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Edexcel GCSE Computer Science (1CP2) Exam Questions

Build a practice paper from 659 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 marksTranslators Swap Remove

An interpreter is a type of translator.

Define the term interpreter.

[2 marks]
Mark scheme

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

  • Translates/converts (high-level/source) code one line/statement at a time (1)
  • Translates/converts the code and executes/runs each line as it goes (1)
  • Executes/runs each line/statement immediately after it is translated (1)
  • Reports/stops with an error message as soon as a syntax error is found (1)

Allow 'runs' for executes, 'converts' for translates and 'instruction' for line/statement

Do not accept translates the whole program before it is run

Do not accept produces/creates object code, an executable file or machine code that is saved

Example answers and how they were marked
Full marks2/2

An interpreter is a program that translates high-level code line by line. Each line is run as soon as it has been translated, so any errors are shown straight away.

Why: Line-by-line translation (1) and each line executed immediately (1); the point about errors would be a third creditworthy point but the maximum is two.

Some marks1/2

An interpreter translates code one line at a time.

Why: Line-by-line translation (1); no point for immediate execution.

No marks0/2

An interpreter translates the whole program before it is run.

Why: Near-miss describing a compiler; the scheme's 'Do not accept' line rules out whole-program translation.

2Short recall2 marksLow and High Level Languages Swap Remove

Programs written in a high-level language are often machine independent.

Define the term machine independence.

[2 marks]
Mark scheme

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

  • The (same) program/source code can run on different types/makes of computer/processor (1)
  • With few/no changes (to the program code) (1)
  • The same source code can be translated for each type of processor (1)
  • A different compiler/interpreter is used for each type of processor (1)
  • The program does not depend on one specific type of processor/hardware (1)
  • Only one version of the program needs to be written/kept (1)
  • The program is portable between different computers (1)

Allow 'different computers' as meaning different types of computer/processor.

Do not accept a program that will only run on one type of computer / the computer it was written on.

Do not accept written in machine code/binary, is translated into machine code, compiled/interpreted, is a low-level language.

Example answers and how they were marked
Full marks2/2

The same program can run on different types of computer without being changed.

Why: Two creditworthy parts: runs on different types/makes of computer/processor (1); with few/no changes (1).

Some marks1/2

A program can run on different computers.

Why: Creditworthy point: can run on different types/makes of computer/processor (1), with 'different computers' allowed by the guidance. No second part about changes or translation.

No marks0/2

A program is written in machine code so the computer can understand it.

Why: Misconception: machine code is not machine independence; the mark scheme does not accept this, and no other creditworthy point is given.

3Explain2 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.

4Explain2 marksTranslators Swap Remove

An interpreter translates a program one line at a time.

Explain why an interpreted program stops when it reaches a line that contains a syntax error.

[2 marks]
Mark scheme

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

  • The interpreter translates and executes each line in turn (1) so it cannot continue past a line it cannot translate (1)
  • The interpreter finds the error when it reaches that line (1) so it stops and displays an error message before later lines are executed (1)
  • Each line is translated just before it is executed (1) so a syntax error in that line prevents that translation/execution from happening (1)
  • The interpreter does not translate the whole program first (1) so it only discovers the error when that line is reached during execution (1)

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

Do not accept 'the program crashes' without saying that the interpreter cannot translate/execute the line.

Do not accept answers about how a compiler reports errors.

Example answers and how they were marked
Full marks2/2

The interpreter translates each line just before it executes it, so when it reaches the line with the syntax error it cannot translate that line and stops.

Why: Line-by-line translation (1) linked to being unable to translate the faulty line, so stopping (1).

Some marks1/2

The interpreter translates one line at a time, so it stops at the error.

Why: Line-by-line translation (1); 'stops at the error' repeats the outcome and does not explain why it cannot continue.

No marks0/2

It stops because the compiler reports all errors at the end.

Why: Describes a compiler, not an interpreter; no credit.

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