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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

A computer is running an application. The application's data and instructions are transferred from secondary storage into RAM before the CPU processes them.

Identify the reason for this transfer.

[1 mark]
  • ARAM is non-volatile
  • BRAM is faster to access than secondary storage
  • CRAM has a larger capacity than secondary storage
  • DRAM is cheaper than secondary storage
Mark scheme
  • B RAM is faster to access than secondary storage (1)
  • The only correct answer is B. The correct answer is RAM is faster to access than secondary storage.
  • A is not correct because RAM is volatile
  • C is not correct because RAM has a smaller capacity than secondary storage
  • D is not correct because RAM is more expensive than secondary storage
Example answers and how they were marked
Full marks1/1

B RAM is faster to access than secondary storage

Why: Selects the correct option: RAM is faster to access than secondary storage, so data and instructions can reach the CPU quickly (1).

No marks0/1

A RAM is non-volatile

Why: Near miss: RAM is volatile; this does not explain the transfer into RAM.

No marks0/1

C RAM has a larger capacity than secondary storage

Why: Misconception: assumes primary memory has a larger capacity, but RAM has a smaller capacity than secondary storage.

2Short recall2 marksStored Program Computers Swap Remove

The central processing unit (CPU) contains an arithmetic logic unit (ALU).

State two types of operation carried out by the ALU.

[2 marks]
Mark scheme

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

  • An arithmetic operation, e.g. addition/subtraction/multiplication/division (1)
  • A logical operation, e.g. comparing two values (is A > B?) / using AND, OR, NOT (1)

Do not accept decoding instructions, fetching instructions or controlling the timing of the CPU, as these are carried out by the control unit.

Example answers and how they were marked
Full marks2/2

It carries out arithmetic operations such as addition and subtraction, and logical operations such as comparing two values to see if one is greater than the other.

Why: Arithmetic operation (1) and logical operation (1).

Some marks1/2

It adds numbers together and works out the result.

Why: Arithmetic operation, addition (1). No logical operation.

No marks0/2

It decodes the instructions that have been fetched from main memory.

Why: Decoding and fetching are the control unit's role; the mark scheme's do-not-accept line covers this.

3Short recall2 marksStored Program Computers Swap Remove

Computers use the von Neumann stored program concept.

Define the term stored program concept.

[2 marks]
Mark scheme

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

  • Program instructions are stored in main memory/RAM (1)
  • The data used by the program is stored in main memory/RAM (1)
  • The CPU fetches/reads instructions from main memory to execute them (1)
  • The program can be run without the instructions being input again (1)

Allow 'the program is stored in memory' for one mark.

Do not accept answers about programs being stored on secondary storage, such as a hard disk or USB memory stick.

Do not accept answers that only describe the von Neumann architecture (e.g. having a CPU and memory) without stating that instructions are stored in main memory.

Example answers and how they were marked
Full marks2/2

Both the program instructions and the data the program uses are held in the same main memory, and the CPU fetches these instructions from memory to execute them.

Why: Instructions stored in main memory (1) and the CPU fetches instructions from memory to execute them (1).

Some marks1/2

Program instructions are stored in main memory.

Why: Instructions stored in main memory (1). No second point about data being stored in the same memory or about the CPU fetching instructions.

No marks0/2

The program is saved on the hard disk so that it can be loaded into RAM when the user runs it.

Why: A near-miss about secondary storage, which the mark scheme says not to accept; the stored program concept is about instructions being held in main memory.

4Describe2 marksStored Program Computers Swap Remove

The control unit (CU) is a component inside the CPU.

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

[2 marks]
Mark scheme

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

  • Decodes each (fetched) instruction (1) to work out which operation is needed / which components should carry it out (1)
  • Coordinates/directs the other components (1) by sending control signals along the control bus (1)
  • Fetches the next instruction (1) by sending its address to main memory along the address bus (1)
  • Sends a read/write control signal to main memory (1) so that the instruction or data is transferred during the fetch/execute stage (1)

Do not accept answers about synchronising the CPU or timing the cycles (that is the role of the clock).

Do not accept answers about carrying out arithmetic or logical operations (that is the ALU).

Do not accept answers about holding data or the results of instructions (that is registers/main memory).

Do not accept generic answers that only say the CU controls the CPU or processes instructions, with no linked development.

Only award one mark for a response that only repeats that the CU sends control signals; the second mark needs a linked outcome such as coordination, a memory read/write, or fetching an instruction.

Do not accept 'during the decode stage' as the development for the decoding point, as it restates the question.

Example answers and how they were marked
Full marks2/2

It decodes the instruction that has been fetched so that it knows which operation the CPU must carry out and which components should do it.

Why: Decoding named with the acceptable wording 'each (fetched) instruction' (1), plus the linked development that this identifies the operation and components (1).

Some marks1/2

It decodes each instruction during the decode stage of the cycle.

Why: Earns (1) for decoding the instruction. 'During the decode stage' restates the question and is not accepted as a development, so the second mark is not earned.

No marks0/2

It carries out the calculations and comparisons when the instruction is executed.

Why: Calculations and comparisons are the ALU's role, which the 'Do not accept' line rules out, so no mark is earned.

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