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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 · 8 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.

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.

3Explain2 marksThe Internet Swap Remove

Every device that connects to the internet is given an IP address.

Explain one reason why every device on the internet needs a unique IP address.

[2 marks]
Mark scheme

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

  • Data/packets are delivered to the correct device (1) because the IP address identifies that device on the internet (1)
  • A reply is sent back to the device that made a request (1) because the sender's IP address is used as the destination address for the reply (1)
  • Routers can forward packets to the right device (1) because each packet's destination IP address matches only one device (1)
  • A device can be contacted by other devices (1) because other devices use its IP address to send data to it (1)

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

Allow 'so the router knows where to send data' only when expanded to say the IP address identifies the destination device / is used by routers to forward the packet to that device.

Do not accept 'so it can connect to the internet' / 'so it can access the internet' without saying how the address is used to identify the device or deliver data to it.

Do not accept 'so the device can be identified' on its own without saying what the identification is used for, e.g. delivering data or returning a reply.

Do not award a mark for restating that an IP address is unique / every device has a different address.

Example answers and how they were marked
Full marks2/2

So that data reaches the correct device. The IP address is how the internet tells one device apart from another, so packets are sent to that device and not to a different one.

Why: Point (1): data reaches the correct device. Reason (1): the IP address identifies/tells devices apart, so packets are sent to that device.

Some marks1/2

So that packets go to the right device, because every device has a different address.

Why: Point (1): packets go to the right device. The reason only restates that every device has a different address, which the mark scheme says does not earn the second mark.

No marks0/2

So it can connect to the internet.

Why: No linked explanation of how the address is used; 'so it can connect to the internet' is not accepted without expansion.

4Calculate3 marksAdding Binary Numbers Swap Remove

Binary patterns can represent numbers.

(a)

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

[2 marks]
1286432168421
11011011
11011100
Mark scheme

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

  • 1011 (1)
  • 0111 (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

1011 0111

Why: 219 + 220 = 439, which needs 9 bits; the 8 bits that are kept are both correct (2).

Some marks1/2

0000 0111

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

No marks0/2

1101 1111

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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