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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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3 questions · 5 marks

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1Multiple choice1 markStored Program Computers Swap Remove

Identify the bus that carries addresses in one direction only, from the CPU to main memory.

[1 mark]
  • AAddress bus
  • BControl bus
  • CData bus
  • DSystem bus
Mark scheme
  • A Address bus (1)
  • The only correct answer is A. The correct answer is address bus. Do not accept 'address' on its own.
  • B is not correct because the control bus carries control signals in both directions between the CPU and other components
  • C is not correct because the data bus carries data in both directions between the CPU and main memory
  • D is not correct because the system bus is the collection of all three buses
Example answers and how they were marked
Full marks1/1

A Address bus

Why: Correct option: the address bus carries addresses in one direction only, from the CPU to main memory (1).

No marks0/1

C Data bus

Why: The data bus carries data in both directions, so it is not the bus that carries addresses in one direction only from the CPU to main memory; no creditworthy point.

No marks0/1

B Control bus

Why: The control bus carries control signals in both directions, not addresses in one direction only; this is the common control/address bus confusion, so no mark.

2Short recall2 marksFetch Decode Execute Cycle Swap Remove

The control unit is one component of the CPU.

Give two roles of the control unit during the fetch-decode-execute cycle.

[2 marks]
Mark scheme

Award one mark for any of the following up to a maximum of two marks:

  • Decodes the instruction / works out what the instruction is (1)
  • Sends control signals to the other components (of the CPU) (1)
  • Coordinates/controls the activities of the CPU (1)
  • Directs the timing of the other components / controls when each component acts (1)

Do not accept carrying out arithmetic or logical operations, as this is the role of the ALU.

Do not accept holding/storing the data or instructions, as this is the role of the registers/main memory.

Example answers and how they were marked
Full marks2/2

It decodes each instruction and sends control signals to the other components to tell them what to do.

Why: Decodes the instruction (1) and sends control signals to the other components (1).

Some marks1/2

It decodes the instructions and carries out the calculations.

Why: Decoding the instruction (1); the calculations are carried out by the ALU, so the second part earns nothing.

No marks0/2

It stores the data that the CPU is working on.

Why: Storing data is the role of the registers/main memory, not the control unit, so no point is creditworthy.

3Explain2 marksFetch Decode Execute Cycle Swap Remove

The von Neumann architecture is used in most computers.

Explain one feature of the von Neumann stored program concept.

[2 marks]
Mark scheme

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

  • The instructions/program instructions and data are stored together in main memory/RAM (1) so the CPU can fetch each instruction (from its address) and execute it (1)
  • The instructions/program instructions are held in main memory/RAM (1) rather than being built into/part of the hardware, so the computer does not need to be rewired/rebuilt to run a different program (1)
  • The next instruction to be executed/instruction is held in main memory/RAM (1) so the CPU can fetch it using its address before it is decoded and executed (1)

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

A point/statement on its own can only earn one mark.

Do not accept a response that only refers to data being stored in main memory/RAM without referring to the instructions/program instructions.

Do not accept instructions/programs being stored on the hard disk/backing store.

Do not accept 'the program is stored in memory' without saying that it is the instructions/program instructions that are stored there.

Example answers and how they were marked
Full marks2/2

Both the instructions of the program and the data it uses are stored together in the same main memory, so the CPU can fetch each instruction in turn and execute it.

Why: Linked point (1) and reason (1).

Some marks1/2

The instructions of the program are stored in main memory.

Why: Point only (1); no linked reason about fetching/executing the instructions.

No marks0/2

The program is stored on the hard disk and is copied into the CPU when it is run.

Why: Misconception covered by the 'Do not accept' line: the instructions must be stored in main memory/RAM, not on the hard disk/backing store, for the CPU to fetch them.

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