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Cambridge IGCSE Computer Science Past Papers
Official question papers, mark schemes and examiner reports.
84 papers18 exam sessionsFree to download
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Navigator’s note
Confusing Command Words
Check the command word before answering.
All 8 examiner tipsOther destinations
Cambridge IGCSE Computer Science papers by session
November 2025
6 papersLatest seriesPaper 2
Algorithms, Programming and Logic
0478/21
- November 2025
- Question paper
- Mark scheme
- Examiner report not available
Paper 2
Algorithms, Programming and Logic
0478/22
- November 2025
- Question paper
- Mark scheme
- Examiner report not available
Paper 2
Algorithms, Programming and Logic
0478/23
- November 2025
- Question paper
- Mark scheme
- Examiner report not available
June 2025
6 papersMarch 2025
2 papersExaminer InsightsCambridge IGCSE Computer Science
Where marks are made.
Spot the common mistake. Make the precise correction.
01Common mistake
Confusing Command Words
Students often give the wrong type of response because they misread the command word. For example, they may describe what a compiler does when the question asks them to explain when or why it would be used.
How to solve it
Check the command word before answering.
Identify usually requires a brief name or fact, describe requires you to state the main features or what happens, and explain requires you to show how or why something happens using clear reasoning.
Check the command word before you write.
02Common mistake
Using Invalid Identifiers in Programming
Students sometimes use variable, constant or array names containing spaces or invalid characters, or change the spelling or capitalisation of an identifier later in the program.
How to solve it
Use valid identifier names with no spaces, and follow a consistent naming style such as camelCase or snake_case.
Once an identifier has been declared, use exactly the same spelling and capitalisation every time it appears.
Check the command word before you write.
03Common mistake
Failure to Show Full Working in Calculations
Students sometimes give only the final answer for calculations such as binary-to-denary conversion or binary addition, without showing the steps used to reach it.
How to solve it
Always show your working clearly, including place values, conversions and carry bits where relevant.
Even if the final answer is incorrect, a correct method may still earn marks.
Check the command word before you write.
04Common mistake
Misunderstanding Security Threats and Their Targets
Students often confuse different cyber-security threats, such as phishing and pharming, or misunderstand how attacks such as Denial of Service work. For example, a DoS attack is sometimes incorrectly described as software being installed on a server.
How to solve it
Learn how each security threat works and what it targets.
Malware such as viruses and worms involves malicious software, while phishing tricks users into revealing information and pharming redirects users to fraudulent websites. A DoS attack floods a server or network with requests or traffic, making the service unavailable to legitimate users.
Check the command word before you write.
05Common mistake
Formatting Errors in Trace Tables and Outputs
Students often add values to a trace table that the algorithm has not yet assigned, or include unnecessary punctuation such as quotation marks in the output column.
How to solve it
Follow the algorithm exactly as written.
Only initialise a variable when the algorithm does so, and in the output column write exactly what would appear on the screen, without quotation marks, commas or other symbols unless they are actually part of the output.
Check the command word before you write.
06Common mistake
Misconceptions About Hexadecimal Storage
Students sometimes believe that hexadecimal is used because it requires less computer memory than binary.
How to solve it
Remember that computers ultimately store data in binary.
Hexadecimal is mainly used as a shorter, more convenient way for humans to represent and read binary values, making long binary strings easier to understand, check and debug.
Check the command word before you write.
07Common mistake
Missing Initialisation and Counter Resets
In algorithms, students often forget to initialise counters, totals or accumulators before a loop begins, causing later calculations to produce incorrect results.
How to solve it
Before using a counter or running total, check that it has been given the correct starting value, which is often zero.
Also check whether it needs to be reset before another loop or calculation begins.
Check the command word before you write.
08Common mistake
Misconceptions About Actuators
Students sometimes confuse actuators with output devices such as monitors and assume an actuator is needed to display information on a screen.
How to solve it
Remember that an actuator causes a physical action or movement, such as turning a motor, opening a valve or moving a robotic arm.
A monitor is an output device that displays information and does not require an actuator to produce an image or message.
Check the command word before you write.
Frequently asked questions
Are there any changes to Cambridge IGCSE Computer Science (0478) for 2027 compared with 2026?
No. Cambridge IGCSE Computer Science (0478) follows the same 2026–2028 syllabus, so the content, assessment objectives and paper structure remain the same in 2027. Resources designed for the 2026–2028 syllabus are therefore suitable for both years.
When was the Cambridge IGCSE Computer Science syllabus last changed?
The most recent major update to Cambridge IGCSE Computer Science (0478) took effect for the 2026–2028 exam cycle, with first examinations in 2026. The previous syllabus covered the 2023–2025 exam cycle.
How do I know if Cambridge IGCSE Computer Science (0478) is the right syllabus code for me?
Check your school registration, student portal or Statement of Entry for the syllabus code 0478. You should also make sure your resources match the 2026–2028 syllabus and are not based on an older specification. If you are unsure, confirm your exam entry code with your teacher or exams officer.
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