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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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4 questions · 7 marks

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1Multiple choice1 markPrimary Memory Swap Remove

Identify what is fetched from RAM during the fetch stage.

[1 mark]
  • AThe next instruction
  • BThe data at a memory address
  • CThe decoded instruction
  • DThe address of the next instruction
Mark scheme
  • A The next instruction (1)
  • The only correct answer is A. The correct answer is the next instruction.
  • B is not correct because data is fetched during the execute stage
  • C is not correct because an instruction is decoded after it is fetched
  • D is not correct because the program counter holds the address used to fetch the instruction
Example answers and how they were marked
Full marks1/1

A The next instruction

Why: The next instruction is fetched from RAM during the fetch stage (1).

No marks0/1

B The data at a memory address

Why: Near miss: data is not fetched during the fetch stage; data is used during the execute stage.

No marks0/1

C The decoded instruction

Why: Misconception: an instruction is decoded after it is fetched, in the decode stage.

2Short recall2 marksSecondary Memory Swap Remove

A computer uses secondary storage to keep programs and data.

Give two examples of secondary storage devices that store data using magnetic media.

[2 marks]
Mark scheme

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

  • Hard disk drive/HDD (1)
  • External/portable hard disk drive (1)
  • Magnetic tape drive (1)
  • Magnetic tape (1)

Allow a named device or the storage media type, e.g. hard disk/hard disc for hard disk drive, tape for magnetic tape

Allow floppy disk/floppy disk drive

Do not accept solid state devices (SSD, USB flash drive/memory stick, SD card/memory card) or optical media (CD/DVD/Blu-ray) as these do not store data using magnetism

Example answers and how they were marked
Full marks2/2

Hard disk drive and magnetic tape

Why: Hard disk drive (1) and magnetic tape (1) are both magnetic secondary storage, so both marks are awarded.

Some marks1/2

Hard disk drive and SD card

Why: Hard disk drive is magnetic (1); an SD card is solid state, not magnetic, so the second mark is not awarded.

No marks0/2

CD and DVD

Why: Both are optical media, which the mark scheme says not to accept, so no marks are awarded.

3Explain2 marksPrimary Memory Swap Remove

RAM is used to store data while a computer is running.

Explain one reason why the data in RAM is lost when a computer is switched off.

[2 marks]
Mark scheme

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

  • RAM is volatile (memory) (1) because it needs a constant/continuous power supply to hold/store the data it contains (1)
  • Data is held in RAM as electrical states/charges (1) so when the power supply is removed these states cannot be kept/refreshed and the data is lost (1)
  • RAM is used as short-term storage for the data and instructions currently in use (1) because it can only hold them while the computer has power (1)

For both marks, the expansion must follow/associate with the statement and must link the loss of the data to the power supply being removed.

Accept 'RAM is volatile' on its own for the first mark; the second mark is only awarded for a linked reason about the power supply.

Do not accept 'RAM is temporary/short-term memory' or 'RAM is cleared when the computer is switched off' on its own for both marks, as neither gives a reason.

Do not accept answers that say the data is deleted/cleared/erased by the computer or the operating system, or that the data is saved/moved to secondary storage, without saying why the data cannot be kept (e.g. because RAM needs power/is volatile).

Example answers and how they were marked
Full marks2/2

RAM is volatile memory, which means it needs a constant power supply to keep the data it is holding. When the power is switched off, the data is lost.

Why: Linked point (1) for 'RAM is volatile memory' and reason (1) for needing a constant power supply to hold the data.

Some marks1/2

The data in RAM is lost because RAM is volatile memory.

Why: Point (1) for 'RAM is volatile' but no linked reason about the power supply, and the mark scheme states that 'RAM is volatile' alone earns only the first mark.

No marks0/2

The data is deleted from RAM by the operating system when the computer is shut down so that the memory is free for next time.

Why: No creditworthy point: the answer says the data is deleted without saying why it cannot be kept, which the mark scheme's 'Do not accept' line rules out.

4Explain2 marksFetch Decode Execute Cycle Swap Remove

The control unit is part of the CPU.

Explain the role of the control unit in the fetch-decode-execute cycle.

[2 marks]
Mark scheme

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

  • Decodes/interprets/translates the instruction (1) to work out what the instruction is/what operation is required (1)
  • Sends control signals to the other components (1) so that the correct component carries out the instruction (1), e.g. the ALU/main memory
  • Controls the fetch of the instruction from main memory (1) because the address of the next instruction is sent via the address bus (1)
  • Controls the fetch of the next instruction from main memory (1) by sending a control signal/read signal to main memory (1)

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

For the decode point, 'decodes the instruction' alone gains 1 mark; a second mark needs the purpose of decoding, i.e. working out what the instruction is/what operation is required.

Do not accept 'it controls the CPU' on its own, without naming a task in the cycle.

Do not accept 'it fetches the instruction from memory' on its own, as this describes the fetch step rather than the control unit's role; credit only if linked to controlling/signalling the fetch.

Do not accept carrying out arithmetic/logical operations, as these are carried out by the ALU, or holding the address of the next instruction, as this is the program counter.

Do not accept storing the instruction in a register (e.g. MAR/MDR), as this is not the role of the control unit.

Example answers and how they were marked
Full marks2/2

The control unit decodes each instruction, working out what it means, so that the CPU knows which component should carry it out.

Why: Linked point (1) and reason (1): decodes/interprets the instruction, and works out what it is/what operation is required.

Some marks1/2

It decodes the instruction that has been fetched from main memory.

Why: Decode point only (1); it does not explain the purpose of decoding, i.e. working out what the instruction is/what operation is required.

No marks0/2

It adds the two numbers together and stores the result in a register.

Why: Misconception: arithmetic is carried out by the ALU, which the mark scheme's Do not accept line covers.

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