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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 · 6 marks

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1Multiple choice1 markFetch Decode Execute Cycle Swap Remove

Identify the component that stores instructions and data during the fetch-decode-execute cycle.

[1 mark]
  • AArithmetic logic unit
  • BClock
  • CMain memory (RAM)
  • DProgram counter
Mark scheme
  • C Main memory (RAM) (1)
  • The only correct answer is C. The correct answer is main memory (RAM); accept 'main memory', 'RAM' or 'random access memory'.
  • A is not correct because the arithmetic logic unit performs arithmetic and logical operations
  • B is not correct because the clock sends regular pulses to synchronise the components of the CPU
  • D is not correct because the program counter holds the address of the next instruction, not the instructions and data
Example answers and how they were marked
Full marks1/1

C Main memory (RAM)

Why: Correct option: main memory (RAM) stores instructions and data during the fetch-decode-execute cycle (1).

No marks0/1

D Program counter

Why: Near-miss distractor: the program counter holds the address of the next instruction, not the instructions and data (0).

No marks0/1

A Arithmetic logic unit

Why: Misconception: the ALU performs arithmetic and logical operations, so it does not store instructions and data (0).

2Multiple choice1 markFetch Decode Execute Cycle Swap Remove

Identify the bus that carries memory addresses from the CPU to main memory. (1)

[1 mark]
  • AAddress bus
  • BControl bus
  • CData bus
  • DProgram counter
Mark scheme
  • A Address bus (1)
  • The only correct answer is A. The correct answer is address bus.
  • B is not correct because the control bus carries control signals
  • C is not correct because the data bus carries data and instructions
  • D is not correct because the program counter holds the address of the next instruction, it does not carry addresses
Example answers and how they were marked
Full marks1/1

A Address bus

Why: Correct option: the address bus carries memory addresses from the CPU to main memory (1).

No marks0/1

C Data bus

Why: Near-miss distractor: the data bus carries data and instructions between the CPU and main memory, not memory addresses (0).

No marks0/1

D Program counter

Why: Misconception: the program counter is a register that holds the address of the next instruction, it does not carry addresses to main memory (0).

3Describe2 marksEmbedded Systems Swap Remove

A drone is controlled by an embedded system.

Describe the purpose of the embedded system in the drone.

[2 marks]
Mark scheme

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

  • It controls the motors/rotors (1) so that the drone can take off, hover, turn and land (1)
  • It keeps the drone stable/level automatically (1) by taking readings from a sensor (accelerometer/gyroscope/GPS) (1)
  • It receives signals from the remote control (1) and changes the speed of the motors to steer the drone (1)
  • It monitors the battery level (1) and brings the drone back to the ground before the battery runs out (1)

The development must relate to the function given in the point.

Accept a named function that the embedded system controls, e.g. 'it keeps the drone level', as the first mark (1).

Award the second mark only when the development gives a specific outcome or detail of that function, e.g. 'so that the drone can take off, hover, turn and land' or 'by changing the motor speeds to keep it level'.

Do not award the second mark for a generic outcome such as 'so it works', 'so it can fly' or 'so the drone moves'.

A bare 'it controls the motors so it can fly' therefore earns the first mark only.

Allow any other specific function of a drone that is carried out by the embedded system.

Do not accept 'it flies the drone' / 'it is the drone's brain' / 'it makes the drone work' without a named function being controlled.

Do not accept answers that describe the user or the remote control flying the drone with no function carried out by the embedded system.

Example answers and how they were marked
Full marks2/2

It keeps the drone level while it is in the air by reading the accelerometer and changing the speed of the motors.

Why: Named function of the embedded system, keeping the drone level (1), developed with the sensor reading and motor speed changes that achieve it (1).

Some marks1/2

It controls the motors of the drone.

Why: First mark only (1) for naming a function the embedded system controls, with no linked outcome or detail to earn the second mark.

No marks0/2

It is the brain of the drone and makes the drone work.

Why: Vague phrase with no named function being controlled, which the mark scheme's 'Do not accept' line rules out.

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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