Edexcel GCSE Computer Science (1CP2) Exam Questions

• C Main memory (RAM) (1)
• The only correct answer is C. The correct answer is main memory (RAM); accept 'main memory', 'RAM' or 'random access memory'.
• A is not correct because the arithmetic logic unit performs arithmetic and logical operations
• B is not correct because the clock sends regular pulses to synchronise the components of the CPU
• D is not correct because the program counter holds the address of the next instruction, not the instructions and data

• A Arithmetic logic unit (1)
• The only correct answer is A. The correct answer is arithmetic logic unit.
• B is not correct because the control unit decodes instructions and controls the CPU
• C is not correct because main memory is not part of the CPU and stores data and instructions
• D is not correct because a register stores small amounts of data within the CPU

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:

• A read/write head moves over the surface of the disk (1) to read/write data by detecting or changing the magnetic alignment of areas of the surface (1)
• The head magnetises areas of the disk surface in different directions (1) so each area represents a binary 1 or 0 (1)
• Data is stored on concentric circles called tracks (1) which are divided into sectors (1)

Allow one mark for tracks/concentric circles on their own.

For the second mark in the first two bullets, the response must refer to the magnetic alignment/charge being detected or changed, not just that the head reads/writes data.

Do not award a mark for 'it is magnetic' or 'it stores data in binary' with no description of how the data is stored.

Do not accept descriptions of optical storage (e.g. a laser, pits and lands) or solid state storage (e.g. electric charges in chips).

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

• (The ECU) is more reliable/less likely to crash (1) because it only runs the one program/has a single purpose (1)
• (The ECU) cannot be affected by other software/viruses (1) because it cannot run other software/it can only run the program it was made for (1)
• (The ECU) is cheaper (1) because it has limited processing resources/less memory/simple components (1)
• (The ECU) uses less power (1) because it has limited processing resources/a simpler processor (1)
• (The ECU) is smaller (1) because it has fewer components/less memory than a general purpose computer (1)

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

A suitable benefit stated on its own earns one mark.

Do not accept a description or a location given as the reason, e.g. 'because it is part of the car', 'because it is inside the engine', 'because it is embedded'.

Do not accept a description of an embedded system on its own as the benefit, e.g. 'it does one specific job' or 'it is part of the car'.

Do not accept 'it is faster'/'it has a more powerful processor' as embedded systems have limited processing resources.

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)