Menu
Exam Questions

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 · 14 marks

Pick again
Print
1Describe2 marksStored Program Computers Swap Remove

The control unit (CU) is a component inside the CPU.

Describe the role of the control unit in the fetch-decode-execute cycle.

[2 marks]
Mark scheme

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

  • Decodes each (fetched) instruction (1) to work out which operation is needed / which components should carry it out (1)
  • Coordinates/directs the other components (1) by sending control signals along the control bus (1)
  • Fetches the next instruction (1) by sending its address to main memory along the address bus (1)
  • Sends a read/write control signal to main memory (1) so that the instruction or data is transferred during the fetch/execute stage (1)

Do not accept answers about synchronising the CPU or timing the cycles (that is the role of the clock).

Do not accept answers about carrying out arithmetic or logical operations (that is the ALU).

Do not accept answers about holding data or the results of instructions (that is registers/main memory).

Do not accept generic answers that only say the CU controls the CPU or processes instructions, with no linked development.

Only award one mark for a response that only repeats that the CU sends control signals; the second mark needs a linked outcome such as coordination, a memory read/write, or fetching an instruction.

Do not accept 'during the decode stage' as the development for the decoding point, as it restates the question.

Example answers and how they were marked
Full marks2/2

It decodes the instruction that has been fetched so that it knows which operation the CPU must carry out and which components should do it.

Why: Decoding named with the acceptable wording 'each (fetched) instruction' (1), plus the linked development that this identifies the operation and components (1).

Some marks1/2

It decodes each instruction during the decode stage of the cycle.

Why: Earns (1) for decoding the instruction. 'During the decode stage' restates the question and is not accepted as a development, so the second mark is not earned.

No marks0/2

It carries out the calculations and comparisons when the instruction is executed.

Why: Calculations and comparisons are the ALU's role, which the 'Do not accept' line rules out, so no mark is earned.

2Discuss6 marksPrimary Memory Swap Remove

A video production company edits films for its clients. The editors use computers to work on 4K video, and they say the computers have become slow. One editor wants to replace the CPU, but a colleague thinks adding more RAM would be better.

Discuss whether adding more RAM will improve the performance of the computers used to edit 4K video. (6)

Your answer should include:

  • how RAM is used when editing video
  • why too little RAM causes poor performance
  • why adding more RAM may not always improve performance.
[6 marks]
Mark scheme

Indicative content

How RAM is used when editing video

  • The editing software and the video project being worked on are loaded into RAM so that the CPU can access them quickly.
  • RAM holds the frames, effects and timeline data that the CPU is processing as part of the fetch-decode-execute cycle.
  • The CPU fetches the instructions and the video data it needs from RAM, which is much faster than fetching them from secondary storage.
  • Having more RAM means that more of the 4K video project and its effects can be held in memory at the same time.
  • RAM is also used by the operating system and any other open software, so not all of the RAM is available to the editing software.

Why too little RAM causes poor performance

  • If there is not enough RAM, the operating system uses virtual memory on secondary storage for data that will not fit in RAM.
  • Virtual memory is much slower than RAM, so the editor waits longer for 4K video to load and for effects to be applied.
  • Data has to be swapped between RAM and virtual memory, which is extra work that slows the computer down.
  • The editing software may freeze or close if it runs out of memory while working on the 4K video.
  • Playback of the 4K video is not smooth because the frames cannot all be held in RAM ready for the CPU.

Why adding more RAM may not always improve performance

  • If the computer already has enough RAM for the editing software, the extra RAM will not be used and performance will hardly change.
  • The clock speed and the number of cores of the CPU decide how quickly instructions are processed, so a slow CPU will still limit how quickly the video is edited.
  • A slow secondary storage drive will still limit how quickly the 4K video files can be loaded into RAM.
  • Adding RAM only improves performance if a shortage of RAM was the reason for the computer being slow.

Levels

  • Level 0 (0 marks): No rewardable content.
  • Level 1 (1–2 marks): Basic, independent points are made, showing elements of understanding of key concepts/principles of computer science. (AO1) The discussion will contain basic information with little linkage between points made or application to the context. (AO2)
  • Level 2 (3–4 marks): Demonstrates adequate understanding of key concepts/principles of computer science. (AO1) The discussion shows some linkages and lines of reasoning with some structure and application to the context. (AO2)
  • Level 3 (5–6 marks): Demonstrates comprehensive understanding of key concepts/principles of computer science to support the discussion being presented. (AO1) The discussion is well developed, with sustained lines of reasoning that are coherent and logically structured, and which clearly apply to the context. (AO2)

Additional guidance

  • Level 3 responses must explain how RAM is used when editing video and give a developed reason why adding more RAM may not always improve performance; responses that only explain how RAM is used, or only why too little RAM causes poor performance, are limited to Level 2.
  • Accept 'paging' or 'swap file' as equivalent to virtual memory, but do not accept 'cache' or 'ROM'; do not credit statements that adding RAM increases the CPU clock speed or makes the CPU faster, or that 'RAM is volatile' explains poor performance, as these are not linked to the question asked.
Example answers and how they were marked
Full marks6/6

RAM holds the editing software and the 4K video project that is being worked on, so the CPU can fetch the frames and the effects it needs much faster than from the hard drive. If there is not enough RAM, the operating system has to use virtual memory on secondary storage instead, and this is much slower than RAM, so the editors have to wait for video to load and the playback is not smooth. Adding more RAM can help because more of the 4K project and its effects can be held in memory at once. However, it will not always improve performance. If the computer already has enough RAM the extra memory will not be used, and if the CPU has a low clock speed or too few cores it will still take longer to process each frame. A slow hard drive will also limit how quickly the 4K files can be loaded into RAM, so adding RAM only solves the problem if the computer was short of memory.

Why: Level 3: explains how RAM is used when editing video and applies it to the frames and effects (AO1/AO2), gives a developed reason for poor performance using virtual memory and its slowness, and gives developed reasons why extra RAM may not help, namely a CPU bottleneck (clock speed and cores) and a slow drive, applied to the company's 4K editing.

Some marks2/6

RAM is used to store the video while it is being edited. If you don't have enough RAM, the computer will be slow because it has to use the hard drive instead. Adding more RAM will make the computer faster because it can store more video. The CPU also matters because it does the processing.

Why: Level 1, top end (2 marks). A basic relevant use of RAM, storing the video being edited, and a basic point that the hard drive is used when RAM is short; the extra RAM point is asserted with no reasoning and the single CPU statement is not linked to why adding RAM may not help, so there is little development and the answer does not reach Level 2.

No marks0/6

RAM is the same as the CPU, so adding more RAM makes the CPU faster. The video editor should add more RAM to increase the clock speed. 4K video is slow because RAM is volatile.

Why: No creditworthy content: treating RAM as the CPU and saying adding RAM increases the clock speed are the misconceptions named in the guidance, and 'RAM is volatile' is not linked to performance, so it earns nothing.

3Discuss6 marksFetch Decode Execute Cycle Swap Remove

A small robotics company is designing a new robot. The robot's computer uses von Neumann architecture. The engineers are explaining how programs are stored and run.

Discuss how the von Neumann stored program concept and main memory (RAM) are used during the fetch-decode-execute cycle.

Your answer should include:

  • what is meant by the stored program concept
  • the role of RAM in the cycle
  • why the stored program concept is useful.
[6 marks]
Mark scheme

Indicative content

Stored program concept

  • Instructions and data are stored together in the same main memory (RAM).
  • Instructions are fetched one at a time from memory and executed in sequence.
  • The program can be changed by loading different instructions into RAM.
  • The CPU can only execute instructions that are in main memory.

Role of RAM

  • RAM holds the program instructions and the data being used.
  • The address of the next instruction is held in the program counter (PC).
  • The instruction is fetched from RAM using the address bus.
  • The data bus carries the instruction from RAM to the CPU.
  • RAM is volatile, so programs are lost when power is off.
  • RAM is directly accessible by the CPU, unlike secondary storage.

Benefits

  • The same hardware can run many different programs.
  • Programs can be loaded and changed quickly.
  • No need to rewire the computer for a new task.
  • Makes general-purpose computers possible.

Levels

  • Level 0 (0 marks): No rewardable content.
  • Level 1 (1–2 marks): Basic, independent points are made, showing elements of understanding of key concepts/principles of computer science. (AO1) The discussion will contain basic information with little linkage between points made or application to the context. (AO2)
  • Level 2 (3–4 marks): Demonstrates adequate understanding of key concepts/principles of computer science. (AO1) The discussion shows some linkages and lines of reasoning with some structure and application to the context. (AO2)
  • Level 3 (5–6 marks): Demonstrates comprehensive understanding of key concepts/principles of computer science to support the discussion being presented. (AO1) The discussion is well developed, with sustained lines of reasoning that are coherent and logically structured, and which clearly apply to the context. (AO2)
Example answers and how they were marked
Full marks6/6

The von Neumann stored program concept means that both the program instructions and the data are stored together in the same main memory, RAM. During the fetch-decode-execute cycle, the CPU fetches an instruction from RAM, decodes it in the control unit, and then executes it. The program counter holds the address of the next instruction, and this address is sent along the address bus to RAM. RAM then returns the instruction along the data bus to the CPU. RAM is volatile, so it only holds the program while the robot is powered on. The stored program concept is useful because the robot's computer can run different programs without changing any hardware; new instructions can simply be loaded into RAM. This makes the computer general-purpose and flexible.

Why: Comprehensive understanding: defines stored program concept, explains RAM role with PC, address bus and data bus, applies to robot, and gives benefits. Sustained lines of reasoning. Level 3.

Some marks3/6

The stored program concept is when instructions and data are stored in RAM. The CPU fetches instructions from RAM. The program counter keeps the address of the next instruction. RAM holds the program. The benefit is that you can change the program without rewiring the computer.

Why: Adequate understanding: correct basic points about stored program concept and RAM, with some linkage, but little development or application to the robot's fetch-decode-execute cycle. Level 2.

Some marks1/6

The von Neumann stored program concept is that the CPU uses RAM to store the program. The fetch-decode-execute cycle fetches, decodes and executes. RAM is random access memory. The benefit is that it is fast.

Why: Basic independent points only; no real linkage or application to the robot. Level 1.

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

Build a paper on this topic 56
Character Sets 18 questions Images 19 questions Sound 19 questions

2.3 Data storage and compression

Build a paper on this topic 24
Compression 18 questions Units & Conversion 6 questions

3.1 Hardware

Build a paper on this topic 77
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

Build a paper on this topic 124
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

Build a paper on this topic 37
Low and High Level Languages 19 questions Translators 18 questions

4.1 Networks

Build a paper on this topic 138
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

Build a paper on this topic 36
Network Security Risks 18 questions Preventing Network Security Risks 18 questions

5.1 Environmental

Build a paper on this topic 36
E-waste 17 questions Manufacturing Technology 19 questions

5.2 Ethical and legal

Build a paper on this topic 71
Data Protection Act 17 questions Impact of AI 18 questions Intellectual Property 18 questions Software Licences 18 questions

5.3 Cybersecurity

Build a paper on this topic 36
Malware 18 questions Social Engineering 18 questions

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

Activities Flashcards Revision notes

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.