Edexcel GCSE Computer Science (1CP2) Exam Questions

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:

• It controls the motors/rotors (1) so that the drone can take off, hover, turn and land (1)
• It keeps the drone stable/level automatically (1) by taking readings from a sensor (accelerometer/gyroscope/GPS) (1)
• It receives signals from the remote control (1) and changes the speed of the motors to steer the drone (1)
• It monitors the battery level (1) and brings the drone back to the ground before the battery runs out (1)

The development must relate to the function given in the point.

Accept a named function that the embedded system controls, e.g. 'it keeps the drone level', as the first mark (1).

Award the second mark only when the development gives a specific outcome or detail of that function, e.g. 'so that the drone can take off, hover, turn and land' or 'by changing the motor speeds to keep it level'.

Do not award the second mark for a generic outcome such as 'so it works', 'so it can fly' or 'so the drone moves'.

A bare 'it controls the motors so it can fly' therefore earns the first mark only.

Allow any other specific function of a drone that is carried out by the embedded system.

Do not accept 'it flies the drone' / 'it is the drone's brain' / 'it makes the drone work' without a named function being controlled.

Do not accept answers that describe the user or the remote control flying the drone with no function carried out by the embedded system.

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

• The address bus carries the address of the next instruction (1) so the CPU can locate/fetch it from main memory/RAM (1)
• The address bus carries the address of the memory location to be read (1) so the instruction/data stored there can be located/accessed (1)
• The CPU needs to know where the next instruction is stored (1) so the address bus sends the address to main memory/RAM (1)

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

Allow 'from the program counter/PC' as part of the point for one mark, e.g. the address bus carries the address from the program counter (1), but the second mark needs the destination or purpose (e.g. to locate/fetch the instruction in main memory/RAM).

Do not award the second mark for naming the program counter/PC alone.

Do not accept answers that say the address bus carries data/instructions from main memory to the CPU, as these travel on the data bus.

Do not accept answers that say the address bus stores the address.

Do not allow an answer that only restates that the address bus carries addresses without saying which address or why it is needed.

Indicative content

the role of RAM in the stored program concept

• In the von Neumann stored program concept, a program's instructions and the data it uses are held together in main memory.
• RAM holds the instructions and data of the program that the CPU is currently processing.
• The CPU fetches each instruction from RAM during the fetch-decode-execute cycle, so a program must be in RAM before it can be run.
• RAM is directly accessible by the CPU, so instructions can be fetched quickly enough for the CPU to keep working.

what happens to a program when it is opened

• When a program is opened, a copy of its instructions and data is transferred from secondary storage, such as the hard drive, into RAM.
• The operating system loads the program into RAM so that the CPU can start fetching and executing its instructions.
• When the program is closed, it is removed from RAM, and the space it used is free for another program.
• If a computer does not have enough RAM, the program may not open, or another open program has to be closed first.

why the CPU cannot execute a program directly from secondary storage

• Secondary storage, such as a hard disk drive, is much slower to access than RAM.
• The CPU can process instructions much faster than secondary storage can supply them, so the CPU would have to wait and would not be working at full speed.
• RAM is fast electronic memory with no moving parts, so data can be read from it in a fraction of the time taken by a magnetic hard disk drive.
• Running the school's programs directly from secondary storage would make the computers in the IT room very slow to use.

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 both the role of RAM in the stored program concept and the speed difference between RAM and secondary storage, with a reason such as the CPU having to wait for instructions.
• Answers that make only basic, independent points, such as what RAM is, that a program is copied into RAM when it is opened, or that RAM is faster than a hard drive, without linking them to explain why the CPU would have to wait for instructions, are limited to Level 1.
• Do not accept statements that RAM is permanent storage, that RAM replaces secondary storage, or that secondary storage is read-only.