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Edexcel GCSE Computer Science (1CP2) Exam Questions

Build a practice paper from 631 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 · 7 marks

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1Multiple choice1 markTranslators Swap Remove

A program contains a syntax error. An interpreter reports the error as soon as it finds it.

Identify when a compiler reports the syntax errors it finds in the source code.

[1 mark]
  • AAfter each line is translated
  • BAt the end of translating the program
  • CWhen the first error is found
  • DWhen the object code is run
Mark scheme
  • B At the end of translating the program (1)
  • The only correct answer is B. The correct answer is at the end of translating the program.
  • A is not correct because a compiler translates the whole program and does not report an error after each line; reporting after each line is how an interpreter behaves
  • C is not correct because a compiler does not stop at the first error; it finishes translating and reports the errors it finds at the end
  • D is not correct because syntax errors are found during translation, before the object code is run
Example answers and how they were marked
Full marks1/1

B At the end of translating the program

Why: Chosen option states that errors are reported once the whole program has been translated, as a compiler does (1).

No marks0/1

A After each line is translated

Why: Near miss: reporting an error after each line is the behaviour of an interpreter, not a compiler, so no mark.

No marks0/1

C When the first error is found

Why: Misconception that a compiler stops and reports at the first error it finds; a compiler reports the errors at the end of translation, so no mark.

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 (1) without being changed (1).

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.

3Describe2 marksTranslators Swap Remove

A high-level program must be translated into machine code before it can be run.

Describe how a compiler and an interpreter differ in when the translated code is executed.

[2 marks]
Mark scheme

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

  • The interpreter executes each line as soon as it has been translated (1) so translation and execution happen together/at the same time (1)
  • The compiler translates the whole program first (1) and the machine code is run later/separately (1)
  • The interpreter translates the code and runs it while the program is running (1) whereas the compiler does not run the code it produces (1)
  • The compiler produces translated code that is executed only after all the translation has finished (1) but the interpreter executes each line immediately (1)

Allow 'translates one line at a time' where it is linked to executing each line immediately.

Do not accept answers that only state that a compiler is faster/an interpreter is slower, without reference to when execution happens.

Do not accept answers that only give object code, error reporting or portability, without reference to when execution happens.

Do not accept the compiler executing the program as it translates it.

Example answers and how they were marked
Full marks2/2

The compiler translates the code first and the program is executed afterwards, but the interpreter executes each line as soon as it has been translated.

Why: Compiler translates the whole program first and it is executed afterwards (1) and interpreter executes each line as soon as it is translated (1).

Some marks1/2

The interpreter executes each line immediately after translating it.

Why: Correct interpreter timing (1); no comparison with when the compiler's translated code is executed.

No marks0/2

The compiler executes the program line by line as it translates it.

Why: Reverses the two translators; a compiler does not execute the program it translates, so no mark.

4Explain2 marksTranslators Swap Remove

An interpreter translates and executes high-level code.

Explain why an interpreted program must be translated again each time it is run.

[2 marks]
Mark scheme

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

  • No object code/machine code file is stored/saved (1) so there is no translated program to run on the next occasion (1)
  • The translation is only temporary/is lost when the program ends (1) because each line is translated as the program runs (1)
  • No executable file is created/saved (1) so the whole program has to be translated again every time it is run (1)
  • The interpreter translates each line while the program is running (1) so nothing is kept that could be run without the interpreter (1)

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

Do not accept 'it is interpreted' or 'it is not compiled' without saying that no object code/executable is stored/saved.

Do not accept 'the source code is high-level so it must be translated' or 'the source code has to be turned into machine code' on its own, as this is true of any translation.

Do not accept answers about the source code being deleted.

Example answers and how they were marked
Full marks2/2

The interpreter does not store an object code file, so there is no machine code file to run on the next occasion.

Why: No object code stored (1) linked to no translated program for the next run (1).

Some marks1/2

No object code is saved.

Why: Point that nothing is stored (1) but no linked reason saying why this means the program must be translated again.

No marks0/2

It has to be translated again because the interpreter deletes the source code after each run.

Why: Incorrect: the interpreter does not delete the source code; no mark scheme point.

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