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Edexcel GCSE Computer Science (1CP2) Exam Questions

Build a practice paper from 693 exam-style questions, each with its mark scheme and example answers. Print it, or answer it on paper and then open the mark schemes. Or browse the questions by topic.

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2 questions · 4 marks

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1Describe2 marksFetch Decode Execute Cycle Swap Remove

A computer has an address bus.

Describe the purpose of the address bus in the fetch-decode-execute cycle.

[2 marks]
Mark scheme

Award up to two marks for a linked description such as:

  • Carries the address of a memory location (1) that the CPU needs to access/read from or write to (1)
  • Transfers the address of the next instruction (1) to main memory so it can be fetched (1)
  • Carries the address of data/instructions (1) from the CPU to main memory (1) so the correct location is found
  • Is used by the CPU to specify/identify a location in memory (1) by carrying its address along the bus (1)

Award one mark for a correct point even if not developed, e.g. 'it carries the address of a memory location'.

Accept 'the address of the next instruction' without mentioning the program counter, if it is linked to being sent to main memory/to be fetched.

Do not accept responses about carrying data or control signals.

Do not accept responses that say the address bus sends/transfers instructions or data without referring to addresses.

Do not accept vague responses such as 'it carries addresses' without saying what the address is for.

Example answers and how they were marked
Full marks2/2

The address bus carries the address of the next instruction from the program counter to main memory so it can be fetched.

Why: Linked point (1) and development (1): transfers the address of the next instruction to main memory to be fetched. 'From the program counter' is an accepted extra detail, not required.

Some marks1/2

The address bus carries the address of a memory location.

Why: Correct point (1) but no linked development, e.g. that the CPU needs to access it.

No marks0/2

The address bus carries data between the CPU and RAM.

Why: No creditworthy point: confuses the address bus with the data bus.

2Explain2 marksThe Internet Swap Remove

Routers on the internet choose a route for each packet.

Explain one benefit of a router being able to choose a different route for a packet.

[2 marks]
Mark scheme

Award up to two marks for a linked explanation such as:

  • Data can avoid a busy/congested link (1) because the router can choose another path (1)
  • Data can still arrive if a link fails (1) because the router sends it another way (1)
  • Data can take the shortest/fastest path (1) because the router compares the routes and chooses the one with the fewest hops/least traffic (1)

For both marks, the expansion must follow/associate with the statement.

Allow other valid benefits with a linked reason, e.g. traffic can be shared across routes/load balanced (1) because the router can send some packets by another path (1)

Do not accept 'the route is always the same' as this is not a benefit of choosing a route.

Do not accept 'routers are fast' or 'packets are sent faster' on its own: the reason must say how the route is chosen, e.g. avoiding congestion or using a routing table.

Example answers and how they were marked
Full marks2/2

If one route is busy, the data can still get there because the router can choose a different path.

Why: Linked point (1) and reason (1): a different path avoids the busy route.

Some marks1/2

It can choose the fastest route because routers are quick.

Why: Point (1) for choosing the fastest route, but 'routers are quick' is a speed statement that does not say how the route is chosen, so it does not earn the second mark.

No marks0/2

It means more devices can connect to the internet.

Why: No link to choosing a route for a packet; does not answer the question.

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