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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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4 questions · 6 marks

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1Multiple choice1 markStored Program Computers Swap Remove

Identify the bus that carries addresses in one direction only, from the CPU to main memory.

[1 mark]
  • AAddress bus
  • BControl bus
  • CData bus
  • DSystem bus
Mark scheme
  • A Address bus (1)
  • The only correct answer is A. The correct answer is address bus. Do not accept 'address' on its own.
  • B is not correct because the control bus carries control signals in both directions between the CPU and other components
  • C is not correct because the data bus carries data in both directions between the CPU and main memory
  • D is not correct because the system bus is the collection of all three buses
Example answers and how they were marked
Full marks1/1

A Address bus

Why: Correct option: the address bus carries addresses in one direction only, from the CPU to main memory (1).

No marks0/1

C Data bus

Why: The data bus carries data in both directions, so it is not the bus that carries addresses in one direction only from the CPU to main memory; no creditworthy point.

No marks0/1

B Control bus

Why: The control bus carries control signals in both directions, not addresses in one direction only; this is the common control/address bus confusion, so no mark.

2Multiple choice1 markCharacter Sets Swap Remove

ASCII is a character set used for representing text.

Identify the number of bits used to encode each character in ASCII.

[1 mark]
  • A6
  • B7
  • C8
  • D16
Mark scheme
  • B 7 (1)
  • The only correct answer is B. The correct answer is 7 bits.
  • A is not correct because 6 bits give only 64 different characters
  • C is not correct because 8 bits are used by extended ASCII to give 256 characters
  • D is not correct because 16 bits give 65 536 different characters, which is far more than the 128 in ASCII
Example answers and how they were marked
Full marks1/1

B 7

Why: B is the only correct answer: each ASCII character is encoded using 7 bits (1).

No marks0/1

C 8

Why: Near miss scoring 0: 8 bits is extended ASCII, and the scheme's C line says extended ASCII, not ASCII, is not the answer.

No marks0/1

A 6

Why: Misconception scoring 0: 6 bits give only 64 different characters, so it cannot be ASCII.

3Short recall2 marksStored Program Computers Swap Remove

The central processing unit (CPU) contains an arithmetic logic unit (ALU).

State two types of operation carried out by the ALU.

[2 marks]
Mark scheme

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

  • An arithmetic operation, e.g. addition/subtraction/multiplication/division (1)
  • A logical operation, e.g. comparing two values (is A > B?) / using AND, OR, NOT (1)

Do not accept decoding instructions, fetching instructions or controlling the timing of the CPU, as these are carried out by the control unit.

Example answers and how they were marked
Full marks2/2

It carries out arithmetic operations such as addition and subtraction, and logical operations such as comparing two values to see if one is greater than the other.

Why: Arithmetic operation (1) and logical operation (1).

Some marks1/2

It adds numbers together and works out the result.

Why: Arithmetic operation, addition (1). No logical operation.

No marks0/2

It decodes the instructions that have been fetched from main memory.

Why: Decoding and fetching are the control unit's role; the mark scheme's do-not-accept line covers this.

4Explain2 marksTopologies Swap Remove

A bus topology has a terminator at each end of its cable.

Explain why terminators are needed in a bus topology.

[2 marks]
Mark scheme

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

  • Terminators absorb the signal at the ends of the cable (1) so it is not reflected back along the bus (1)
  • Terminators prevent signals reflecting/bouncing back (1) so the reflected signal does not corrupt data on the cable (1)
  • Terminators absorb the signal (1) so it does not collide/interfere with data being sent by other devices (1)
  • Terminators stop the signal reflecting back down the cable (1) so data can be transmitted and received without errors (1)

For both marks, the expansion must follow/associate with the statement.

Allow 'interfere'/'corrupt' only where the answer says the reflected signal mixes with/collides with data on the cable.

Do not accept 'to stop the signal' on its own, as stopping the signal is not the same as stopping it reflecting back along the cable.

Do not accept 'to terminate the cable/network', 'to end the cable' or 'to stop the cable breaking'.

Do not award responses that only repeat the stem, e.g. 'because there is a terminator at each end'.

Example answers and how they were marked
Full marks2/2

Terminators absorb the signal at each end of the cable (1) so that it does not reflect back along the bus (1).

Why: Linked point (1) and reason (1): absorbing the signal is linked to it not being reflected back along the bus.

Some marks1/2

Terminators absorb the signal at the ends of the cable.

Why: Awarded 1 mark for the point that the signal is absorbed, but no linked consequence is given.

No marks0/2

They terminate the network so the cable does not break.

Why: No credit: it does not say the signal is absorbed or that reflections are prevented, and the mark scheme rejects 'to terminate the network' and 'to stop the cable breaking'.

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