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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 · 6 marks

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1Short recall2 marksPrimary Memory Swap Remove

A computer is designed using 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:

  • The program instructions and data are stored together in main memory/RAM (1)
  • The same memory is used for both instructions and data (1)
  • The instructions are fetched from main memory and executed by the CPU (1)
  • The instructions are fetched and executed one at a time / in sequence (1)
  • The program can be changed/replaced by loading new instructions into memory, without changing the hardware (1)

Do not accept the program is stored in secondary storage / on the hard disk.

Do not accept the program is stored in the CPU / in registers.

Example answers and how they were marked
Full marks2/2

The program instructions and the data are stored together in main memory, and the CPU fetches the instructions one at a time and executes them.

Why: Creditworthy point that instructions and data are stored in the same main memory (1) and the linked point that the CPU fetches and executes them from memory (1).

Some marks1/2

The program is held in the main memory (RAM) so that the computer can run it.

Why: Earns the point that the program instructions are stored in main memory (1), but does not say that the CPU fetches and executes them, so the second mark is not earned.

No marks0/2

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

Why: Both parts are misconceptions named in the Do not accept lines: the stored program concept keeps the instructions in main memory, not on secondary storage or in the CPU.

2Describe2 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.

3Describe2 marksEmbedded Systems Swap Remove

A greenhouse uses an embedded system to control the growing conditions for plants.

Describe how the embedded system controls the growing conditions in the greenhouse.

[2 marks]
Mark scheme

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

  • It reads/monitors the temperature/humidity/light level using sensors (1) to switch the heaters/vents/lamps/watering system on or off when the reading is outside the set range (1)
  • It compares the readings from the sensors with the set values/thresholds stored in its memory (1) to decide whether the conditions need to be changed (1)
  • It monitors the light level using a light sensor (1) and turns the lamps on when the light falls below the level the plants need (1)
  • It monitors the soil moisture using a soil moisture sensor (1) and turns the water pump/irrigation on when the soil is too dry (1)

For the second mark, the action/response must be linked to the sensor reading given in the first point.

Allow named sensors (temperature/humidity/light/soil moisture) and named outputs (heater, fan, vent/window, lamp, irrigation/water pump).

Do not accept answers that only name a sensor or only name an output, e.g. 'it has a temperature sensor and a heater', as there is no link between the reading and the control action.

Do not accept answers where a person switches the equipment on or off, as the embedded system controls the conditions automatically.

Example answers and how they were marked
Full marks2/2

The embedded system reads the temperature using a sensor and switches the heater on when the temperature is below the set value.

Why: Sensor reading point (1) and linked control action (1).

Some marks1/2

The embedded system compares the readings from the sensors with the set values stored in its memory.

Why: First point only (1) - the comparison with stored values - with no linked action.

No marks0/2

The greenhouse has a temperature sensor and a heater.

Why: Only names a sensor and an output, which the mark scheme says is not accepted.

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