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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

Device drivers allow hardware devices to work with a computer system.

Give two advantages of using a low-level programming language to write device drivers.

[2 marks]
Mark scheme

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

  • It can control/manipulate the hardware (components/registers/memory locations) directly (1)
  • Each instruction maps to a single machine-code instruction, so the behaviour/timing can be controlled precisely (1)
  • The code can run very quickly / has a fast execution time (1)
  • The code uses less memory/RAM (1)
  • The code can be optimised for a particular processor/chipset (1)

Only award one mark where both 'controls the hardware' and 'accesses registers/memory locations' are given, as these are the same point.

Do not accept 'it is closer to the hardware' without saying that it controls or accesses the hardware directly.

Do not accept easier/faster to write/program/learn/understand/debug (these are advantages of high-level languages).

Do not accept faster/quicker without qualification.

Do not accept portable/machine independent.

Do not accept does not need to be translated/compiled (assembly language must be assembled).

Do not accept it is a low-level language / a repeat of the question.

Example answers and how they were marked
Full marks2/2

It can control the hardware directly and the code runs very quickly.

Why: Two creditworthy advantages: controls the hardware directly (1); fast execution (1).

Some marks1/2

It uses less memory than a high-level language.

Why: Creditworthy point: uses less memory/RAM (1). Only one advantage given.

No marks0/2

It is easier to understand and debug than a high-level language.

Why: These are advantages of high-level languages, not low-level ones; the mark scheme does not accept easier to understand or debug.

3Explain2 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.

4Explain2 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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