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Edexcel GCSE Computer Science (1CP2) Exam Questions

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4 questions · 7 marks

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1Multiple choice1 markStored Program Computers Swap Remove

Identify the function of the control unit in the fetch-decode-execute cycle.

[1 mark]
  • ADecodes instructions
  • BPerforms arithmetic operations
  • CStores data and instructions
  • DTemporarily stores data being processed
Mark scheme
  • A Decodes instructions (1)
  • The only correct answer is A. The correct answer is Decodes instructions.
  • B is not correct because the arithmetic logic unit performs arithmetic operations
  • C is not correct because main memory stores data and instructions
  • D is not correct because registers temporarily store data being processed
Example answers and how they were marked
Full marks1/1

A Decodes instructions

Why: Correct option: the control unit decodes instructions during the fetch-decode-execute cycle (1).

No marks0/1

C Stores data and instructions

Why: Main memory stores data and instructions, not the control unit; this is a common distractor, so no mark.

No marks0/1

B Performs arithmetic operations

Why: Arithmetic operations are performed by the ALU, not the control unit; a common confusion between CPU components, so no mark.

2Short recall2 marksFetch Decode Execute Cycle Swap Remove

The control unit is one component of the CPU.

Give two roles of the control unit during the fetch-decode-execute cycle.

[2 marks]
Mark scheme

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

  • Decodes the instruction / works out what the instruction is (1)
  • Sends control signals to the other components (of the CPU) (1)
  • Coordinates/controls the activities of the CPU (1)
  • Directs the timing of the other components / controls when each component acts (1)

Do not accept carrying out arithmetic or logical operations, as this is the role of the ALU.

Do not accept holding/storing the data or instructions, as this is the role of the registers/main memory.

Example answers and how they were marked
Full marks2/2

It decodes each instruction and sends control signals to the other components to tell them what to do.

Why: Decodes the instruction (1) and sends control signals to the other components (1).

Some marks1/2

It decodes the instructions and carries out the calculations.

Why: Decoding the instruction (1); the calculations are carried out by the ALU, so the second part earns nothing.

No marks0/2

It stores the data that the CPU is working on.

Why: Storing data is the role of the registers/main memory, not the control unit, so no point is creditworthy.

3Describe2 marksTranslators Swap Remove

A compiler and an interpreter both translate source code.

Describe one difference between what a compiler produces and what an interpreter produces.

[2 marks]
Mark scheme

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

  • A compiler produces object code/machine code/an executable (file) (1) whereas an interpreter produces no object code/translated file (1)
  • A compiler produces a machine code file (1) that can be run on its own/without the compiler/translator being present (1)
  • An interpreter produces no object code/file (1) because it translates and executes each line instead of saving translated code (1)
  • The compiler's output can be saved/stored (1) and run again later, while interpreted code has to be translated again each time it is run (1)

Allow binary for machine code.

Allow executable/an executable for object code.

Do not accept responses about translating the whole program, reporting errors or the speed of execution.

Do not accept 'the interpreter translates/executes one line at a time' on its own: this is how it translates, not what it produces. It earns the development only when linked to no object code/translated file being produced.

Do not accept the interpreter producing object code/an executable.

Example answers and how they were marked
Full marks2/2

A compiler produces object code, which is saved as a file, whereas an interpreter does not produce a file because it translates and executes each line.

Why: Compiler produces object code (1) contrasted with the interpreter producing no object code/translated file (1).

Some marks1/2

The compiler produces machine code.

Why: Machine code/object code produced (1); there is no contrast with the interpreter, so the development is not earned.

No marks0/2

The interpreter produces object code for each line it translates.

Why: Reverses the translators' outputs: the interpreter produces no object code, so nothing is creditworthy.

4Calculate2 marksBinary Shifts Swap Remove

Computers manipulate binary patterns.

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

[2 marks]
Binary patternShift8-bit binary result
1000 0001Logical shift right by 1
Mark scheme

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

  • 0100 (1)
  • 0000 (1)

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

Example answers and how they were marked
Full marks2/2

0100 0000

Why: Every bit moves 1 place right, with 0s in from the left: both nibbles are correct (2).

Some marks1/2

0100 0001

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

No marks0/2

0000 0010

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

Questions by topic

2.1 Binary

Build a paper on this topic 58
Adding Binary Numbers 6 questions Binary and Hexadecimal Basics 10 questions Binary Shifts 6 questions Binary to Denary Conversion 6 questions Binary to Hexadecimal Conversion 6 questions Denary to Binary Conversion 6 questions Denary to Hexadecimal Conversion 6 questions Denary to Negative Binary Conversion 6 questions Hexadecimal to Binary Conversion 6 questions

2.2 Data representation

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Character Sets 18 questions Images 19 questions Sound 19 questions

2.3 Data storage and compression

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Compression 18 questions Units & Conversion 6 questions

3.1 Hardware

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Embedded Systems 17 questions Fetch Decode Execute Cycle 15 questions Primary Memory 15 questions Secondary Memory 15 questions Stored Program Computers 15 questions

3.2 Software

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File Management 18 questions Memory Management 16 questions Peripheral Management 11 questions Process Management 12 questions Purpose & Function of Operating Systems 17 questions Software Basics 13 questions User Management 18 questions Utility Software 19 questions

3.3 Programming languages

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Low and High Level Languages 19 questions Translators 18 questions

4.1 Networks

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Addressing 16 questions LANs & WANs 16 questions Network Speed 5 questions Packet Switching 16 questions Protocols & Layers 17 questions The Internet 16 questions Topologies 17 questions Wired Connections 17 questions Wireless Connections 18 questions

4.2 Network security

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Network Security Risks 18 questions Preventing Network Security Risks 18 questions

5.1 Environmental

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E-waste 17 questions Manufacturing Technology 19 questions

5.2 Ethical and legal

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Data Protection Act 14 questions Impact of AI 4 questions

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