Question 1
A messaging app must show text in many languages and emojis. Why does it use Unicode rather than ASCII?
IGCSE Computer Science Paper 1: computer systems
Short-answer and structured questions on topics 1 to 6. Most marks are for precise knowledge, then for applying it to the system in the question.
| Topics | 1 to 6: data, transmission, hardware, software, the internet, emerging technologies |
|---|---|
| Time | 1 hour 45 minutes for 75 marks |
| Weight | 50% of the grade |
| Calculator | Not allowed |
Check your working: Binary to denary converter · Binary addition calculator · File size calculator
What the questions ask
- Working: convert between binary, denary and hexadecimal, add binary numbers, shift them, use two's complement and work out file sizes in the unit asked.
- Describe and explain: how a method or a device works, step by step, one creditable point per mark.
- Apply: choose a device, a method of transmission or a security measure for the scenario, and say why it suits that scenario.
Earning the marks
Each mark needs a separate, precise point. A describe question wants the steps in order; an explain question wants a reason or a consequence. Answers that fit any computer, not the one in the question, often miss application marks.
Try 4 questions
Question 2
| Row | Bit 1 | Bit 2 | Bit 3 | Bit 4 | Bit 5 | Bit 6 | Bit 7 | Bit 8 |
|---|---|---|---|---|---|---|---|---|
| Byte 1 | 1 | 0 | 1 | 1 | 0 | 1 | 0 | 0 |
| Byte 2 | 1 | 1 | 0 | 1 | 1 | 0 | 1 | 1 |
| Byte 3 | 1 | 0 | 0 | 1 | 0 | 1 | 1 | 0 |
| Byte 4 | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 1 |
| Byte 5 | 0 | 0 | 1 | 0 | 1 | 1 | 1 | 0 |
| Byte 6 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 |
| Parity byte | 1 | 1 | 0 | 0 | 0 | 1 | 1 | 0 |
A block of six bytes is sent with even parity. Bit 1 of each byte is that byte's parity bit, and the parity byte holds an even parity bit for each column. One bit was changed on the way. Which bit is it?
Question 3
What is the role of the central processing unit (CPU) in a computer?
Question 4
A program tries the password aaaa, then aaab, then aaac, and so on, until it gets into an account. What is this attack?
Next step
Questions people ask
Is there a multiple-choice paper?
No. Both papers are written. Our multiple-choice checks are for testing knowledge and working quickly.
Which units are used for file sizes?
The syllabus uses binary prefixes: 1 KiB is 1024 bytes and 1 MiB is 1024 KiB.