Cambridge International AS & A Level Computer Science (9618)
From logic gates to artificial intelligence, from assembly language to object-oriented programs — A Level Computer Science teaches you how computers really work and how to make them do remarkable things.
Checked against the official Cambridge syllabus for exams in 2026 and 2027–2029 (same papers) · 18 October 2026
1.Quick facts
2.Why study Computer Science?
Cambridge designs 9618 so that you can:
- Understand the principles of computer science — abstraction, logic, algorithms and data representation.
- Analyse problems in computational terms.
- Design, program and test solutions — and evaluate them with reasoned judgements.
- Think creatively through practical programming.
- Move on confidently to a computing, engineering or data-science degree.
Based on the syllabus overview and assessment objectives.
3.Why these topics?
How computers represent and move data
Binary, two's complement, multimedia and compression, then floating-point numbers. Networks, the internet, protocols and packet switching — how a video call reaches you.
Hardware down to the gates
Logic gates and circuits, the CPU and assembly language, then Boolean algebra, RISC processors, parallel processing and virtual machines.
Software, security and ethics
Operating systems and translators, data security and integrity, ethics and ownership — then encryption protocols and digital certificates that keep the internet trustworthy.
Databases
Design relational databases and use SQL to define and query them — how every app stores its users and data.
Problem-solving and programming
Algorithms, data structures and the program development life cycle at AS; then recursion, stacks, queues, linked lists, binary trees, object-oriented and other programming paradigms, and exception handling.
Artificial intelligence
Graphs, A* and Dijkstra's algorithms, and the categories of machine learning, including deep learning — the ideas behind route-finding apps and modern AI.
4.Topic map
AS Level
- 1Information representation
- 2Communication
- 3Hardware
- 4Processor Fundamentals
- 5System Software
- 6Security, privacy and data integrity
- 7Ethics and Ownership
- 8Databases
- 9Algorithm Design and Problem-solving
- 10Data Types and Structures
- 11Programming
- 12Software Development
A Level (adds)
- 13Data Representation
- 14Communication and internet technologies
- 15Hardware and Virtual Machines
- 16System Software
- 17Security
- 18Artificial Intelligence (AI)
- 19Computational thinking and Problem-solving
- 20Further Programming
5.From O Level to A Level
Coming from O Level or IGCSE Computer Science? Here's what deepens.
| Idea | At O Level / IGCSE | At AS & A Level (this course) |
|---|---|---|
| Data | Binary, hex, file sizes | Two's complement, floating-point, user-defined types, file organisation |
| Hardware | CPU basics, logic gates | Assembly language, Boolean algebra, RISC, parallel processing |
| Programming | Pseudocode, arrays, files | ADTs, recursion, OOP, exceptions — and a practical exam on a computer |
| Databases | Simple SQL queries | Normalisation, DDL and DML |
| AI | What AI is | Graph algorithms (A*, Dijkstra) and machine learning |
6.Exam pattern
All papers are marked by Cambridge. Calculators must not be used in any paper. Paper 4 needs an exam centre that can run it on computers.
7.Types of questions
Examples are written by our teachers in Cambridge style to show the type of question — they are not copied from past papers.
8.Command words
| Word | Cambridge meaning | What to do |
|---|---|---|
| Describe | state the points of a topic / give characteristics and main features | Step by step, with correct terms. |
| Explain | set out purposes or reasons / make the relationships between things clear / say why and/or how and support with relevant evidence | Say why or how — not just what. |
| Complete | add information to an incomplete diagram or table | Trace tables, truth tables, diagrams. |
| Compare | identify/comment on similarities and/or differences | Both items in each point. |
| Evaluate | judge or calculate the quality, importance, amount, or value of something | Weigh up, then conclude. |
| Analyse | examine in detail to show meaning, identify elements and the relationship between them | Break the problem into parts. |
Meanings are quoted from the 'Command words' table in the official syllabus.
9.What examiners reward
At full A Level, designing and programming solutions is the biggest single objective (40%).
10.Grades
AS Level: a, b, c, d, e. Full A Level: A*, A, B, C, D, E.
What it took in June 2026 (full A Level, four papers)
| Grade | Marks out of 300 | Roughly |
|---|---|---|
| A* | 240–250 | about 80–83% |
| A | 206–216 | about 69–72% |
| B | 172–182 | about 57–61% |
| C | 142–153 | about 47–51% |
| D | 112–124 | about 37–41% |
| E | 83–96 | about 28–32% |
Minimum marks out of 300 in June 2026; the range covers the different paper variants. For AS Level alone (out of 150) an 'a' needed about 99–109.
Computer science and software engineering degrees often ask for Computer Science with A Level Mathematics.
11.Programming practice
- Choose Python, Java or Visual Basic (.NET) early and use it for everything — Paper 4 is done in console mode.
- Master the Cambridge pseudocode format for Paper 2 (it's in the syllabus).
- Implement every data structure yourself: stack, queue, linked list, binary tree.
- Practise reading from and writing to text files, and handling exceptions.
- Always test with normal, abnormal and extreme/boundary data — Paper 4 asks for evidence of testing.
12.Books & resources
Cambridge says textbooks endorsed for the syllabus from 2021 are still suitable for 2027–2029.
13.Common mistakes
- Writing Python syntax in Paper 2 instead of Cambridge pseudocode.
- Forgetting base cases in recursion.
- Mixing up stacks (LIFO) and queues (FIFO).
- Submitting Paper 4 code without the required testing evidence.
- Memorising definitions without being able to apply them to a scenario.
Tips from our teachers.
14.Study plan
- Year 1 (AS), term 1Information representation, communication, hardware (1–3); pseudocode basics (9, 11).
- Year 1, term 2Processor fundamentals, system software, security, ethics (4–7); data types and structures (10).
- Year 1, term 3Databases and SQL (8); software development (12); AS past papers.
- Year 2 (A2), term 1Data representation, networks, hardware, system software, security (13–17).
- Year 2, term 2AI (18); computational thinking and further programming (19–20); Paper 4 practice on a computer.
- Final monthsTimed Papers 3 and 4; build and test one complete program a week.
Cambridge designs AS for about 180 and full A Level for about 360 guided learning hours — plus lots of coding.
15.Where it can take you
A Level Computer Science leads straight into the technology industry.
Typical subject requirements — always check each university's own entry rules.
16.Computer Science in the real world
Route-finding apps
Map apps find the fastest route using graph algorithms like A* and Dijkstra's — Topic 18.
The padlock in your browser
Digital certificates and encryption protocols (Topic 17) are why you can trust online banking.
Al-Khwarizmi
The word 'algorithm' comes from his name; Topic 9 is all about algorithms.
Machine learning
Recommendation systems and voice assistants use machine learning — the syllabus asks you to understand its categories, including deep learning.
17.Frequently asked questions
Do I need O Level Computer Science first?
Cambridge recommends a course equivalent to IGCSE or O Level Computer Science.
Which language for Paper 4?
Java, Visual Basic (any .NET version, not VB6) or Python, in console mode.
How is Paper 4 taken?
On a computer without internet or email. You submit complete program code and evidence of testing. Your exam centre must be able to run it.
Calculator?
Calculators must not be used in any paper.
Is the syllabus changing?
The 2027–2029 syllabus has no significant changes that affect teaching.
18.Study it with us
Live online classes with experienced Cambridge teachers, weekly quizzes and assignments in your portal, past-paper practice, and progress reports your parents can see.
19.Official sources
- Official syllabus 9618 for exams in 2026 (PDF)
- Official syllabus 9618 for exams in 2027, 2028 and 2029 (PDF)
- Grade threshold table, June 2026 (PDF)
- Endorsed resources for 9618
Cambridge says its syllabuses and specimen materials are the final authority on the content and structure of its exams. Always check you are using the syllabus for the year you sit the exam.