Key Terms

Question 1

the process of changing the address of an instruction or data item to the address in main memory at which it is to be loaded or relocated.

Answer 1

address resolution

Question 2

the name given to several registers, allocated to each active process

Answer 2

associative memory

Question 3

a small, fast memory used to hold selected data and to provide faster access than would otherwise be possible

Answer 3

cache memory

Question 4

the elapsed time between two ticks of the computer’s system clock

Answer 4

clock cycle

Question 5

a variation of the LRU policy that removes from main memory the pages that show the least amount of activity during recent clock cycles

Answer 5

clock page replacement policy

Question 6

a memory allocation scheme that loads a program’s page into memory at the time it is needed for processing

Answer 6

demand paging

Question 7

in a paged or segmented memory allocation environment, the difference between a page’s relative address and the actual machine language address. Also called offset

Answer 7

displacement

Question 8

an unusual circumstance through which adding more page frames causes an increase in page interrupts when using a FIFO page replacement policy

Answer 8

FIFO anomaly

Question 9

a page replacement policy that removes from main memory the pages that were brought in first

Answer 9

first-in first-out (FIFO) policy

Question 10

a table in main memory that contains two values for each active job— the size of the job and the memory location where its page map table is stored

Answer 10

Job Table (JT)

Question 11

a page-replacement policy that removes from main memory the pages that show the least amount of recent activity

Answer 11

least recently used (LRU) policy

Question 12

behavior observed in many executing programs in which memory locations recently referenced, and those near them, are likely to be referenced in the near future

Answer 12

locality of reference

Question 13

a table in main memory that contains as many entries as there are page frames and lists the location and free/busy status for each one

Answer 13

Memory Map Table (MMT)

Question 14

see displacement

Answer 14

offset

Question 15

a fixed-size section of a user’s job that corresponds in size to page frames in main memory

Answer 15

page

Question 16

a type of hardware interrupt caused by a reference to a page not residing in memory

Answer 16

page fault

Question 17

the part of the Memory Manager that determines if there are empty page frames in memory so that the requested page can be immediately copied from secondary storage, or determines which page must be swapped out if all page frames are busy. Also known as a page interrupt handler

Answer 17

page fault handler

Question 18

an individual section of main memory of uniform size into which a single page may be loaded without causing external fragmentation

Answer 18

page frame

Question 19

a table in main memory with the vital information for each page including the page number and its corresponding page frame memory address.

Answer 19

Page Map Table (PMT)

Question 20

an algorithm used by virtual memory systems to decide which page or segment to remove from main memory when a page frame is needed and memory is full.

Answer 20

page replacement policy

Question 21

the process of moving a page out of main memory and into secondary storage so another page can be moved into memory in its place

Answer 21

page swapping

Question 22

a memory allocation scheme based on the concept of dividing a user’s job into sections of equal size to allow for noncontiguous program storage during execution

Answer 22

paged memory allocation

Question 23

code that can be used by two or more processes at the same time; each shares the same copy of the executable code but has separate data areas

Answer 23

reentrant code

Question 24

a division in a disk’s track, sometimes called a “block.”

Answer 24

sector

Question 25

a variable-size section of a user’s job that contains a logical grouping of code

Answer 25

segment

Question 26

a table in main memory with the vital information for each segment including the segment number and its corresponding memory address.

Answer 26

Segment Map Table (SMT)

Question 27

a memory allocation scheme based on the concept of dividing a user’s job into logical groupings of code and loading them into memory as needed to minimize fragmentation.

Answer 27

segmented/demand paged memory allocation

Question 28

a memory allocation scheme based on the concept of dividing a user’s job into logical groupings of code to allow for noncontiguous program storage during execution

Answer 28

segmented memory allocation

Question 29

also called a “subprogram,” a segment of a program that can perform a specific function

Answer 29

subroutine

Question 30

a phenomenon in a virtual memory system where an excessive amount of page swapping back and forth between main memory and secondary storage results in higher overhead and little useful work

Answer 30

thrashing

Question 31

a technique that allows programs to be executed even though they are not stored entirely in memory

Answer 31

virtual memory

Question 32

a collection of pages to be kept in main memory for each active process in a virtual memory environment

Answer 32

working set

Question 33

a policy used to ensure that jobs that have been in the system for a long time in the lower-level queues will eventually complete their execution

Answer 33

aging

Question 34

the acts of saving a job’s processing information in its PCB so the job can be swapped out of memory and of loading the processing information from the PCB of another job into the appropriate registers so the CPU can process it. occurs in all preemptive policies

Answer 34

context switching

Question 35

a job that will perform a great deal of nonstop processing before issuing an interrupt

Answer 35

CPU-bound

Question 36

a nonpreemptive process scheduling policy (or algorithm) that handles jobs according to their arrival time

Answer 36

first-come, first-served (FCFS)

Question 37

a synonym for the Job Scheduler

Answer 37

high-level scheduler

Question 38

a job that requires a large number of input/output operations, resulting in too much free time for the CPU

Answer 38

I/O-bound

Question 39

signifies that a job’s execution is delayed indefinitely because it is repeatedly preempted so other jobs can be processed

Answer 39

indefinite postponement

Question 40

a hardware signal that suspends execution of a program and activates the execution of a special program known as the interrupt handler

Answer 40

interrupt

Question 41

the program that controls what action should be taken by the operating system when a sequence of events is interrupted

Answer 41

interrupt handler

Question 42

the high-level scheduler of the Processor Manager that selects jobs from a queue of incoming jobs based on each job’s characteristics

Answer 42

Job Scheduler

Question 43

the condition of a job as it moves through the system from the beginning to the end of its execution

Answer 43

job status

Question 44

a synonym for the Process Scheduler

Answer 44

low-level scheduler

Question 45

a scheduler used by the Processor Manager when the system to remove active processes from memory becomes overloaded

Answer 45

middle-level scheduler

Question 46

a process scheduling scheme (used with other scheduling algorithms) that groups jobs according to a common characteristic.

Answer 46

multiple-level queues

Question 47

a technique that allows a single processor to process several programs residing simultaneously in main memory and interleaving their execution by overlapping I/O requests with CPU requests

Answer 47

multiprogramming

Question 48

a common term used to identify an I/O request from a program in a multiprogramming environment that would cause a process to wait “naturally” before resuming execution.

Answer 48

natural wait

Question 49

a job scheduling strategy that functions without external interrupts so that once a job captures the processor and begins execution, it remains in the running state uninterrupted until it issues an I/O request or it’s finished.

Answer 49

nonpreemptive scheduling policy

Question 50

any process scheduling strategy that, based on predetermined policies, interrupts the processing of a job and transfers the CPU to another job. It is widely used in time-sharing environments

Answer 50

preemptive scheduling policy

Question 51

a nonpreemptive process scheduling policy (or algorithm) that allows for the execution of high-priority jobs before low-priority jobs

Answer 51

priority scheduling

Question 52

an instance of execution of a program that is identifiable and controllable by the operating system

Answer 52

process

Question 53

a data structure that contains information about the current status and characteristics of a process

Answer 53

Process Control Block (PCB)

Question 54

the low-level scheduler of the Processor Manager that establishes the order in which processes in the READY queue will be served by the CPU

Answer 54

Process Scheduler

Question 55

an algorithm used by the Job Scheduler to allocate the CPU and move jobs through the system

Answer 55

process scheduling algorithm

Question 56

any policy used by the Processor Manager to select the order in which incoming jobs will be executed

Answer 56

process scheduling policy

Question 57

information stored in the job’s PCB that indicates the current position of the job and the resources responsible for that status

Answer 57

process status

Question 58

(1) a synonym for the CPU, or (2) any component in a computing system capable of performing a sequence of activities

Answer 58

processor

Question 59

an interactive unit, such as a file stored on a disk

Answer 59

program

Question 60

a linked list of PCBs that indicates the order in which jobs or processes will be serviced

Answer 60

queue

Question 61

a measure of the efficiency of an interactive system that tracks the speed with which the system will respond to a user’s command

Answer 61

response time

Question 62

a preemptive process scheduling policy (or algorithm) that allocates to each job one unit of processing time per turn to ensure that the CPU is equally shared among all active processes and isn’t monopolized by any one job

Answer 62

round robin

Question 63

a nonpreemptive process scheduling policy (or algorithm) that selects the waiting job with the shortest CPU cycle time

Answer 63

shortest job next (SJN)

Question 64

a preemptive process scheduling policy (or algorithm) similar to the SJN algorithm that allocates the processor to the job closest to completion

Answer 64

shortest remaining time (SRT)

Question 65

(1) the term used to describe a process, or (2) the basic unit of concurrent programming languages that defines a sequence of instructions that may be executed in parallel with other similar units

Answer 65

task

Question 66

a portion of a program that can run independently of other portions

Answer 66

thread

Question 67

a period of time assigned to a process for execution before it is preempted

Answer 67

time quantum

Question 68

a measure of a system’s efficiency that tracks the time required to execute a job and return output to the user

Answer 68

turnaround time

Question 69

the dynamic strategy of deadlock avoidance that attempts to ensure that resources are never allocated in such a way as to place a system in an unsafe state.

Answer 69

avoidance

Question 70

one of four conditions for deadlock through which each process involved is waiting for a resource being held by another; each process is blocked and can’t continue, resulting in deadlock.

Answer 70

circular wait

Question 71

a problem occurring when the resources needed by some jobs to finish execution are held by other jobs, which, in turn, are waiting for other resources to become available. Also called deadly embrace.

Answer 71

deadlock

Question 72

the process of examining the state of an operating system to determine whether a deadlock exists.

Answer 72

detection

Question 73

a graphic model representing various states of resource allocations.

Answer 73

directed graphs

Question 74

a locked system whereby two (or more) processes continually block the forward progress of the others without making any forward progress themselves. It is similar to a deadlock except that neither process is blocked or obviously waiting; both are in a continuous state of change.

Answer 74

livelock

Question 75

a technique used to guarantee the integrity of the data in a database through which the user locks out all other users while working with the database.

Answer 75

locking

Question 76

one of four conditions for deadlock in which only one process is allowed to have access to a resource.

Answer 76

mutual exclusion

Question 77

one of four conditions for deadlock in which a process is allowed to hold on to resources while it is waiting for other resources to finish execution.

Answer 77

no preemption