Menu

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.

Build a paper

Topics (none ticked: all of them)
Question types (none ticked: all of them)

Practice paper

3 questions · 6 marks

Pick again
Print
1Convert2 marksDenary to Negative Binary Conversion Swap Remove

Computer systems manipulate bit patterns.

Convert the denary number -75 to 8-bit binary using two's complement.

[2 marks]
Mark scheme

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

  • 1011 (1)
  • 0101 (1)

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

Example answers and how they were marked
Full marks2/2

1011 0101

Why: 75 is 01001011; flip the bits (10110100) and add 1: both nibbles are correct (2).

Some marks1/2

1011 0100

Why: Flips the bits of 75 but doesn't add 1. The first nibble is correct (1); the second is not.

No marks0/2

1100 1011

Why: Uses sign and magnitude (a 1 in front of 75) instead of two's complement. Neither nibble is correct.

2Convert1 markDenary to Hexadecimal Conversion Swap Remove

Computer systems manipulate bit patterns.

Convert the hexadecimal number 8F to denary.

[1 mark]
Mark scheme

Award one mark for:

  • 143 (1)
Example answers and how they were marked
Full marks1/1

143

Why: 8 × 16 + 15 = 143 (1).

No marks0/1

248

Why: Takes the right-hand digit as the 16s, so the value is wrong.

No marks0/1

23

Why: Adds the two digits instead of multiplying the first by 16.

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
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.

Questions by topic

More ways to revise Edexcel GCSE Computer Science (1CP2)

Teachers: build a paper, print it with the mark schemes at the end, and sign your school up to set your classes activities on every topic.

Fetch Decode Explain isn't affiliated with or endorsed by Pearson Edexcel.