Edexcel GCSE Computer Science (1CP2) Exam Questions

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

• The program's instructions (and the data it uses) are held in main memory/RAM (1) so the CPU fetches both the instructions and the data from that one memory (1)
• The CPU fetches the next instruction from main memory/RAM (1) using the address of the memory location that holds it (1)
• The CPU reads/fetches data from main memory/RAM (1) when an instruction needs it and writes the result back to main memory/RAM (1)
• The program's instructions are held in main memory/RAM while the program runs (1) and the CPU fetches them one at a time/one after another to be decoded and executed (1)

Allow 'memory' for main memory/RAM.

Allow 'gets' for fetches/reads.

For both marks, the development must say what the CPU does with the contents of main memory (fetches/reads/writes), not just that main memory is used.

Do not accept answers about the program being stored in secondary storage, such as on a hard drive, or about it being loaded from there.

Do not accept benefits such as the computer running faster or being easier for the user.

Do not accept naming CPU components (control unit, arithmetic logic unit, registers) or buses on their own, without saying what is stored or fetched.

Do not accept 'the computer stores data' on its own, without a link to the instructions of a program.

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

• It reads/monitors the temperature/humidity/light level using sensors (1) to switch the heaters/vents/lamps/watering system on or off when the reading is outside the set range (1)
• It compares the readings from the sensors with the set values/thresholds stored in its memory (1) to decide whether the conditions need to be changed (1)
• It monitors the light level using a light sensor (1) and turns the lamps on when the light falls below the level the plants need (1)
• It monitors the soil moisture using a soil moisture sensor (1) and turns the water pump/irrigation on when the soil is too dry (1)

For the second mark, the action/response must be linked to the sensor reading given in the first point.

Allow named sensors (temperature/humidity/light/soil moisture) and named outputs (heater, fan, vent/window, lamp, irrigation/water pump).

Do not accept answers that only name a sensor or only name an output, e.g. 'it has a temperature sensor and a heater', as there is no link between the reading and the control action.

Do not accept answers where a person switches the equipment on or off, as the embedded system controls the conditions automatically.

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

• More applications/programs can be open/run at the same time (1) because more instructions and data can be held in main memory at once (1)
• Programs run faster (1) because the CPU does not have to wait for instructions/data to be read/transferred from slower secondary storage (1)
• The CPU waits/idles for less time (1) because instructions and data can be transferred to the CPU more quickly from RAM (1)

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

Do not accept 'more files/photos/documents can be stored' or 'the computer has more storage' - this is a benefit of secondary storage, not RAM.

Do not accept 'the CPU becomes faster' or 'the clock speed increases'.

Indicative content

What an embedded system is

• An embedded system is a computer system that forms part of a larger device, such as the fitness tracker.
• It performs a single, dedicated or specific task rather than being a general purpose computer.
• It is often built around a microcontroller, which contains the processor, RAM and ROM on a single chip.
• Its software is held in ROM so the tracker can run its program as soon as it is switched on.

Functions in the tracker

• Monitoring the heart rate using a sensor and processing the readings so that they can be displayed on the screen.
• Counting steps using an accelerometer and using the count to calculate the distance walked or the calories burned.
• Tracking sleep by monitoring the wearer's movement during the night.
• Controlling the touch screen so that the user can move between displays.
• Managing the battery, for example stopping the charging when the battery is full and saving power when the tracker is idle.
• Sending the collected data to a smartphone using Bluetooth so that it can be viewed in an app. Accept any other specific function of the fitness tracker that an embedded system could control.

Why an embedded system is suitable for this device

• It has low power consumption, so the battery lasts longer between charges, which matters for a device that is worn all day.
• It is small and light, so it can be fitted into a wristband.
• Its dedicated function means it does not need a full operating system, so it is reliable and does not need restarting.
• The program is small and stored in ROM, so the tracker needs only a small amount of memory.
• It can be optimised for its specific tasks, so it responds quickly to the readings from its sensors.
• The low cost per unit keeps the tracker affordable for the customer.

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 an embedded system is, the functions it performs in the tracker and why it is suitable for the tracker.
• Do not award installing new software/apps, functions the tracker does not perform (such as playing music) or 'it is like a phone'.