Edexcel GCSE Computer Science (1CP2) Exam Questions

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

• Stores programs (including the operating system) and data that are not currently in use (1) so that they can be loaded into RAM/main memory when needed (1)
• Keeps files/programs/data when the power is turned off (1) which happens because it is non-volatile (1)
• Stores files/data for backup or archiving (1) so that they can be recovered if the originals are lost/corrupted (1)

A correct role on its own earns one mark; the second mark requires a linked development.

Accept either order if both the role and the link are given.

Do not accept 'it is non-volatile' on its own, unless it is linked to keeping data when the power is turned off.

Do not accept answers that only name a storage type (magnetic, optical, solid state) without describing a role.

Do not accept responses that describe primary storage/RAM, e.g. storing the data/instructions the CPU is currently working on, or that secondary storage makes the computer run faster.

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

• The CPU can only fetch/read instructions from main memory/RAM (1) so the instructions of a running program must be copied/loaded into RAM before they can be executed (1)
• RAM is faster to access than secondary storage (1) so the instructions can be fetched quickly enough for the CPU to execute them (1)
• The CPU needs the instructions in RAM to fetch and execute them (1) because the fetch-decode-execute cycle reads each instruction from main memory/RAM (1)
• The address of the next instruction is sent to RAM on the address bus (1) so the instruction can be transferred to the CPU/registers for decoding/execution (1)

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

Allow the point and reason in either order if they are linked.

Do not accept answers that only say the CPU needs instructions, or that RAM is faster, without linking this to fetching/executing the instructions.

Do not accept answers that only say RAM holds data and instructions without linking this to the fetch-decode-execute cycle.

Do not accept 'RAM is permanent/non-volatile storage, so the instructions are kept safe' - RAM is volatile.

The response does not need to name the address bus or the fetch stage for full marks; a linked reason that explains why instructions must be in RAM (for example, the CPU can only fetch from RAM, or RAM is faster than secondary storage) is enough.

Indicative content

Magnetic storage

• A magnetic hard disk drive stores data on a magnetic platter that spins, with a read/write head on an actuator arm that moves over its surface.
• The read/write head magnetises small areas of the platter to represent binary 1s and 0s, and reads the magnetic pattern back when the data is needed.
• The data is held on concentric tracks that are divided into sectors. (Accept data being stored magnetically without further detail, but a vague 'it uses a magnet' is not enough for this point.)
• The platter and the read/write head are sealed inside the drive unit because of the precision needed.

Solid state storage

• A solid state drive stores data in flash memory chips and has no moving parts.
• A large electric current forces electrons through a barrier and traps them in a floating gate; the presence or absence of this trapped charge represents a 1 or a 0. (Accept either convention for which charge state represents a 1 and which represents a 0.)
• The charged cells are detected to read the data back. (Accept: the data can be erased and rewritten by applying a new current.)
• As there is no disk to spin to the correct position and no arm to move, data can be read from and written to solid state storage very quickly.

Suitability for the company's video files

• A magnetic HDD has a very large capacity and is generally cheaper per gigabyte than an SSD of the same capacity, which suits a company that stores many large video files.
• An SSD has very fast read/write speeds, so the company's large video files open and save quickly while they are being edited.
• An SSD has no moving parts, so it is more durable if the company's computers are carried between filming locations.
• A magnetic HDD could store finished videos as an archive and an SSD could hold the project being edited, so the company gets high speed while editing and low-cost capacity for storage.

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 3 answers must give accurate accounts of how data is stored on both magnetic and solid state storage and sustain a line of reasoning that applies at least one of them to the company's video files. An answer that covers only one storage type, or that describes both types without any application to the company, cannot go above Level 2.
• Do not accept descriptions of optical storage (pits and lands, a laser) as magnetic or solid state storage, and do not accept 'magnetic storage uses a laser' or 'solid state storage is volatile' or 'solid state storage is RAM'.