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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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1Describe2 marksTranslators Swap Remove

Source code can contain syntax errors.

Describe how a compiler and an interpreter differ in the way they deal with syntax errors.

[2 marks]
Mark scheme

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

  • The compiler reports all syntax errors after translation has finished (1) whereas the interpreter stops at the first error it finds (1)
  • The interpreter reports a syntax error as soon as it finds one (1) and does not translate/execute any more of the program (1)
  • The compiler continues translating after an error (1) and reports the errors at the end (1)
  • The interpreter stops translating when it reaches an error (1) but the compiler finishes translating before reporting errors (1)

Do not accept answers about fixing/correcting errors or about object code.

Do not award 'the compiler finds more errors' without saying errors are reported at the end.

Example answers and how they were marked
Full marks2/2

A compiler reports all the syntax errors at the end of translation, whereas an interpreter stops and reports the error as soon as it finds one.

Why: Compiler reports errors at the end (1) and interpreter stops/reports at the first error (1).

Some marks1/2

An interpreter stops translating when it finds a syntax error.

Why: Interpreter stops at the first error (1); no comparison with when the compiler reports errors.

No marks0/2

A compiler reports a syntax error immediately, before translating the rest of the program.

Why: Reverses the compiler's behaviour; it finishes translating before reporting errors.

2Explain2 marksTranslators Swap Remove

A program can be translated by a compiler or by an interpreter.

Explain why a compiled program usually runs faster than an interpreted program.

[2 marks]
Mark scheme

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

  • The compiler translates the whole program into machine code before it is run (1) so no translation is needed while the program is executing (1)
  • The machine code/object code is already produced before execution (1) so the CPU can carry out the instructions directly without translating them (1)
  • The compiled program does not need an interpreter at run time (1) so no time is spent translating each line before it is executed (1)

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

A statement that translation happens before execution, with no linked reason for faster running, earns 1 mark only.

Do not accept 'faster to run' or 'quicker' on its own without a reason linked to translation before/during execution.

Do not accept 'compiled code is optimised' or 'compilation takes less time' without linking this to translation before execution/at run time.

Do not accept answers about the compiler being installed or available.

The question asks why a compiled program usually runs faster, so answers must refer to when translation happens, not just general performance claims.

Example answers and how they were marked
Full marks2/2

The compiler translates the whole program into machine code before it is run, so the CPU does not have to translate each line during execution.

Why: Translation before execution (1) linked to no translation needed during the run, so faster (1).

Some marks1/2

The compiler translates the whole program first.

Why: Pre-translation point (1) but no link to faster running.

No marks0/2

A compiled program runs faster because the compiler is installed on the computer.

Why: Compiler being installed does not make execution faster; no credit.

3Explain2 marksLow and High Level Languages Swap Remove

Device drivers are programs that allow the operating system to communicate with hardware.

Explain one reason why a device driver is often written in a low-level language.

[2 marks]
Mark scheme

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

  • The programmer can control/manipulate the hardware directly (1) because low-level instructions can access registers/memory addresses/hardware features (1)
  • The code can be made to work efficiently with a specific device (1) because low-level languages are processor/chipset specific, so the instructions match that hardware (1)
  • The code produced is fast to execute (1) because it is optimised for the specific processor/uses few instructions (1)
  • The code produced is small (1) so it fits in the limited memory/ROM available in the device (1)

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

Fast execution and small code size are typical advantages of low-level languages; award them only where the linked reason relates to the device.

Do not accept 'it is easier to write/learn/understand' or 'it is faster to write' as a point or as the expansion, because low-level languages are not easier for these.

Do not accept 'it is close to the hardware' or 'it works with hardware' without expansion of what that allows the program to do.

Do not accept 'because it is low-level' as the expansion; the answer must say what the language/hardware allows.

Example answers and how they were marked
Full marks2/2

It can control the hardware directly because the instructions can read and write to the device's registers and memory addresses.

Why: Linked point (1) of direct hardware control and reason (1) that low-level instructions access registers and memory addresses.

Some marks1/2

It runs quickly because it is a low-level language.

Why: Point (1) of fast execution, but 'because it is a low-level language' is not accepted as the linked reason.

No marks0/2

Because it is easier to write programs for a particular device.

Why: Misconception that low-level languages are easier to write; no creditworthy point or linked reason about hardware control or efficiency.

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