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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 · 6 marks

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1Describe2 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.

2Explain2 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.

3Explain2 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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