Chapter 16

Across

3. a fixed time slice allocated to a process.
5. occurs when a requested page is not in memory and a free page cannot be used to satisfy allocation.
7. occurs when a new page is referred but is not yet in memory.
8. data structure used to implement an interrupt vector table.
10. this is a memory cache which can reduce the time taken to access a user memory location; it is part of the memory management unit.
11. problem resulting from use of virtual memory. Excessive swapping in and out of virtual memory leads to a high rate of hard disk read/write head movements thus reducing processing speed.
13. form of memory management which divides up physical memory and logical memory into fixed-size memory blocks.
14. method by which a system assigns a processor to a task or process based on the priority level.
16. term used to describe a page in memory that has been modified.
18. a small program that is used to load other programs to ‘start up’ a computer.
21. process manager which handles the removal of running programs from the CPU and the selection of new processes.
23. fixed-size logical memory blocks.
24. the core of an OS with control over process management, memory management, interrupt handling, device management and I/O operations.
28. point at which the execution of a process comes to a halt since the system is busier paging in/out of memory rather than actually executing them.
30. main/primary RAM memory.
33. table that maps logical addresses to physical addresses; it contains page number, flag status, frame address and time of entry.
34. running, ready and blocked; the states of a process requiring execution.
35. variable-size memory blocks into which logical memory is split up.
36. to constantly deprive a process of the necessary resources to carry out a task/process.
37. type of paging that gives the illusion of unlimited memory being available.
38. data structure which contains all the data needed for a process to run.

Down

1. device that allows certain hardware to access RAM independently of the CPU.
2. procedure by which, when the next process takes control of the CPU, its previous state is reinstated or restored.
4. function allowing a computer to process more than one task/process at a time.
6. page replacement algorithm in which the page which has not been used for the longest time is replaced.
9. space on HDD used in virtual memory, which saves process data.
12. values given to interrupts based on values 0 to 31.
15. the time when a process has control of the CPU.
17. fixed-size physical memory blocks.
19. function of memory management deciding which processes should be in main memory and where they should be stored.
20. scheduling algorithm that uses time slices assigned to each process in a job queue.
22. page replacement that keeps track of all pages in memory using a queue structure. The oldest page is at the front of the queue and is the first to be removed when a new page is added.
25. – type of scheduling in which a process terminates or switches from a running state to a waiting state.
26. the address space that an OS perceives to be main storage.
27. phenomenon which means it is possible to have more page faults when increasing the number of page frames. Optimal page replacement – page replacement algorithm that looks forward in time to see which frame to replace in the event of a page fault.
29. a program that has started to be executed.
30. type of scheduling in which a process switches from running state to steady state or from waiting state to steady state.
31. a form of data swapping where pages of data are not copied from HDD/SSD into RAM until they are actually required.
32. index number of a segment.
35. table containing the segment number, segment size and corresponding memory location in physical memory: it maps logical memory segments to physical memory.