Edexcel GCSE Computer Science (1CP2) Exam Questions

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

• The program's instructions (and the data it uses) are held in main memory/RAM (1) so the CPU fetches both the instructions and the data from that one memory (1)
• The CPU fetches the next instruction from main memory/RAM (1) using the address of the memory location that holds it (1)
• The CPU reads/fetches data from main memory/RAM (1) when an instruction needs it and writes the result back to main memory/RAM (1)
• The program's instructions are held in main memory/RAM while the program runs (1) and the CPU fetches them one at a time/one after another to be decoded and executed (1)

Allow 'memory' for main memory/RAM.

Allow 'gets' for fetches/reads.

For both marks, the development must say what the CPU does with the contents of main memory (fetches/reads/writes), not just that main memory is used.

Do not accept answers about the program being stored in secondary storage, such as on a hard drive, or about it being loaded from there.

Do not accept benefits such as the computer running faster or being easier for the user.

Do not accept naming CPU components (control unit, arithmetic logic unit, registers) or buses on their own, without saying what is stored or fetched.

Do not accept 'the computer stores data' on its own, without a link to the instructions of a program.

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

• Data is stored on (flash) memory chips/cells (1) as a pattern of electrical charges (1)
• A current/voltage forces electrons through a barrier (1) so that they are trapped (or not trapped) to hold/represent a value (1)
• Cells with a trapped charge and cells with no trapped charge (1) represent 1s and 0s/binary (1)
• The trapped charge remains when the power is turned off (1) so the data is not lost/it is non-volatile (1)

Do not accept responses that describe magnetic storage, e.g. magnetised platters, spinning disks or read/write heads, or optical storage, e.g. lasers, pits and lands.

Do not award a mark for 'it is solid state' or 'it has no moving parts' without a description of how the data is stored.

Do not award a mark for restating the stem, e.g. 'a laptop uses an SSD' or 'an SSD uses flash memory'.

'Data is stored as electrical charges' on its own, with no reference to memory chips/cells or to how the charge is held, earns a maximum of one mark (1).

A response that only describes electrons being trapped, with no link to how the value/data is represented, earns one mark (1). The second mark needs a link such as trapped and not trapped charge representing 1s and 0s, or the trapped charge being kept so the data is not lost.

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

• The battery lasts longer/needs charging less often (1) because embedded systems have low power consumption/use less power (1)
• It can be made small/light enough to wear on the wrist (1) because the processor, memory and input/output are combined on a single chip/microcontroller (1)
• It can carry out the step-counting function reliably (1) because it runs a single/dedicated program and cannot install other software (1)
• It has a low cost per unit (1) because it uses fewer/less powerful components than a general purpose computer (1)

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

Award one mark for a valid point stated on its own, e.g. 'it is small/light enough to wear on the wrist' (1) or 'its battery lasts longer before it needs charging' (1).

Accept the same linked ideas in either order, e.g. 'it uses less power (1) so the battery lasts longer (1)'.

Do not accept 'it uses less power'/'low power' on its own as a complete explanation; it must be linked to the battery lasting longer/needing charging less often for the second mark.

Do not accept an expansion that simply restates the point, e.g. 'it is small (1) so it fits on the wrist' earns only the point mark; 'fits on the wrist' is not a linked cause and is not enough for the second mark.

Do not accept 'the battery is small' as the linked reason for low power consumption.

Do not accept responses that say other software/apps can be installed on an embedded system (0); embedded systems have a single/dedicated function and cannot install new software.

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.