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Edexcel GCSE Computer Science (1CP2) Exam Questions

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4 questions · 15 marks

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1Short recall2 marksPrimary Memory Swap Remove

A computer is designed using the von Neumann stored program concept.

Define the term stored program concept.

[2 marks]
Mark scheme

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

  • The program instructions and data are stored together in main memory/RAM (1)
  • The same memory is used for both instructions and data (1)
  • The instructions are fetched from main memory and executed by the CPU (1)
  • The instructions are fetched and executed one at a time / in sequence (1)
  • The program can be changed/replaced by loading new instructions into memory, without changing the hardware (1)

Do not accept the program is stored in secondary storage / on the hard disk.

Do not accept the program is stored in the CPU / in registers.

Example answers and how they were marked
Full marks2/2

The program instructions and the data are stored together in main memory, and the CPU fetches the instructions one at a time and executes them.

Why: Creditworthy point that instructions and data are stored in the same main memory (1) and the linked point that the CPU fetches and executes them from memory (1).

Some marks1/2

The program is held in the main memory (RAM) so that the computer can run it.

Why: Earns the point that the program instructions are stored in main memory (1), but does not say that the CPU fetches and executes them, so the second mark is not earned.

No marks0/2

The program is stored on the hard disk and loaded into the CPU when it is run.

Why: Both parts are misconceptions named in the Do not accept lines: the stored program concept keeps the instructions in main memory, not on secondary storage or in the CPU.

2Short recall1 markSecondary Memory Swap Remove

Data is stored on optical discs as pits and lands.

Name the component in an optical disc drive that reads this data.

[1 mark]
Mark scheme

Award one mark for:

  • Laser (1)

Allow laser beam

Do not accept read/write head

Do not accept pits

Do not accept lands

Do not accept reflective surface

Do not accept magnet/magnetic

Example answers and how they were marked
Full marks1/1

Laser

Why: Laser is the creditworthy answer (1).

No marks0/1

A read/write head

Why: Read/write head is not accepted by the mark scheme; it reads magnetic media, not optical discs, so no marks are awarded.

No marks0/1

Pits and lands

Why: Pits and lands are what the laser reads, not the component that reads the data, so the mark scheme does not accept them.

3Discuss6 marksSecondary Memory Swap Remove

An independent film studio sells its films on discs. It also offers the same films as downloads. The studio is deciding whether to keep selling films on optical discs.

Discuss the use of optical storage for selling films.

Your answer should include:

  • how data is stored on optical media
  • the benefits of optical discs for selling films
  • the drawbacks of optical discs for selling films.

You do not need to consider other types of secondary storage.

[6 marks]
Mark scheme

Indicative content

How data is stored on optical media

  • Data is stored as pits and lands burnt or pressed into a spiral track on the disc.
  • A laser beam is shone at the disc and the light that is reflected back is measured; pits and lands reflect the light differently.
  • The differences in the reflected light are read as binary 1s and 0s.

Benefits of optical discs for selling films

  • Optical discs are cheap to mass produce once the master disc has been pressed, so the studio can sell each film at a low price.
  • A disc is small and light, so a customer can easily store it, carry it home or give it as a gift.
  • A Blu-ray disc can hold a whole high-definition film (up to 50 GB), so a customer can watch the film without an internet connection.
  • Artwork can be printed on the disc and its case, which helps the studio sell the film.

Drawbacks of optical discs for selling films

  • A DVD holds only about 8.4 GB, so a high-definition film with extra features may not fit on one and the studio would need to sell it on a Blu-ray instead.
  • Optical discs are easily scratched, which can cause read errors so the film will not play.
  • Many modern devices, such as some laptops, no longer have a disc drive, so some customers would not be able to play the film.
  • Discs can be affected by heat and sunlight, so they may deteriorate over time.

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 2 requires points to be linked or developed, for example a benefit or drawback explained in terms of the studio or its customers. An answer that only lists basic, independent points, with no linkage, is limited to Level 1.
  • Level 3 requires all three areas and a judgement about whether the studio should keep selling films on optical discs. Do not credit magnetic storage or solid state storage as a description of how optical media stores data; credit these only where they are compared with optical media.
Example answers and how they were marked
Full marks6/6

Optical media stores data as pits and lands burnt into a spiral track. A laser beam is shone at the disc and the reflected light is measured; pits and lands reflect it differently, and this pattern is read as binary 1s and 0s. Optical discs are cheap to mass produce, so the studio can sell each film at a low price, and a disc is small and light so a customer can store it or give it as a gift. A Blu-ray holds a whole high-definition film and can be played without an internet connection. However, a DVD may not hold a high-definition film with extra features, so the studio would need a Blu-ray, and discs are easily scratched, which can cause read errors so the film will not play. Many modern laptops have no disc drive, so some customers could not play the film. Overall the studio should keep selling discs as well as downloads, because the discs are cheap to produce and give customers a copy that works without an internet connection, even though some customers will prefer to download.

Why: Explains how data is stored on optical media using pits, lands, reflected light and binary (AO1); gives benefits applied to selling films (cheap mass production, portability, Blu-ray holds a film and plays offline) and drawbacks (DVD capacity, scratches causing read errors, no disc drive in modern laptops); ends with a sustained judgement and recommendation, so it meets the Level 3 guidance.

Some marks2/6

Optical storage uses a laser to read pits and lands. It is cheap to make discs, so the studio can sell them cheaply. Discs are portable. But they can be scratched and damaged. Some computers don't have a disc drive.

Why: Basic point about how data is stored, a laser reading pits and lands (1), plus basic points about benefits (cheap to produce, portable) and drawbacks (scratched, no disc drive), but the points are independent and undeveloped with no linkage or application to the studio, so it is the top of Level 1: 2 marks.

No marks0/6

Optical storage uses magnets to store data. The film studio should use optical discs because they are very fast and have a large capacity. They are not affected by scratches.

Why: No creditworthy points. Confuses optical storage with magnetic storage; claims it is fast, has a large capacity and is not affected by scratches, all of which are incorrect. Level 0.

4Discuss6 marksStored Program Computers Swap Remove

A college is buying new computers for its computer science classroom. A technician explains that the CPU uses three buses to communicate with main memory and other components.

Discuss the role of the address bus, the data bus and the control bus in the fetch-decode-execute cycle.

Your answer should include:

  • what each bus carries
  • the direction in which each bus carries it
  • the role of the buses in the fetch-decode-execute cycle.
[6 marks]
Mark scheme

Indicative content

What each bus carries

  • The address bus carries the address of a memory location that the CPU wants to read from or write to.
  • The data bus carries data and instructions between the CPU and main memory, and between the CPU and other components such as the input and output controllers.
  • The control bus carries control signals, such as read and write, that coordinate the activities of the computer.
  • The clock is a separate component that sends regular pulses, and the control bus carries the signals that keep the other components in time with those pulses.

Direction

  • The address bus is one-way, carrying addresses from the CPU to main memory.
  • The data bus is two-way, so data and instructions can travel both to and from the CPU.
  • The control bus carries control signals from the control unit to the other components, and it is not the clock signal itself.
  • The number of bits in the address bus determines how many memory locations can be addressed, and the number of bits in the data bus determines how much can be transferred at one time.

The role of the buses in the fetch-decode-execute cycle

  • Fetch: the address of the next instruction, held in a register in the CPU, is placed on the address bus so that main memory knows which location to read.
  • Fetch: the control unit sends a read signal on the control bus to main memory.
  • Fetch: the instruction held in that location is returned to the CPU on the data bus.
  • Decode: the control unit decodes the instruction and sends control signals on the control bus to set up the other components, for example telling the ALU which operation to carry out.
  • Execute: the address of any data needed is placed on the address bus, a read or write signal is sent on the control bus, and the data itself travels between the CPU and main memory on the data bus.
  • The cycle repeats, with each step taking place in time with a pulse from the clock.

Level 3 responses must cover all three buses and link them to the fetch-decode-execute cycle, including the fetch stage and at least one of the decode and execute stages. Answers that describe each bus correctly but link none of them to a stage of the cycle are limited to Level 1.

Do not accept 'the address bus carries data', 'the data bus carries addresses', 'the data bus carries instructions only during the fetch stage', 'the control bus carries the clock signal' or 'the control bus is the clock'; the clock is a separate component whose pulses the control signals coordinate with.

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

At the start of the fetch stage the address of the next instruction, which is held in a register, is placed on the address bus, which is one-way, so that main memory knows which location to read. The control unit sends a read signal on the control bus, and the instruction held at that address is returned to the CPU on the data bus, which is two-way. In the decode stage the control unit works out what the instruction means and sends control signals on the control bus to set up the other components, for example telling the ALU which operation to carry out. In the execute stage, if the instruction needs data from memory, the address of that data is placed on the address bus, a read or write signal is sent on the control bus and the data itself travels on the data bus. Every step happens on a pulse from the clock, which is a separate component, and the control bus carries the signals that keep the components in time with it. The widths of the buses matter too: more address bits mean more memory locations can be addressed and more data bits mean more can be moved at once.

Why: Level 3 (6 marks): all three buses are covered, with what each carries and its direction, and each is linked to the fetch, decode and execute stages, plus the role of the clock and the effect of bus widths.

Some marks2/6

The address bus carries addresses from the CPU to the memory and it is one-way. The data bus carries data and it is two-way. The control bus carries control signals. During the fetch stage the CPU fetches the instruction from memory using these buses.

Why: Level 1 (2 marks): each bus is named with a basic correct statement (address bus carries addresses one-way, data bus is two-way, control bus carries control signals), but no bus is linked to a stage of the cycle, so the guidance line limits this to Level 1; the general mention of the fetch stage is not tied to any bus.

No marks0/6

The address bus carries the data to the CPU. The data bus carries the addresses to the memory. The control bus is the clock that makes the CPU run faster.

Why: Level 0 (0 marks): the address bus and data bus roles are swapped, which the scheme says not to accept, and the control bus is wrongly described as the clock, which is also not accepted, so there is no rewardable content.

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

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

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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 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

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