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.

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

• Each router chooses the best route at the time (1) so when a route becomes busy/congested or fails, later packets are forwarded along a different path (1)
• Routers forward each packet separately (1) so the path a packet takes depends on the traffic conditions when that packet arrives (1)
• A router may send a packet to a different next router (1) if its routing table shows a better/less congested route for that packet (1)
• Traffic on the internet changes (1) so no single path is kept for the file and each packet can use whichever route is best when it is sent (1)

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

Allow reference to a routing table, or to how a router decides the route, as part of the linked reason.

Do not accept 'the packets have different IP addresses' because all packets from the same file have the same destination IP address, even though their routes can differ.

Do not accept 'the internet is busy' or 'there is a lot of traffic' on its own without linking this to the router choosing a different route.

Do not accept 'different routers send the packets' on its own without a reason why a different router/route is chosen.

Do not accept an answer that only says the packets take different routes without explaining why.

Indicative content

Administrator accounts

• An administrator account can create new user accounts for new employees and delete accounts when employees leave.
• The administrator can reset a forgotten password, so an employee can get back to work without sharing another person's account.
• The administrator can set the access rights for each user or group, so designers get access to project folders and only directors can open salary files.
• Administrator privileges should be given to only a few trusted employees, as administrators can change any settings on the system.

Standard user accounts

• Designers should use standard user accounts, so they cannot install unauthorised software or change system settings.
• A standard user can be given permission to read and write files in the project folder that their team uses.
• Standard users should not be able to change other users' permissions, so the access rules cannot be removed by accident.
• If a standard user tries to open a file without permission, the operating system denies access.

File permissions

• Each file or folder can have permissions that allow a user to read, write or delete it.
• Project folders can be set so all designers can read and write the files inside them.
• Salary files can be set so only directors can read them, and other users are denied access.
• Permissions can be set for a group of users, such as all designers, which is quicker than setting them for each person.
• A file can be made read-only for standard users, so they can view it but cannot change it.

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 administrator accounts, standard user accounts and file permissions, and apply them to the design company.

Do not accept general operating system functions such as managing the processor or memory unless they are explicitly linked to controlling what a user can access.