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Edexcel GCSE Computer Science (1CP2) Exam Questions

Build a practice paper from 604 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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1Short recall1 markUnits & Conversion Swap Remove

A file has a size of 2 kibibytes.

State the number of bytes in the file.

[1 mark]
Mark scheme

Award one mark for:

  • 2048 (1)
  • 2 × 1024 (1)
  • 2^11 (1)

Allow 2048 bytes.

Do not accept 2000, which is the number of bytes in two decimal kilobytes.

Do not accept 1024, which is the number of bytes in one kibibyte.

Do not accept 16, which is the number of bits in two bytes.

Example answers and how they were marked
Full marks1/1

2048

Why: 2048 is 2 × 1024, the number of bytes in 2 kibibytes (1).

No marks0/1

2000

Why: 2000 uses the decimal kilobyte, not the binary kibibyte; the mark scheme does not accept it.

No marks0/1

16

Why: 16 is the number of bits in two bytes, confusing bits with bytes; the mark scheme does not accept it.

2Describe2 marksLow and High Level Languages Swap Remove

A programmer writes a program in a high-level language.

Describe why the program can be run on computers with different processors.

[2 marks]
Mark scheme

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

  • The same source code can be run on different types/makes of processor (1) with few or no changes being made to the program (1)
  • A compiler/interpreter is available for each type of processor (1) to translate the source code into the machine code for that processor (1)
  • The statements are not tied to one processor's instruction set (1) so the program is portable between different computers (1)

Do not accept 'it is translated by a compiler' on its own.

Do not accept 'the program does not need to be translated' or 'it is easier to use'.

Example answers and how they were marked
Full marks2/2

A compiler exists for each type of processor (1) to translate the source code into the machine code for that processor (1).

Why: Names the translator for each processor (1) and links it to producing that processor's machine code (1).

Some marks1/2

The same program can be run on different computers.

Why: States that the same code runs on different machines (1) but does not develop it by saying that few or no changes are needed.

No marks0/2

Because it is translated by a compiler.

Why: A compiler on its own does not explain machine independence; the answer does not say that a translator exists for each type of processor.

3Calculate3 marksAdding Binary Numbers Swap Remove

Computers manipulate binary patterns.

(a)

Complete the table to show the 8-bit result of the binary addition.

[2 marks]
1286432168421
10111001
10111100
Mark scheme

Award one mark for each correct nibble in the correct order:

  • 0111 (1)
  • 0101 (1)

0 marks if the response is not 8-bit binary.

Ignore a carry shown beyond the eighth bit.

Example answers and how they were marked
Full marks2/2

0111 0101

Why: 185 + 188 = 373, which needs 9 bits; the 8 bits that are kept are both correct (2).

Some marks1/2

0000 0101

Why: Forgets to carry the 1s. The second nibble is correct (1); the first is not.

No marks0/2

1011 1101

Why: Never carries. Neither nibble is correct.

(b)

State the name of the error that occurs when this addition is carried out.

[1 mark]
Mark scheme

Award one mark for:

  • overflow (error) (1)
Example answers and how they were marked
Full marks1/1

Overflow

Why: The result needs more bits than are available (1).

No marks0/1

Underflow

Why: A near miss: the result is too big for 8 bits, not too small.

No marks0/1

A syntax error

Why: A syntax error is a mistake in a program's code, not in arithmetic.

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