Memory Management Exam Questions

• C Process management (1)
• The only correct answer is C. The correct answer is process management; memory management is part of process management.
• A is not correct because file management organises and stores files and folders, not main memory allocation
• B is not correct because peripheral management controls devices such as printers and keyboards
• D is not correct because user management controls user accounts and access

• B Main memory (1)
• The only correct answer is B. The correct answer is Main memory.
• A is not correct because the cache is small, fast memory in the CPU that holds frequently used instructions and data
• C is not correct because registers are small storage locations in the CPU that hold the data being worked on
• D is not correct because secondary storage is where the game is stored and copied from, not where it is copied into

• A It chooses an area of main memory that is not being used by another process (1)
• The only correct answer is A. The correct answer is choosing an area of main memory that is not being used by another process.
• B is not correct because the operating system keeps its own area of main memory and does not give it to a process
• C is not correct because the number of files a process can open is part of file management, not memory management
• D is not correct because user management controls who can log on and what each user is allowed to access

• C To make sure existing programs and data are not overwritten (1)
• The only correct answer is C. The correct answer is to make sure existing programs and data are not overwritten.
• A is not correct because deciding which process runs next and for how long is not why the locations of programs in memory are recorded
• B is not correct because a program is only moved to secondary storage when virtual memory is used
• D is not correct because multi-tasking lets more than one process use the CPU in turn

Award one mark for:

• Copies/loads the program (and the data it uses) from secondary storage/the hard disk into main memory/RAM (1)

Allow 'the program is moved into RAM'.

Do not accept 'installs the program'.

Do not accept 'opens the program' or 'runs the program' on their own.

Award one mark for any of the following:

• It frees/releases the memory (1)
• The memory is marked as available/empty so that another program can use it (1)
• The program and its data are removed/deleted from main memory (1)

Allow 'the memory is cleared'.

Do not accept 'it deletes the program from the hard disk' (the program is stored in secondary storage and is not removed).

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

• So that it does not overwrite/use memory that is already being used by another program (1)
• So that it can find the program/data again when the program needs it (1)
• So that it knows which memory locations are free/can be allocated to a new program (1)
• So that it can keep the data used by each program separate from other programs (1)
• So that it can free the memory when the program is closed/knows which memory to release (1)

Do not accept 'so the program runs faster'.

Do not accept 'so that the program is not lost when the power is turned off' (this is about saving files to secondary storage, not main memory).

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

• Decides which program/process will run on the CPU next (1)
• Decides how long each program/process will run for/gives each process a time slice (1)
• Allocates/shares out main memory between the programs/processes (1)
• Moves a program (and its data) that is not currently being used from main memory to virtual memory/secondary storage, and back when needed (1)
• Stores/saves the state of each process so that it can continue where it left off (1)

Do not accept 'it makes the computer faster'.

Do not accept 'it runs all of the programs at exactly the same time' on a single CPU.

Do not accept the name of a scheduling algorithm on its own (e.g. round robin) without a description.

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:

• 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:

• The memory (that was) used by the program is freed/released/marked as free (1) so it can be allocated/reused by another program/process (1)
• The operating system's memory allocation table/record (of memory in use) is updated (1) to show that the program's memory locations/blocks are now free/available (1)
• The program's instructions/data are removed/overwritten in main memory (1) so the space they used is no longer reserved for that program (1)
• The memory pages/blocks allocated to the program are returned to the list of free pages/blocks (1) that can be used when the next program is loaded (1)

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

Do not award two marks for the same idea described twice (e.g. the memory is freed and added to a list of free blocks); the two marks must come from two different linked descriptions.

Do not accept responses about closing the program window, stopping/terminating the program/process, saving the file or deleting the program from secondary storage/the hard disk.

Ignore statements that main memory is 'managed'/'cleaned up' with no development.

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:

• The CPU can only fetch/execute instructions held in main memory (1) because it cannot access secondary storage directly (1)
• The program's instructions are copied into RAM/main memory (1) so the CPU can read/fetch them (1)
• Main memory is faster to access than secondary storage (1) so the CPU does not have to wait for the program's instructions to be read from secondary storage (1)
• The program's data is copied into main memory (1) so the CPU can access it directly while the program runs (1)

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

A statement of location on its own, e.g. 'the program needs to be in RAM' / 'the program is copied into main memory', earns the first mark only; a reason linked to the CPU fetching or accessing it is needed for the second mark.

Do not accept 'so the program can run', 'so the program can be loaded/started' or 'so it is in memory' on its own without saying that the CPU can access/fetch it from main memory.

Do not accept 'quickly' on its own as the reason; accept it only when linked to the CPU accessing the data/instructions directly or faster than secondary storage.

Do not accept 'to store the program permanently', 'to save the program' or 'so it is not lost when the computer is switched off' as main memory is volatile.

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

• So the operating system does not allocate memory already in use/avoids allocating the same memory to another program/prevents memory being reallocated (1) which would overwrite/corrupt the existing program or data (1)
• So the operating system can find/locate a program or its data when it is needed (1) because it can then load/access it using the memory address(es) in the record (1)
• So the operating system can identify free areas of main memory (1) and allocate them to a new program/process (1)
• So the operating system can keep programs and data separate in main memory (1) so one program cannot change/overwrite another program's data (1)

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

Do not accept 'to manage memory' or 'to organise memory' on its own without saying what the record is used for.

Do not accept 'to keep track of programs' or 'so it knows where programs are' on its own: this states what the record contains, not a use for it. It needs a linked use such as finding/loading a program when needed or avoiding overwriting it.

Do not accept 'to store the program' because the record stores the location, not the program.

Do not accept answers about saving a program to secondary storage/hard disk when it is closed; the record is of locations in main memory.

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

• The operating system allocates a separate area of main memory to each program (1) so one program cannot overwrite another program's instructions/data (1)
• The operating system keeps each program in its own area of main memory (1) so a program cannot access/corrupt another program's data (1)
• The operating system keeps track of which areas of main memory are free/in use (1) so it can give memory to a program when it starts without overwriting another program (1)
• The operating system sets aside/allocates memory for a program when it is loaded (1) so that the program has space for its instructions and data (1)

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

Only one linked point is needed for both marks; a second explanation of the same idea gains no further credit.

Do not accept 'the operating system manages/shares out main memory' on its own, because this repeats the question and does not say how memory is managed.

Do not accept 'it decides which program runs next on the CPU' because this is process scheduling, not memory management.

Do not accept 'it stops programs using too much memory' or 'it makes the computer faster' without a linked reason saying how memory is managed.

Do not accept 'each program is given its own memory addresses' on its own; the point must say the program is kept in a separate area of memory.

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

• The memory can be reused/allocated to another program (1) so other programs have enough main memory to run (1)
• Freeing the memory stops main memory becoming full (1) so the computer can load/run new programs (1)
• The closed program's data is no longer needed (1) so keeping it would waste main memory (1)
• The operating system can give the freed memory to a program that needs more (1) so that program can continue to run (1)

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

Do not accept 'to make the computer faster' on its own without saying how freeing memory helps.

Do not accept 'to delete the program' or 'to save the program' because closing a program does not remove it from secondary storage.