Edexcel GCSE Computer Science (1CP2) Exam Questions

• B RAM is faster to access than secondary storage (1)
• The only correct answer is B. The correct answer is RAM is faster to access than secondary storage.
• A is not correct because RAM is volatile
• C is not correct because RAM has a smaller capacity than secondary storage
• D is not correct because RAM is more expensive than secondary storage

Award one mark for:

• Volatile (1)

Allow volatile memory / it is volatile.

Do not accept non-volatile, ROM, RAM or temporary/short term memory on their own, as these are not the term asked for.

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

Characteristics of embedded systems

• An embedded system performs a single, dedicated task, so each self-service checkout is built only to scan, weigh and price items and cannot be used for any other job.
• An embedded system has limited processing resources and storage, which is enough for the checkout to scan barcodes, weigh items and display prices.
• An embedded system normally has a simple operating system held in ROM, so a checkout is less likely to fail while a customer is using it.
• Embedded systems have low power consumption, so a row of checkouts can be left running all day without using much electricity.
• Embedded systems are small and low cost per unit, so one can be built into each checkout unit and the supermarket can afford one at every till.
• An embedded system has a limited user interface, so the checkout only shows its own screens to the customer.
• The firmware of an embedded system is not normally changed by the customer, although a technician can update it when the supermarket changes the checkout's software.

Uses of embedded systems in the checkout

• The checkout uses an embedded system to read the barcode scanner, so the correct price for each item is found quickly.
• The checkout uses an embedded system to read the weighing scales, so the weight of the items can be checked against the product that was scanned.
• The checkout uses an embedded system to control the touchscreen that shows the customer what to do and how much to pay.
• The checkout uses an embedded system to respond quickly to each scan, because it only carries out the checkout's own tasks, which keeps the queues moving.
• The checkout uses an embedded system so that it keeps working for long periods without being restarted, which means customers can use it without a member of staff.

Comparison with general-purpose computers

• A general-purpose computer can run many different programs, whereas the checkout's embedded system runs one dedicated program, so it cannot be used for other jobs.
• A general-purpose computer loads a full operating system when it starts and has other software running, so it can slow down or need restarting, whereas the checkout is not slowed down by other programs.
• A general-purpose computer has far more processing power and memory than the checkout needs, so using one would be more expensive and would take up more space than an embedded system.
• A general-purpose computer is designed for users to install new software, but the checkout's embedded system runs fixed firmware, so customers cannot change what the checkout does.

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)

Level 3 responses must consider both the characteristics of embedded systems and what the checkout uses them for, and must make a comparison with a general-purpose computer. Answers that only list characteristics or checkout tasks without linking them to the checkout are limited to Level 1.

Do not accept claims that embedded systems are faster than general-purpose computers or that they can run many different programs, as embedded systems have limited processing resources and carry out a single, dedicated task.