Purpose & Function of Operating Systems Exam Questions

• A File management (1)
• The only correct answer is A. The correct answer is file management.
• B is not correct because peripheral management controls input and output devices such as printers and mice
• C is not correct because process management decides which program will next run on the CPU
• D is not correct because user management handles logins, passwords and access rights

• D Process management (1)
• The only correct answer is D. The correct answer is process management.
• A is not correct because file management organises files and folders on storage
• B is not correct because memory management keeps track of where programs and data are held in RAM
• C is not correct because peripheral management sends data to and from devices such as printers

• C Peripheral management (1)
• The only correct answer is C. The correct answer is peripheral management.
• A is not correct because a device driver is a program that controls one type of peripheral device
• B is not correct because file management names, saves, moves and deletes files
• D is not correct because process management allocates time on the CPU to programs

• D User management (1)
• The only correct answer is D. The correct answer is user management.
• A is not correct because access rights are the permissions a user has to read or change files
• B is not correct because file management organises files and folders on storage
• C is not correct because the user interface is how a person interacts with the computer

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:

• Receives input from/sends output to peripheral devices (1)
• Communicates with/controls a peripheral using its device driver, including installing the driver for a new device (1)
• Manages the print queue/buffer so that print jobs are sent to the printer in turn (1)
• Reports the status of a device/a device error to the user, e.g. out of paper (1)

Allow answers that name a specific peripheral, as long as they also say what the operating system does with it, e.g. 'it controls the printer using its driver'.

Do not accept 'manages peripherals'/'controls the hardware' on its own, as this repeats the question.

Do not accept 'managing files' or 'managing users' (file management and user management 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:

• Keeps a record/index of where each file is stored on the disk (1) so that the file can be found and opened when it is needed (1)
• Allocates each file to a folder/directory (1) so that files used for the same purpose are kept together (1)
• Decides where on the disk each new file is written (1) so that it does not overwrite an existing file (1)
• Allocates space on the disk for a file (1) so that the file has somewhere to be saved (1)

Allow 'files are organised into folders so that they are easy to find', with the folder point (1) and its purpose (1).

Do not accept responses that only state that the operating system 'organises' or 'controls' the files, with no way of doing it given.

Do not accept 'stores the files' or 'saves files to the disk' without a way of doing it.

Do not accept responses about backing files up, or about the amount of storage space left on the disk.

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

• Gives each process a share/a small amount (time slice) of the CPU time (1) so that several processes can run and appear to run at the same time (1)
• Decides which process will use the CPU next, e.g. by priority (1) so that the most important process is run first (1)
• Keeps track of the state of each process (ready/running/blocked) (1) so that each process is moved to the state it needs to be in (1)
• Moves a process that is waiting for input/a resource (e.g. a printer) to blocked (1) so that another process can use the CPU (1)

Do not award a mark for stating only that the operating system runs/controls the programs.

Do not award a mark for describing multitasking in general, e.g. 'the operating system runs more than one program at once', without saying how the operating system manages the processes.

Do not accept responses about memory management (e.g. loading a program into RAM), the user interface or user management.

Accept 'processor' for CPU.

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

• Stores a username and password/user account for each user (1) so that each user must log in before they can use the computer (1)
• Stores each user's password in an encrypted form (1) so that another user cannot read it and log in as them (1)
• Sets access rights/permissions for each user (1) so that a user can only open/see their own files (1)
• Gives each user a different level of access (1) so that a system administrator can change settings that other users cannot (1)

Allow 'user accounts' as an alternative to a username and password, where a linked development is given.

Do not accept responses that only state that the operating system 'has passwords'/'has user accounts' or that 'the user logs in', with no linked development.

Do not accept responses about file management, such as creating folders or saving files, rather than user management.

Do not accept responses about keeping the computer safe from viruses, hackers or malware.

Ignore responses about the user interface.

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

• The operating system keeps a record of where each file is stored (1) so files can be found/retrieved later (1)
• The operating system keeps files in separate storage locations (1) so files are not overwritten/lost (1)
• The operating system allocates files to folders/directories (1) so it can keep track of the files stored on the disk (1)
• The operating system deletes/moves files (1) so storage space is freed/reused (1)

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

Do not accept 'it manages files'/'it organises files' without expansion as to what is managed or organised.

Do not accept 'so files are managed/organised' as the linked reason.

Do not accept 'so the computer works' as the linked reason.

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

• The operating system decides which process will use the CPU next (1) so the processor is shared between processes/processes take turns (1)
• The operating system allocates CPU time to each process/gives each process a small amount of time on the CPU (1) so multitasking can take place/several programs can appear to run at once (1)
• The operating system manages the state of each process, e.g. ready/running/blocked (1) so a process waiting for input/blocked does not stop other processes running (1)
• The operating system can terminate/end a process that has stopped responding (1) so it does not affect other processes/the computer keeps working (1)

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

Do not accept the idea that the CPU runs two or more processes at exactly the same time; multitasking shares CPU time.

Do not accept 'the OS shares the CPU' on its own without saying how/why, e.g. giving each process a turn/CPU time.

Do not accept 'it stops programs crashing' without a link to process management, e.g. ending a process that has stopped responding.

Do not accept 'it manages processes' without saying what the operating system does.

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

• The operating system uses the printer's device driver to communicate with the printer (1) so the print job is sent as commands the printer can carry out (1)
• The operating system holds print jobs in a queue/buffer (1) because the computer sends data faster than the printer can print it (1)
• The operating system reports the printer's status to the user (1) so the user knows what to do when there is a problem such as the paper running out (1)
• The operating system handles interrupts/signals from the printer (1) so a problem such as a paper jam is dealt with while other programs carry on running (1)

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

Allow a point about the operating system loading/installing the device driver for a new printer (1) provided the second mark gives a reason that is not the same as the driver communication point, e.g. so the new printer can be used/controlled by the operating system (1)

Award 1 mark for stating that print jobs are held in a queue/a buffer; the second mark needs the linked reason that the printer prints more slowly than data is sent.

Do not accept restating the question, e.g. 'it manages the printer' or 'it controls the peripherals', without saying how or why.

Do not accept 'it lets the printer connect to the computer' or 'it stops the printer being damaged' without a linked reason.

Do not accept 'it makes the printer print faster' as the operating system cannot increase the printer's speed.

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

• The operating system checks usernames/passwords at login (1) so only allowed users can access the computer (1)
• The operating system stores a list/database of users and passwords (1) so it knows who is allowed to log in (1)
• The operating system sets access rights/permissions for each user (1) so a user can only open/edit their own files (1)
• The operating system restricts programs/drives/settings by user (1) so certain users cannot change them (1)
• The operating system keeps each user's files separate (1) so one user cannot access another user's private files (1)

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

Do not accept 'so the computer is safe/secure' without saying what is protected and from whom.

Do not accept answers that say user management makes the computer faster.

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

• Naming/renaming files (1)
• Saving files (1)
• Copying files (1)
• Moving files (1)
• Deleting files (1)
• Creating folders/directories (1)
• Allocating files to folders/directories (1)
• Keeping a record/index of where each file is stored (1)
• Making sure one file does not overwrite another (1)

Allow 'indexing files' or 'keeping a directory of files' for keeping a record of where each file is stored.

Allow 'creating folders/directories' and 'allocating files to folders/directories' as separate tasks (one creates the folder, the other places a file in it).

Do not award the same task twice; do not award both 'moving files' and 'allocating files to folders/directories' when they describe the same action.

Do not accept 'managing files' or 'organising files' on its own, with no named task.

Do not accept tasks that are part of another function, e.g. 'deciding which process runs next' (process management), 'setting up user accounts and passwords' (user management).

Do not accept statements about where files are physically stored, e.g. 'on the hard disk', with no named task.

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

How the CPU is shared between processes

• The operating system uses multitasking to give each process a short time slice on the CPU, so the music, video editor and download appear to run at the same time.
• The operating system decides which ready process will run next, so one program cannot keep the CPU to itself.
• The operating system can stop a running process and move it back to ready when its time slice ends, so all processes make progress.

The states a process can be in

• When a program is opened, the operating system creates a process and moves its instructions into RAM so it is ready.
• The operating system moves a ready process to running when the CPU is free.
• A running process becomes blocked when it is waiting for input or data, such as the download waiting for data to arrive.
• When the process finishes, the operating system terminates it and releases the resources it was using.

How the operating system responds when a process needs attention

• An interrupt is a signal to the CPU that needs immediate attention, so the operating system suspends the current process and runs the interrupt handler.
• A hardware interrupt could be a printer out of paper, and a software interrupt could be an error in a program.
• After the interrupt has been handled, the operating system can return the interrupted process to the CPU.

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 at least two of scheduling, process states and interrupts.
• A response that only states that the OS 'manages processes' or gives a program a turn, without expansion, is limited to Level 1.