Edexcel GCSE Computer Science (1CP2) Exam Questions

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

• The program (and its data) is copied/loaded from secondary storage into main memory/RAM (1) so that the CPU can fetch/execute its instructions (1)
• An area of main memory is allocated/reserved for the program (1) that is large enough to hold the program and its data (1)
• The operating system checks that there is enough free main memory (1) before the program can be started/loaded, otherwise it cannot run/an error is reported (1)
• The operating system keeps a record of the memory addresses used by the program (1) so that its instructions and data can be found when it runs (1)

Allow 'loaded into RAM', 'stored in memory' and 'put into main memory' as equivalent to copied into main memory.

A single statement that the program is loaded/stored in main memory, with no linked development, can be given one mark only.

Do not accept descriptions of the CPU fetching/executing instructions that do not refer to the operating system loading or allocating memory.

Do not accept responses about virtual memory (moving processes to secondary storage) or about which process runs next on the CPU.

Do not accept the program being run from secondary storage/hard disk.

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 description such as:

• Each user/file is given permissions/access rights (1) so other users cannot read/write/open/change that user's files (1)
• A user may be given read-only/read access to a file (1) so they cannot edit/delete/change it (1)
• Each file is given permissions/access rights for different users (1) so the operating system allows/refuses access depending on which user is logged in (1)
• The operating system checks a user's permissions/access rights when a file is opened (1) so a user with read-only/read access cannot save/delete changes (1)

Do not accept responses about asking for a password/username, as this checks who the user is, not what they are allowed to do.

Do not accept 'files are protected/safe' or 'access rights protect files' without saying how access is limited (e.g. read-only access, permissions for different users).

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

• It allows the operating system/OS to communicate with the device/printer (1) because it translates the commands into signals the device understands (1)
• It contains/sends the instructions/commands needed by a particular device (1) so the device carries out the correct actions (1)
• It controls the device/printer (1) by sending commands/signals to it (1)
• Different devices need different commands (1) so each one needs its own driver to work with the operating system (1)

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

Do not accept 'it drives/controls the device' on its own without saying how, e.g. by sending commands/signals.

Do not accept hardware/a physical device (a device driver is software).

Do not accept 'it connects the printer to the computer' or 'it installs the printer' without saying that it provides the instructions/commands for the device.

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.