Edexcel GCSE Computer Science (1CP2) Exam Questions

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.

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

• (Storage that is) non-volatile / keeps its data when the power is turned off (1)
• (Storage that is) used to store programs and data/files (for later use) (1)
• (Storage that is) not directly accessible by the CPU / not directly accessed by the CPU (1)

Allow both the non-volatile point and the stores programs and data point from one sentence if each idea is clearly stated, e.g. 'non-volatile storage that holds programs and data'.

Allow accessed via the CPU / must be copied into RAM before the CPU can use it for the third point.

Do not accept volatile / loses its data when the power is turned off.

Do not accept a description of primary storage, such as RAM or ROM.

Do not accept capacity.

Do not accept an example device on its own (e.g. hard disk drive).

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

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)