Edexcel GCSE Computer Science (1CP2) Exam Questions

Award one mark for any of the following up to a maximum of two marks:

• Deciding which process runs next on the CPU/scheduling processes (1)
• Allocating processor/CPU time to processes/allowing multitasking (1)
• Managing the process life-cycle/process states (ready, running, blocked) (1)
• Handling interrupts so a running process is suspended and another can run (1)
• Stopping/terminating a process when it has finished (1)

Do not accept 'managing processes' on its own.

Do not accept 'handling interrupts' on its own.

Do not award two marks for the same task expressed twice, e.g. 'deciding which process runs next' and 'scheduling processes', or 'allocating CPU time' and 'giving each process a share of processor time'.

Do not accept 'managing memory/memory management', 'managing files/file management' or 'managing devices/peripherals' (these are other functions of an operating system).

Award one mark for any of the following up to a maximum of two marks:

• Creating/deleting user accounts (1)
• Storing usernames and passwords (1)
• Checking login details/authenticating a user at login (1)
• Setting access rights/permissions for each user, e.g. restricting which files/folders/programs/drives they can access (1)

Allow logging in as an example of checking login details.

Do not accept managing users on its own.

Do not accept provides a user interface, as this is not user management.

Do not accept managing files or managing processes, as these are other functions.

Do not accept stopping hackers/protecting from malware, as this is security, not user management.

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

• Updates/changes the location/path stored for the file (1) so the file can be found in its new folder/location (1)
• Removes the file's entry/reference from the old folder (1) so the file no longer appears/is listed there (1)
• Adds/creates an entry/reference for the file in the new folder (1) so the file appears/is listed in its new location (1)
• Updates the folder/directory listing/structure (1) to show the file's new location/path (1)

Do not accept descriptions of copying the file or leaving a duplicate in the old folder.

Do not accept deleting and recreating the file, or moving the file's data to a different physical location on the disk; the marks are for updating the folder/directory structure.

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

• The start and end address/size of the block allocated to each program is recorded (1) so the operating system knows which areas of main memory are in use and which are free (1)
• The record is checked before memory is allocated (1) so memory already in use is not given to another program/is not overwritten (1)
• The record is searched for a free block that is large enough (1) so a newly loaded program is placed in a suitable area of main memory (1)
• The record is updated when a program ends/closes (1) so the memory it was using is marked as free for other programs (1)

Allow the record to be called a memory map/memory table/allocation table.

A response that only says the operating system keeps a record/list of the memory each program is using, without saying what the record contains, earns 0 marks.

A response that states what the record contains, e.g. the addresses/the start and end address of each block, earns 1 mark even if it does not say how the record is used.

Do not accept responses about saving programs/files to secondary storage or about moving programs to virtual memory, as these are not uses of this record.

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

• A storage limit/quota is set for each user account (1) so the drive is shared fairly between users (1)
• The operating system records how much space each user's files are using (1) and refuses to save more files when the limit is reached (1)
• Each user is given a fixed share/quota of the drive (1) so one user cannot use the space set aside for another (1)

Allow a limit set by an administrator or through the operating system's user management settings; an administrator is not required for credit.

Allow a warning that stops the save; do not award the development for a warning alone where the save is not stopped.

Do not accept responses about passwords/authentication, keeping files separate/folders with no storage limit, deleting old files, compressing files, or buying a larger drive.

Do not accept 'the operating system gives the user a bigger hard drive'.

Do not accept a single global limit for all users; the limit must apply to each user/user account.

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

• Data is sent to/received from the correct peripheral (1) because the operating system controls the transfer of data between the computer and each device (1)
• A new peripheral can be used as soon as it is connected (1) because the operating system installs/loads the correct device driver for that device (1)
• Data can be sent to a slow peripheral such as a printer (1) because the operating system stores it in a buffer/print queue until the device is ready to receive it (1)
• The user is told when a peripheral has a problem (1) because the operating system receives status information from the device and reports the error to the user (1)

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

Allow specific peripherals as the example (e.g. a mouse, a printer) provided the reason says what the operating system does.

Allow 'the operating system responds to an interrupt from a device' as a point, with the reason that the device is signalling that it needs attention/has finished its job.

Do not accept 'the operating system manages/controls the peripherals' or 'it lets the devices be used'/'the peripherals work correctly' on their own, as these repeat the question without saying what the operating system does.

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

• A process is created for the program (1) so that its instructions can be loaded into RAM (1)
• The process is put into the ready state (1) so that it can wait for the CPU to become available (1)
• The operating system adds the process to a queue of ready processes (1) so the scheduler can choose it when the CPU is free (1)
• The operating system allocates the resources the process needs (1) so that it can start running when it is given CPU time (1)

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

Allow 'main memory' for RAM.

Do not accept 'the browser is downloaded/loaded from the internet'.

Do not accept 'the program is run immediately on the CPU' without the ready step.

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.