Edexcel GCSE Computer Science (1CP2) Exam Questions

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:

• It is a computer/processor built into a larger device (1) to carry out a single dedicated task/function (1)
• It is a combination of a processor, memory and input/output in one unit (1) that controls the device it is part of (1)
• It is a computer that forms part of another device (1) so it is not used as a general purpose computer (1)

Allow 'forms part of another device' or 'inside another device' for the first mark.

Do not award the second mark for a separate fact that is not linked to the first point, e.g. 'It is built into a device and it uses little power' would earn only the first mark (1).

Do not accept 'a small computer' on its own, with no reference to being part of another device or performing a dedicated task.

Do not accept 'a computer that controls a device' on its own, with no reference to it being built into/part of a larger device or carrying out a dedicated task.

Do not accept 'it performs a single dedicated task' on its own, with no reference to it being built into/part of a larger device.

Do not accept descriptions of a general purpose computer, e.g. 'it can run many different programs' or 'new software can be installed'.

Do not accept 'it is a system that is embedded in another system' as this repeats the term in the question.

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

• Decodes each (fetched) instruction (1) to work out which operation is needed / which components should carry it out (1)
• Coordinates/directs the other components (1) by sending control signals along the control bus (1)
• Fetches the next instruction (1) by sending its address to main memory along the address bus (1)
• Sends a read/write control signal to main memory (1) so that the instruction or data is transferred during the fetch/execute stage (1)

Do not accept answers about synchronising the CPU or timing the cycles (that is the role of the clock).

Do not accept answers about carrying out arithmetic or logical operations (that is the ALU).

Do not accept answers about holding data or the results of instructions (that is registers/main memory).

Do not accept generic answers that only say the CU controls the CPU or processes instructions, with no linked development.

Only award one mark for a response that only repeats that the CU sends control signals; the second mark needs a linked outcome such as coordination, a memory read/write, or fetching an instruction.

Do not accept 'during the decode stage' as the development for the decoding point, as it restates the question.

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

• Decodes/interprets/translates the instruction (1) to work out what the instruction is/what operation is required (1)
• Sends control signals to the other components (1) so that the correct component carries out the instruction (1), e.g. the ALU/main memory
• Controls the fetch of the instruction from main memory (1) because the address of the next instruction is sent via the address bus (1)
• Controls the fetch of the next instruction from main memory (1) by sending a control signal/read signal to main memory (1)

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

For the decode point, 'decodes the instruction' alone gains 1 mark; a second mark needs the purpose of decoding, i.e. working out what the instruction is/what operation is required.

Do not accept 'it controls the CPU' on its own, without naming a task in the cycle.

Do not accept 'it fetches the instruction from memory' on its own, as this describes the fetch step rather than the control unit's role; credit only if linked to controlling/signalling the fetch.

Do not accept carrying out arithmetic/logical operations, as these are carried out by the ALU, or holding the address of the next instruction, as this is the program counter.

Do not accept storing the instruction in a register (e.g. MAR/MDR), as this is not the role of the control unit.

Indicative content

What embedded systems are used for in the drone

• An embedded system is a computer built into a larger device that performs a single, dedicated function as part of that device.
• The drone contains several embedded systems, and each one is dedicated to a task such as flight control, navigation, obstacle detection or battery monitoring rather than being a general-purpose computer.
• The flight controller embedded system processes data from the drone's sensors and changes the signals sent to the rotors, so the drone stays stable and can be steered while carrying a parcel.
• The GPS receiver embedded system works out the drone's position and uses it to navigate along the route to the customer's address.
• The camera embedded system captures images or video that are processed to detect obstacles, such as trees, buildings or overhead cables, in the drone's path.
• Sensor embedded systems, for example ultrasonic or infrared sensors, measure the distance to the ground and to obstacles so the drone can land and avoid collisions.
• The battery management and communication embedded systems monitor the charge and send the drone's status and location to the control centre, and the rotor-control embedded systems drive the rotors so the drone can take off, hover and land.

Benefits of using embedded systems in the drone

• Embedded systems use little power, so the drone can fly for longer and deliver more parcels on one charge.
• They are small and light, which is important because a heavier drone needs more power to stay in the air.
• Because each embedded system is dedicated to one task, it can respond quickly and reliably, so the drone can change direction in time to avoid an obstacle.
• Combining the processor, memory and input/output in one unit reduces the number of separate components and the cost per drone, so a fleet of delivery drones is cheaper to build.
• Embedded systems allow the drone to fly autonomously, so the company does not need a human pilot for every delivery.
• Programs are held in ROM, so the drone's behaviour is consistent and predictable each time it flies.

Any drawbacks or limitations of using embedded systems in the drone

• Each embedded system has limited processing power, so the drone may not be able to run complex obstacle-recognition software and could fail to identify an unusual obstacle.
• They have limited storage and RAM, so the drone cannot store much flight data or video on board and must send it to the control centre.
• The software is held in ROM and is difficult to update, so fixing a bug or adding a new feature may mean returning the drone or connecting it to a computer.
• The embedded systems are dedicated to the drone, so they cannot easily be reused for a different task if the drone is retired.
• If an embedded system fails, the drone may crash, which could injure people or damage property, so robustness is essential.
• A general-purpose computer would be too large and heavy for the drone, so the drone has to use these limited dedicated systems and cannot run general-purpose software.

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 responses must cover what embedded systems are used for in the drone and both benefits and drawbacks/limitations, with reasoning applied to the delivery drone. Do not accept general-purpose computer uses such as connecting to Wi-Fi to play videos, installing new software, apps or games, or using a server; do not accept the drone itself as a single embedded system unless a specific dedicated function is explained.
• A definition of an embedded system on its own, with no application to the drone, cannot lift an answer above Level 1; limited storage and inability to be repurposed must be linked to the drone, for example little flight data can be stored or the system cannot be reused for another task, to gain credit.