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Edexcel GCSE Computer Science (1CP2) Exam Questions

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1Multiple choice1 markTranslators Swap Remove

A compiler translates source code into machine code.

Identify why a compiled program can be run on a computer that does not have the compiler installed.

[1 mark]
  • AThe code is translated again each time it is run
  • BThe code is translated one line at a time
  • CThe object code is saved as a separate file
  • DThe source code is saved with the program
Mark scheme
  • C The object code is saved as a separate file (1)
  • The only correct answer is C. The correct answer is the object code is saved as a separate file.
  • A is not correct because a compiled program is not translated again when it is run
  • B is not correct because translating one line at a time is how an interpreter works
  • D is not correct because the source code is not needed to run a compiled program
Example answers and how they were marked
Full marks1/1

C The object code is saved as a separate file

Why: Selected the saved object code, which can be run without the compiler being present (1).

No marks0/1

D The source code is saved with the program

Why: Near miss: it is the object code, not the source code, that is saved and run on another computer.

No marks0/1

B The code is translated one line at a time

Why: Confuses a compiler with an interpreter: a compiled program is translated as a whole and is not translated again when it is run.

2Short 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.

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.

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