Edexcel GCSE Computer Science (1CP2) Exam Questions

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

• An arithmetic operation, e.g. addition/subtraction/multiplication/division (1)
• A logical operation, e.g. comparing two values (is A > B?) / using AND, OR, NOT (1)

Do not accept decoding instructions, fetching instructions or controlling the timing of the CPU, as these are carried out by the control unit.

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 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 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.