Edexcel GCSE Computer Science (1CP2) Exam Questions

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

• It keeps a record of which memory addresses/areas belong to each program and to the operating system (1) so it knows which addresses a program is allowed to use (1)
• Each program is given its own area of main memory (1) so a program cannot write to the addresses used by another program or by the operating system (1)
• The memory used by the operating system is marked as protected/reserved (1) so a program that tries to write to it is blocked/causes an error (1)
• The address a program writes to is checked against the record of its allocated area (1) and the write is stopped if the address is outside that area (1)

Allow the memory being protected to be that of the operating system or of another program.

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

Do not award generic answers such as 'the operating system manages memory' or 'the operating system keeps track of memory'.

Do not award responses about stopping programs using too much memory or allocating memory, as these are not about protecting memory being overwritten.

Do not award responses about virtual memory, paging or moving processes to secondary storage.

Do not award responses about firewalls, antivirus software or passwords.

Indicative content

User accounts

• Each student and teacher should have their own user account, so the operating system can identify the person who is logged on.
• The operating system keeps a record of all valid users on the computer, so unknown users are not allowed to log in.
• A separate home area or folder can be created for each account, so a student's saved work is kept apart from other users' work.
• An account can be disabled when a student leaves the school, so they can no longer access the computers.

Authentication

• A username and password can be required at login, so only users with the correct details can use the computer.
• The operating system checks the entered password against the stored password for that account before allowing access.
• Users should be encouraged to choose a strong password, which makes it harder for someone else to guess and log in.
• The operating system can lock an account after several failed login attempts, which reduces the chance of someone trying passwords repeatedly.

Benefits for the school

• Many students can share the same computers because each person's files are kept separate.
• Work is less likely to be deleted or changed by another student, because users only see their own files.
• The school can see which account was used on a computer, so misuse can be traced to a user.
• Teachers can be confident that only authorised people can use the library computers.
• The school does not need a separate computer for every student, so it saves money.

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)

Level 3 responses must cover both user accounts and authentication, and apply them to the school library.

Do not accept general operating system functions such as file management or process management unless they are explicitly linked to managing users.

Indicative content

Ease of learning, use and debug

• High-level language statements are written in English-like words and mathematical symbols, so the students can read the quiz game code and understand what each line does.
• The language is easier to learn than a low-level language, so students who are new to programming can start writing the quiz game quickly.
• Errors are easier to find and fix because the code is readable; for example, the students can check a line that updates a score against the rule they intended.
• The students do not need to know how the processor carries out each statement, so they can concentrate on the quiz questions and rules.

Data structures

• High-level languages provide lists or arrays, so the names and scores of all the players can be stored under one name and processed with a loop.
• A record can store a player's name and score as one item; in some languages a dictionary or class can be used instead, which keeps related data together.
• Using a data structure makes the code shorter and easier to understand than separate variables for every player's name and score.

Built-in functions and library routines

• High-level languages provide built-in functions such as print and input, so the students can display a question and read a player's answer without writing the underlying code.
• Library routines such as a random number generator can be used to choose quiz questions, saving the students time.
• String-handling routines can check or compare a player's answer, so the students do not have to write these routines themselves.
• Reusing tested routines reduces the amount of code the students write and can reduce errors in the quiz game.

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: Credit only points applied to the quiz game and the students; comparison with low-level languages is not required, but a correct contrast may support a point if it is applied. Do not award generic claims such as 'high-level programs run faster', 'work on any computer' or 'students do not need to learn syntax' unless they are justified for the quiz game.

Level 3 responses must cover all three bullet areas with linked reasoning that explains why the characteristic helps the students finish the game quickly with few errors; an answer covering only two bullet areas is limited to Level 2. Do not award the idea that high-level code is already machine code or is understood directly by the processor. Accept dictionaries or classes as equivalents of records.