Edexcel GCSE Computer Science (1CP2) Exam Questions

• A Address bus (1)
• The only correct answer is A. The correct answer is address bus. Do not accept 'address' on its own.
• B is not correct because the control bus carries control signals in both directions between the CPU and other components
• C is not correct because the data bus carries data in both directions between the CPU and main memory
• D is not correct because the system bus is the collection of all three buses

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

• A compiler produces object code/machine code/an executable (file) (1) whereas an interpreter produces no object code/translated file (1)
• A compiler produces a machine code file (1) that can be run on its own/without the compiler/translator being present (1)
• An interpreter produces no object code/file (1) because it translates and executes each line instead of saving translated code (1)
• The compiler's output can be saved/stored (1) and run again later, while interpreted code has to be translated again each time it is run (1)

Allow binary for machine code.

Allow executable/an executable for object code.

Do not accept responses about translating the whole program, reporting errors or the speed of execution.

Do not accept 'the interpreter translates/executes one line at a time' on its own: this is how it translates, not what it produces. It earns the development only when linked to no object code/translated file being produced.

Do not accept the interpreter producing object code/an executable.

Indicative content

How files and folders are organised

• The operating system creates a folder structure, so the business can keep each client's or event's photographs together.
• The operating system allocates each image file to a folder and records its file path, so the image can be located again.
• The operating system can move, copy and delete files and folders, so staff can remove unwanted images and keep the disk tidy.
• The operating system records file attributes such as size, type and date, so staff can sort and identify images.
• A folder structure that is not used consistently can make images slow to find, because files may be saved in the wrong client folder.

How files are named and saved

• The operating system lets an employee choose a file name and extension, so an image can be identified and opened by the correct application.
• The operating system saves a file to the folder the employee chooses, so a new image is stored with the correct client.
• The operating system checks whether a file with the same name already exists and warns the employee before it is overwritten, so original photographs are not lost.
• The operating system stores the file path with the file, so the business can retrieve the image later.
• If employees choose inconsistent file names, images can be difficult to identify when the business needs them.

How access to files is controlled for the employees

• The operating system stores user accounts and passwords, so each employee must log in before opening client images.
• The operating system sets access rights, so some employees can view images but not edit or delete them, which protects original photographs.
• An administrator account can change access rights, so the business can decide who may delete or edit client files.
• If employees share passwords, access rights are not effective, so images could be changed or deleted by the wrong person.
• If access rights are too restrictive, employees may be unable to do their work, so the business must set them carefully.

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

• Accept file extensions, file paths, file attributes, directory/folder structure, read-only access, read/write access, administrator and user accounts. Do not accept 'the OS controls/organises files' without a named task, or memory management, process management or peripheral management as file management.
• Level 3 responses must cover all three bullets, with at least one benefit or drawback applied to the business and a judgement. A list of features with no application is limited to Level 1; Level 2 requires at least two bullets covered with some linkage to the business.

Indicative content

Machine independence

• A high-level language is machine independent, so the same source code can be run on different types of computer with few or no changes.
• The company can write the program once and sell it to users with different computers, without rewriting the code for each type of computer.
• Only one version of the program needs to be written and maintained, so development takes the company less time.

Processor specificity

• A low-level language is processor-specific, so a program written for one processor will not run on a different processor without being rewritten.
• Assembly language instructions depend on the instruction set of the particular processor, so the company would need a separate version of the program for each type of computer.
• Writing a separate low-level version for every type of computer would take the company much longer than writing one high-level program.
• Low-level code gives direct control of the hardware of one processor, so it is better suited to device drivers than to a program that must run on many different computers.

Translation

• High-level source code is translated for each type of computer by a compiler or an interpreter, so one version of the source code is enough for all the users.
• Assembly language is translated into machine code by an assembler, and the assembler produces machine code for one specific processor only.
• Machine code is already in a form that one particular processor can execute directly, but the same machine code will not run on a different processor.
• Each high-level statement translates into several machine code instructions, so the programmer does not need to know the instruction set of the processor.

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 high-level machine independence and low-level processor specificity, with the effect on the company's decision.
• Do not award low-level language, assembly language or machine code as portable, or 'high-level languages are written in English/like English' as a reason for machine independence.