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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 · 5 marks

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1Short recall1 markTranslators Swap Remove

An interpreter translates high-level code.

State what happens to the translation of a program when an interpreter finds a syntax error.

[1 mark]
Mark scheme

Award one mark for any of the following:

  • Translation/execution stops (when the error is found) / the rest of the program is not translated/executed (1)

Allow stops/terminates/halts when the error is found

Do not accept shows/displays an error message on its own

Do not accept the whole program is translated and errors are reported at the end

Do not accept translates line by line on its own

Example answers and how they were marked
Full marks1/1

The translation stops as soon as the error is found, so the rest of the program is not translated.

Why: Translation stops when the error is found (1).

No marks0/1

An error message is displayed.

Why: Only an error message; it does not say translation stops, and the scheme does not accept a displayed error message on its own.

No marks0/1

The whole program is translated and all the errors are reported at the end.

Why: Describes a compiler; the scheme does not accept errors being reported at the end of translating the whole program.

2Describe2 marksLow and High Level Languages Swap Remove

A programmer has written a program in assembly language.

Describe why it is necessary to translate the program into machine code before it can be run.

[2 marks]
Mark scheme

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

  • The processor/CPU can only execute machine code/binary instructions (1) so the assembly instructions must be converted into machine code before the program can run (1)
  • Each assembly instruction/mnemonic matches/corresponds to one machine code instruction (1) so each line must be replaced with the machine code the processor executes (1)
  • The program is written using mnemonics (1) that must be translated into machine code for the processor to carry out the instructions (1)
  • The hardware/processor does not understand assembly language directly (1) so it must be translated into machine code that the processor can execute (1)

Do not accept 'assembly language is a low-level language'.

Do not accept 'it is hard to understand' or 'it is not English'.

Do not accept benefits, such as 'machine code runs faster' or 'the program will run more quickly'.

Do not accept 'an assembler/a translator converts it' on its own, with no reference to the processor only being able to execute machine code/binary.

Do not accept responses about high-level languages or about compilers/interpreters.

Example answers and how they were marked
Full marks2/2

The processor can only execute machine code, so the assembly instructions must be converted into machine code before the program can run.

Why: States what the processor can execute (1) and links it to converting the program's instructions into machine code (1).

Some marks1/2

Each assembly instruction matches one machine code instruction.

Why: Correct point about the one-to-one match (1) but no development saying that this is because the processor only executes machine code.

No marks0/2

Because an assembler translates assembly language into machine code.

Why: Names the translator but gives no reason tied to the processor only being able to execute machine code, so no mark; this is in the 'Do not accept' guidance.

3Explain2 marksTranslators Swap Remove

A programmer writes a program in a high-level language. The program is translated by a compiler.

Explain why a compiler must translate the whole program before any of it can be executed.

[2 marks]
Mark scheme

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

  • The compiler produces object code/machine code for the whole program (1) so there is no complete executable until every line has been translated (1)
  • The compiler translates all the source code before producing the object code (1) so the program cannot start until translation has finished (1)
  • The compiler checks the whole program for errors during translation (1) so all of the source code must be read before an executable can be produced (1)

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

Allow 'in one go'/'all at once' for the translation point, but this does not earn the second mark unless it is linked to why the program cannot be executed until translation has finished.

A statement that the whole program is translated, with no linked reason about when the program can be executed, earns 1 mark only.

Do not accept 'a compiler is faster' or 'compiled code runs faster' on its own; this does not explain why translation must finish before execution.

Do not accept 'it translates and runs the program one line at a time', as this describes an interpreter.

Example answers and how they were marked
Full marks2/2

A compiler produces object code for the whole program, so there is no complete executable until every line has been translated.

Why: Object code for the whole program (1) linked to there being no complete executable until every line is translated (1).

Some marks1/2

A compiler translates the whole program in one go.

Why: Translation of the whole program only (1); no linked reason about when the program can be executed, so the second mark is not awarded.

No marks0/2

A compiler translates and runs the program one line at a time, so it stops when it finds an error.

Why: Confuses a compiler with an interpreter; nothing about translating the whole program before execution, so no creditworthy point.

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