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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 · 8 marks

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1Short 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.

2Describe2 marksEmbedded Systems Swap Remove

Many modern devices contain embedded systems.

Describe what is meant by the term embedded system.

[2 marks]
Mark scheme

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

  • It is a computer/processor built into a larger device (1) to carry out a single dedicated task/function (1)
  • It is a combination of a processor, memory and input/output in one unit (1) that controls the device it is part of (1)
  • It is a computer that forms part of another device (1) so it is not used as a general purpose computer (1)

Allow 'forms part of another device' or 'inside another device' for the first mark.

Do not award the second mark for a separate fact that is not linked to the first point, e.g. 'It is built into a device and it uses little power' would earn only the first mark (1).

Do not accept 'a small computer' on its own, with no reference to being part of another device or performing a dedicated task.

Do not accept 'a computer that controls a device' on its own, with no reference to it being built into/part of a larger device or carrying out a dedicated task.

Do not accept 'it performs a single dedicated task' on its own, with no reference to it being built into/part of a larger device.

Do not accept descriptions of a general purpose computer, e.g. 'it can run many different programs' or 'new software can be installed'.

Do not accept 'it is a system that is embedded in another system' as this repeats the term in the question.

Example answers and how they were marked
Full marks2/2

An embedded system is a computer built into a larger device to carry out one specific/dedicated task

Why: Linked point (1) that it is built into a larger device, developed (1) with the dedicated task it performs.

Some marks1/2

It is a small computer that is inside another device.

Why: First point only (1) - inside/part of another device - with no linked development of a dedicated task.

No marks0/2

It is a computer that controls a device.

Why: Near-miss: only says it controls a device, with no reference to being built into/part of a larger device or a dedicated task, so no marks.

3Explain2 marksFetch Decode Execute Cycle Swap Remove

The CPU carries out the fetch-decode-execute cycle.

Explain one reason why the address bus is used in the fetch stage of the fetch-decode-execute cycle.

[2 marks]
Mark scheme

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

  • The address bus carries the address of the next instruction (1) so the CPU can locate/fetch it from main memory/RAM (1)
  • The address bus carries the address of the memory location to be read (1) so the instruction/data stored there can be located/accessed (1)
  • The CPU needs to know where the next instruction is stored (1) so the address bus sends the address to main memory/RAM (1)

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

Allow 'from the program counter/PC' as part of the point for one mark, e.g. the address bus carries the address from the program counter (1), but the second mark needs the destination or purpose (e.g. to locate/fetch the instruction in main memory/RAM).

Do not award the second mark for naming the program counter/PC alone.

Do not accept answers that say the address bus carries data/instructions from main memory to the CPU, as these travel on the data bus.

Do not accept answers that say the address bus stores the address.

Do not allow an answer that only restates that the address bus carries addresses without saying which address or why it is needed.

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 that the CPU can locate the instruction that is to be fetched.

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

Some marks1/2

The address bus carries the address of the next instruction from the program counter.

Why: Point only (1); the second mark is not awarded because the destination/purpose of locating or fetching the instruction is missing.

No marks0/2

It carries the instruction from main memory back to the CPU so that it can be decoded.

Why: Misconception: instructions travel on the data bus, which the mark scheme's Do not accept line covers.

4Explain2 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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