | - | 70 | 20% |
| Programming project | - | 70 | 20% |
Explore your topics
37 topics
Computer systems16 topics
- Structure and function of the processor5 specification points covering (a) The Arithmetic and Logic Unit; ALU, Control Unit and Registers (Program Counter; PC, Accumulator; ACC, Memory Address…15 objectives
- Types of processor3 specification points covering (a) The differences between and uses of CISC and RISC processors., (b) GPUs and their uses (including those not related to…9 objectives
- Input, output and storage4 specification points covering (a) How different input, output and storage devices can be applied to the solution of different problems., (b) The uses of…12 objectives
- Systems Software8 specification points covering (a) The need for, function and purpose of operating systems., (b) Memory Management (paging, segmentation and virtual…24 objectives
- Applications Generation6 specification points covering (a) The nature of applications, justifying suitable applications for a specific purpose., (b) Utilities., (c) Open source vs…18 objectives
- Software Development3 specification points covering (a) Understand the waterfall lifecycle, agile methodologies, extreme programming, the spiral model and rapid application…9 objectives
- Types of Programming Language5 specification points covering (a) Need for and characteristics of a variety of programming paradigms., (b) Procedural languages., (c) Assembly language…15 objectives
- Compression, Encryption and Hashing4 specification points covering (a) Lossy vs Lossless compression., (b) Run length encoding and dictionary coding for lossless compression., (c) Symmetric…12 objectives
- Databases6 specification points covering (a) Relational database, flat file, primary key, foreign key, secondary key, entity relationship modelling, normalisation…18 objectives
- Networks5 specification points covering (a) Characteristics of networks and the importance of protocols and standards., (b) The internet structure: • The TCP/IP Stack.15 objectives
- Web Technologies4 specification points covering (a) HTML, CSS and JavaScript.12 objectives
- Data Types10 specification points covering (a) Primitive data types, integer, real/floating point, character, string and Boolean., (b) Represent positive integers in…30 objectives
12 of 16 shown
Algorithms and programming8 topics
- Thinking abstractly4 specification points covering (a) The nature of abstraction., (b) The need for abstraction., (c) The differences between an abstraction and reality.12 objectives
- Thinking ahead4 specification points covering (a) Identify the inputs and outputs for a given situation., (b) Determine the preconditions for devising a solution to a…12 objectives
- Thinking procedurally4 specification points covering (a) Identify the components of a problem., (b) Identify the components of a solution to a problem., (c) Determine the order…12 objectives
- Thinking logically3 specification points covering (a) Identify the points in a solution where a decision has to be taken., (b) Determine the logical conditions that affect…9 objectives
- Thinking concurrently2 specification points covering (a) Determine the parts of a problem that can be tackled at the same time., (b) Outline the benefits and trade offs that…6 objectives
- Programming techniques6 specification points covering (a) Programming constructs: sequence, iteration, branching., (b) Recursion, how it can be used and compares to an iterative…19 objectives
- Computational methods6 specification points covering (a) Features that make a problem solvable by computational methods., (b) Problem recognition., (c) Problem decomposition.18 objectives
- Algorithms6 specification points covering (a) Analysis and design of algorithms for a given situation., (b) The suitability of different algorithms for a given task…18 objectives · 1 study page
Programming project13 topics
- Problem identification2 specification points covering (a) Describe and justify the features that make the problem solvable by computational methods., (b) Explain why the problem…6 objectives
- StakeholdersThis criterion asks you to identify the people with an interest in your solution, describe each interest, and explain how the solution suits their needs.3 objectives
- Research the problem3 specification points covering (a) Research the problem and solutions to similar problems to identify and justify suitable approaches to a solution., (b)…9 objectives
- Specify the proposed solution2 specification points covering (a) Specify and justify the solution requirements including hardware and software configuration (if appropriate)., (b)…6 objectives
- Decompose the problemThis statement asks you to break the problem into smaller parts, make sure each part is suitable for a computational solution, and justify the decisions you…3 objectives
- Describe the solution4 specification points covering (a) Explain and justify the structure of the solution., (b) Describe the parts of the solution using algorithms justifying…12 objectives
- Describe the approach to testingThis statement asks you to name the test data you will use during iterative development and after development is complete, then justify each choice.3 objectives
- Iterative development process2 specification points covering (a) Provide annotated evidence of each stage of the iterative development process justifying any decision made., (b) Provide…6 objectives
- Testing to inform development2 specification points covering (a) Provide annotated evidence for testing at each stage justifying the reason for the test., (b) Provide annotated evidence…6 objectives
- Testing to inform evaluation2 specification points covering (a) Provide annotated evidence of testing the solution of robustness at the end of the development process., (b) Provide…6 objectives
- Success of the solutionUse means you must draw on test evidence rather than assert that the solution works.3 objectives
- Describe the final productThis criterion asks you to provide annotated evidence of the usability features from your design, as built in the final solution, and to comment on how…3 objectives
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About this course
About OCR A-Level Computer Science
OCR A-Level Computer Science dives deep into the heart of how computers and software work, and how to solve problems through computational thinking. You'll explore the science behind the screen: from the inner workings of processors and data representation, to how networks and databases function in modern systems. The course balances theory with practical programming, encouraging you to think like a computer scientist—analysing issues, designing algorithms, and writing efficient code.
Structured around two main themes, 'Computer Systems' and 'Algorithms and Programming', the specification gives you a thorough understanding of both hardware and software. You'll study the characteristics of contemporary systems, software development methodologies, and the exchange and storage of data. Alongside, you'll develop your programming skills using a high-level language, learning to apply standard algorithms and data structures to tackle complex problems.
A standout feature is the Programming Project, where you'll independently research, design, develop, and evaluate a software solution for a real-world problem of your choice. This coursework component allows you to showcase your creativity and technical ability, producing a substantial portfolio that universities and employers highly value. Throughout the course, you'll also consider the ethical, legal, and cultural impacts of digital technology, preparing you to be a responsible digital citizen.
Assessment Structure
The qualification is assessed through three components: two written exam papers and a non-exam assessment. Paper 1 (Computer Systems) and Paper 2 (Algorithms and Programming) are both 2 hours 30 minutes long, each worth 140 marks and 40% of the final A-Level. Paper 1 covers the theoretical aspects of computing, while Paper 2 focuses on problem-solving, algorithms, and coding skills with a mix of short and extended response questions, including a scenario-based task. The Programming Project (non-exam assessment) is worth 70 marks, contributing the final 20%. It is internally assessed by your teacher and externally moderated by OCR. Total marks available across the course are 350.
Why Choose OCR?
- OCR's A-Level Computer Science offers a well-balanced mix of theory and hands-on programming, making it ideal for students who want to understand both the 'why' and the 'how' of computing. The substantial programming project (20% of the grade) gives you the freedom to create a meaningful software solution, which can be a fantastic portfolio piece for university applications or apprenticeships in tech.
- The specification is highly regarded for its clarity and depth, with a logical structure that builds your knowledge progressively. Detailed teaching resources and past papers are readily available, making revision straightforward. The emphasis on computational thinking and mathematical skills also provides excellent preparation for STEM degrees, particularly Computer Science, Engineering, and Mathematics.
- Compared to other boards, OCR places a stronger emphasis on the theoretical underpinnings of computer science, such as Boolean algebra, data structures, and the complexities of system architecture. This academic rigour is valued by top universities and gives you a deeper, more robust understanding that goes beyond just learning to code.
Frequently Asked Questions
What programming language do I need to learn for OCR A-Level Computer Science?
How is the Programming Project assessed and what makes a good project?
Is OCR A-Level Computer Science harder than other exam boards?
Do I need to have studied Computer Science at GCSE to take this A-Level?
What resources does OCR provide to help with revision and exam preparation?
Assessment and exam guidance
Assessment Objectives
Demonstrate knowledge and understanding of the principles and concepts of computer science, including abstraction, logic, algorithms and data representation
Apply knowledge and understanding of the principles and concepts of computer science including to analyse problems in computational terms
Design, program and evaluate computer systems that solve problems, making reasoned judgements about these and presenting conclusions
Exam Structure
Computer systems
2h 30m
Duration
140
Marks
40%
Weighting
Algorithms and programming
2h 30m
Duration
140
Marks
40%
Weighting
Programming project
Not stated
Duration
70
Marks
20%
Weighting
Programming project
Not stated
Duration
70
Marks
20%
Weighting
Tips and common mistakes
Common Exam Mistakes
Pitfalls to avoid in your exams
- •Confuses the MAR with the MDR; the MAR holds the address being accessed, while the MDR holds the data being transferred.
- •Describes the ACC as holding the next instruction's address; the PC holds that address and the ACC holds results.
- •Treats the control bus as carrying data; the data bus carries data, while the control bus carries signals such as read and write.
- •Places the instruction in the CIR before it has been fetched from memory; the instruction passes through the MDR first, then reaches the CIR.
- •Describes the PC as being incremented after execution; the PC is incremented during fetch.
- •Treats decode as carrying out the instruction; decode only interprets the opcode, and the ALU performs the operation in execute.
- •Treats clock speed as the only factor that determines performance; state that the number of cores and the cache also affect it.
- •Assumes four cores make a program four times faster; state that only tasks that can run in parallel gain close to that speedup.
Top Examiner Tips
Expert advice for exam success
- •Learn each register through one purpose statement, such as what kind of value it stores, and check each MCQ option against it.
- •When an option names a bus, ask whether the item is data, an address or a control signal before accepting it.
- •Trace a short assembly instruction through the registers and buses to test options that link hardware to assembly language.
- •Write the register transfers in order (PC to MAR, memory to MDR, MDR to CIR) and check each MCQ option against that sequence.
- •Remember that a branch instruction changes the PC, while a normal instruction only increments it.
- •For each option, check which register changes at each stage before accepting it.
- •Give each of the three factors its own paragraph containing a mechanism, an example and a limitation.
- •Convert units before calculating: 3.5 GHz means 3.5 × 10⁹ cycles per second, so the cycle time is 1 ÷ (3.5 × 10⁹) s.
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