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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 · 7 marks

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1Convert2 marksHexadecimal to Binary Conversion Swap Remove

Binary, denary and hexadecimal patterns represent numbers.

Convert the hexadecimal number 82 to 8-bit binary.

[2 marks]
Mark scheme

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

  • 1000 (1)
  • 0010 (1)

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

Example answers and how they were marked
Full marks2/2

1000 0010

Why: Each digit is 4 bits: 8 = 1000, 2 = 0010 (2).

Some marks1/2

1000 0011

Why: Converts 2 as if it were the next digit up. The first nibble is correct (1); the second is not.

No marks0/2

0010 1000

Why: The nibbles are in the wrong order. Neither nibble is correct.

2Calculate3 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
11000001
01100011
Mark scheme

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

  • 0010 (1)
  • 0100 (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

0010 0100

Why: 193 + 99 = 292, which needs 9 bits; the 8 bits that are kept are both correct (2).

Some marks1/2

0010 0101

Why: A slip in the last bit. The first nibble is correct (1); the second is not.

No marks0/2

1110 0011

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.

3Calculate2 marksBinary Shifts Swap Remove

Computer systems manipulate bit patterns.

Complete the table with the result of applying the shift to the binary pattern.

[2 marks]
Binary patternShift8-bit binary result
1100 0001Arithmetic shift right by 2
Mark scheme

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

  • 1111 (1)
  • 0000 (1)

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

Example answers and how they were marked
Full marks2/2

1111 0000

Why: Every bit moves 2 places right, with copies of the sign bit (1) in from the left: both nibbles are correct (2).

Some marks1/2

0011 0000

Why: Fills the gap on the left with 0s, as a logical shift would, instead of copying the sign bit. The second nibble is correct (1); the first is not.

No marks0/2

0000 0100

Why: Shifts the bits the wrong way. Neither nibble is correct.

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