OxfordAQA IGCSE Computer Science: Computer Systems — Practice Questions (9210)

These are original questions written for Marlbridge, for revision and practice on this content. They are not reproduced past-paper questions, and they do not replicate the exam’s exact structure, question count or mark tariffs — examination boards hold copyright in their own papers. Use these alongside the official past papers available free from your board.

Related: Computer systems study guide | Computer systems revision notes

These questions cover section 3.4 of the OxfordAQA International GCSE Computer Science (9210) specification, which is assessed on Paper 2. Boolean expressions use the 9210 notation: NOT A is written “NOT A” here (a bar over A in the exam), A · B for AND and A + B for OR.

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Section A: hardware, software and Boolean logic

1. Define hardware and software and explain the relationship between them. [3]

2. Complete the truth table for the expression Q = NOT A + B. [2]

A	B	NOT A	Q
0	0
0	1
1	0
1	1

3. A circuit has inputs A, B and C. A and B go into an OR gate. The output of the OR gate and C go into an AND gate, whose output is Q. (a) Write a Boolean expression for Q. [1] (b) Complete a truth table for the circuit. [3] (c) State the input combinations that give Q = 1. [1]

4. A greenhouse fan (F) must switch on when the temperature is high (T = 1) and the window is not open (W = 0), or when the manual switch is pressed (M = 1). (a) Write a Boolean expression for F. [2] (b) Describe the logic circuit that implements it, using only NOT, AND and OR gates. [2]

Section B: software

5. Explain the difference between system software and application software, giving one example of each. [4]

6. State four things that an operating system manages. [4]

7. Describe the purpose of two different utility programs. [4]

Section C: systems architecture

8. Explain what is meant by the Von Neumann architecture. [2]

9. Describe the role of the ALU, the control unit and the clock. [3]

10. Describe the three stages of the fetch-execute cycle. [3]

11. A computer’s CPU is upgraded from 2.4 GHz to 3.6 GHz, and its cache is increased. Explain how each change affects performance. [4]

12. Explain why adding more processor cores may not make every program run faster. [2]

Section D: memory and storage

13. (a) Explain the terms volatile and non-volatile. [2] (b) State two differences between RAM and ROM. [2] (c) Explain why a computer needs secondary storage. [2]

14. Describe how data is stored and read on (a) magnetic storage (b) optical storage. [4]

15. A field researcher needs storage for a laptop that is carried outdoors every day. Recommend solid state, magnetic or optical storage and justify your choice. [3]

16. A school is considering moving students’ work from its own file server to cloud storage. Discuss two advantages and two disadvantages. [4]

17. Explain what an embedded system is and give one example of an embedded system and one of a non-embedded system. [3]

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Answers

1. Hardware: the physical components of a computer system [1]. Software: the programs that run on the hardware [1]. Hardware needs software to tell it what to do, and software needs hardware to run on [1].

2.

A	B	NOT A	Q
0	0	1	1
0	1	1	1
1	0	0	0
1	1	0	1

NOT A column [1]; Q column [1].

3. (a) Q = (A + B) · C [1]. (b)

A	B	C	A + B	Q
0	0	0	0	0
0	0	1	0	0
0	1	0	1	0
0	1	1	1	1
1	0	0	1	0
1	0	1	1	1
1	1	0	1	0
1	1	1	1	1

All eight input rows [1]; A + B column [1]; Q column [1]. (c) (A, B, C) = (0, 1, 1), (1, 0, 1) and (1, 1, 1) – C must be 1 and at least one of A, B must be 1 [1].

4. (a) F = (T · NOT W) + M [2] (1 for T · NOT W, 1 for + M). (b) W goes through a NOT gate; its output and T go into an AND gate [1]; the AND output and M go into an OR gate, whose output is F [1].

5. System software manages the computer system’s resources and acts as a platform for running application software [1], e.g. an operating system [1]. Application software performs end-user tasks [1], e.g. a spreadsheet [1].

6. Any four: the processor(s); memory; input/output devices; applications; security [4].

7. Any two, described [2 each]: antivirus – scans files and memory for malware and removes or quarantines it; backup – copies files so they can be restored if lost; disk defragmenter – rearranges files on a hard disk so each is stored in one place, speeding up access; compression – reduces file sizes to save space.

8. Program instructions and data are stored together in the same main memory [1], and the CPU fetches the instructions from memory and executes them one after another [1].

9. ALU: performs arithmetic and logical operations [1]. Control unit: decodes instructions and sends control signals to coordinate the other components [1]. Clock: sends regular pulses to keep the components synchronised [1].

10. Fetch: the next instruction is fetched to the CPU from main memory [1]. Decode: the instruction is decoded to work out what it is [1]. Execute: the instruction is carried out, which may involve reading from or writing to main memory [1].

11. Clock speed: 3.6 GHz gives 3.6 billion cycles per second instead of 2.4 billion [1], so more instructions can be fetched and executed each second [1]. Cache: more frequently used instructions and data can be kept in very fast memory close to the CPU [1], so it waits less often for slower main memory [1].

12. Extra cores only help if the program can be split into tasks that run at the same time [1]; some tasks must be done in order, so only one core can work on them [1].

13. (a) Volatile memory loses its contents when the power is switched off [1]; non-volatile memory keeps its contents without power [1]. (b) Any two: RAM is volatile, ROM is non-volatile; RAM can be read and written, ROM is read-only; RAM holds the programs and data in use, ROM holds the start-up instructions [2]. (c) RAM is volatile, so anything not saved to non-volatile storage is lost when the power is off [1]; main memory is also too small to hold all programs and files permanently [1].

14. (a) A read/write head magnetises tiny areas of a spinning platter in one of two directions to represent 0s and 1s [1]; when reading, the head detects the direction of magnetisation [1]. (b) A laser reads the disc as it spins [1]; pits and lands on the surface reflect the light differently, and the changes are interpreted as binary data [1].

15. Solid state [1]: it has no moving parts, so it is not damaged by being knocked or dropped outdoors [1]; it is also fast, light and uses little power, which helps battery life [1].

16. Advantages (any two): files can be accessed from any device with an Internet connection, including at home; no need to buy and maintain a local server; the provider handles backups; easy sharing between students and teachers [2]. Disadvantages (any two): no access without an Internet connection; ongoing subscription costs; the school has less control over where data is stored and its security, which matters for students’ personal data [2].

17. An embedded system is a computer built into a larger device to perform a dedicated function [1], unlike a general-purpose computer that runs many programs [1]. Example: a washing machine controller (embedded) and a desktop PC (non-embedded) [1].

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Where marks are usually lost

• Truth tables with missing or repeated rows – list inputs in binary order (000 to 111).
• Writing the Boolean expression with brackets in the wrong place, which changes the logic.
• Explaining clock speed as “how fast the computer is” without saying cycles or instructions per second.
• Recommending a storage device without referring to the user’s situation.

Frequently asked questions

Do I need to know NAND, NOR or XOR for 9210? No. The specification states that students do not need to know or use NAND, NOR and XOR gates. Circuits use only NOT, AND and OR, with up to three inputs.

What counts as main memory in 9210? Any memory directly accessible by the CPU, apart from cache and registers. Secondary storage is non-volatile and not directly accessible by the CPU.