A two-hour active-recall session across the Computer Systems unit. Work from memory first, then reveal the answer and correct your own work in a different colour.
10–15 minTechnique + model
45 minRetrieval practice
40 minPast papers
10 minWeak-topic triage
01 · 10–15 min
Active recall
Active recall means trying to bring an answer out of memory before looking at notes. The struggle is useful: it shows what is secure and what needs another pass. A reveal is for checking, not for copying.
Use the same three moves every time.
1 · RetrieveWrite everything you can remember with notes closed.
2 · RevealOpen the answer only after a genuine attempt.
3 · RepairAdd missing mark points in another colour.
Worked model · 2024 Higher Q52 marks
Computer performance is improved by the inclusion of cache memory on the same computer chip as the processor. Describe how cache memory improves performance.
Mark scheme check
Cache has a faster access time than main memory.
It stores frequently used data and instructions, reducing the need to access main memory.
For two marks, the answer needs both the stored content and the reason this improves performance.
Source: SQA 2024 Higher Computing Science question paper Q5 and marking instructions.
02 · 45 min
Block 1 — retrieval practice
Spend about eight minutes on each card: write from memory first, then use the remaining time to check and repair. The reveal answers reproduce the teaching points from the linked site lessons.
CS4 · ASCII and Unicode
Compare ASCII, extended ASCII and Unicode. Include bit widths, capacity, advantages and storage implications.
Check for these points
ASCII uses 7 bits, giving 128 code points, and is normally stored in one byte.
Extended ASCII uses 8 bits and represents 256 characters, but different versions used the extra values differently.
Unicode assigns code points to characters across human writing systems. In this course, 16-bit and 32-bit Unicode use 2 or 4 bytes per character.
The first 128 Unicode code points match ASCII. Unicode supports far more characters but may require more storage.
Compare bitmap and vector graphics, then write the formula for an uncompressed bitmap file size.
Check for these points
A bitmap stores a rectangular grid of pixels. It is suitable for photographs and complex colour detail, but enlarging it can cause pixelation.
A vector stores mathematical descriptions of objects and their attributes. It scales without losing quality and suits logos or diagrams, but is unsuitable for photographic detail.
File size in bits = width × height × colour depth. Divide by 8 for bytes, then by 1,024 for KiB and again for MiB.
Increasing resolution or colour depth increases both image quality and file size.
Explain the roles of the control unit, ALU, registers, address bus, data bus and control bus.
Check for these points
The control unit decodes instructions and sends control signals to coordinate components.
The ALU performs arithmetic and logical operations.
Registers are small, fast storage locations inside the processor for immediate instructions, addresses, data and results.
The address bus selects a memory location, normally from processor to memory. The data bus carries data or instructions in both directions. The control bus carries signals such as read and write.
Answer in exam style, using the number of marks as a guide. The wording below is taken from the named SQA question papers; reveal panels are based on the corresponding marking instructions.
Performance
Aim for 10–12 minutes across these three short questions.
2023 Q5(b)2 marks
State one factor that can improve the performance of the fetch-execute cycle and explain why it improves performance.
Any one matched pair
Clock speed → more instructions carried out per second.
Data bus width → more bits transferred in one operation.
Cache → fewer accesses to slower main memory.
More cores → more instructions can be executed concurrently.
Explain why increasing the width of the data bus will improve the system performance.
Two linked points
A wider data bus allows more bits to be fetched in a single operation.
SQA Higher Computing Science specimen question paper Q11(b), marking instructions.
2018 Q92 marks
The increased use of cache memory is one trend that improves the performance of modern computer architecture.
(a) State one other trend that improves performance.
(b) Describe how your answer to part (a) improves performance.
One trend + matching effect
More processor cores → simultaneous execution or parallel processing.
Wider data bus → more bits transferred in a single operation.
Higher clock speed → more fetch-execute cycles per second.
Bailey’s Dog Kennels installed an intelligent heating system. Describe one environmental benefit to using a heating system which is intelligent.
One valid benefit
For example: the system can switch heating on or off automatically, respond to outside weather, use historical data, or heat separate zones, reducing unnecessary energy use.
Aim for 15 minutes. Keep legal offences, attack behaviour and encryption roles precise.
2024 Q9(d)2 marks
The company has been the target of a Denial of Service (DOS) attack involving resource starvation.
(i) Describe what is meant by a resource starvation DOS attack.
(ii) State one cost to the company as a result of a DOS attack.
One mark each
System resources such as the processor, RAM or backing storage are exhausted or fully used.
A cost may be lost revenue, repair of attack damage, or prevention of future attacks.
An employee has acquired their manager’s login details without permission. The employee uses the details to increase their monthly sales bonus. State two ways in which the Computer Misuse Act has been breached.
Any two
Unauthorised access.
Unauthorised access with intent to commit a further offence.
Use the evidence from this session. Be specific: “resource starvation DOS answers” is more useful than “security”. These are private take-home revision targets and are not submitted.