Micro Operating Systems Test #2

Front 1

Deadlock

Back 1

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. This problem completes when the remainder of the system comes to a standstill

Front 2

Batch

Back 2

a type of system developed for the earliest computer systems that used punch cards or tape from input.

Front 3

interactive system

Back 3

a system that allows each user to interact directly with the operating system via commands entered from a keyboard.

Front 4

real-time system

Back 4

the computing system used in time-critical enviroments that require guaranteed response times, such as navigation systems, rapid transit systems, and industrial control systems.

Front 5

Locking

Back 5

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

Front 6

Spooling

Back 6

a technique developed to speed I/O by collecting in a disk file either input received from slow input devices or output going to slow output devices such as printers.

Front 7

Mutual Exclusion

Back 7

one of four conditions for deadlock in which only one process is allowed to have access to a resource. It is typically shortened to mutex in algorithms describing synchronization between processes.

Front 8

Circular Wait

Back 8

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.

Front 9

Prevention

Back 9

a design strategy for an operating system where resources are managed in such a way that some of the necessary conditions for deadlock do not hold.

Front 10

Avoidance

Back 10

A strategy for deadlock avoidance. It is a dynamic strategy, attempting to ensure that resources are never allocated in such a way as to place a system in an unsafe state.

Front 11

Starvation

Back 11

the result of conservative allocation of resources in which a single job is prevented from execution because it is kept waiting for resources that never become available.

Front 12

Master/Slave Configuration

Back 12

an asymmetric multiprocessing configuration consisting of a single processor system connected to slave processors, each of which is managed by the primary master processor, which provides the scheduling functions and jobs.

Front 13

Loosely coupled configuration

Back 13

a multiprocessing configuration in which each processor has a copy of the operating system and controls its own resources.

Front 14

Symmetric configuration

Back 14

a multi-processing configuration in which processor scheduling is decentralized and each processor is of the same type. A single copy of the operating system and a global table listing each process and its status is stored in a common area of memory so every processor has access to it. Each processor uses the same scheduling algorithm to select which process it will run next.

Front 15

Test-and-Set

Back 15

an indivisible machine instruction known simply as TS, which is executed in a single machine cycle to determine whether the processor is available.

Front 16

Wait and Signal

Back 16

a modification of the test-and-set synchronization mechanism that is designed to remove busy waiting.

Front 17

Readers and Writers

Back 17

A problem that arises when two types of processes need to access a shared resource such as a file or a database. Their access must be controlled to preserve data integrity.

Front 18

Dedicated Devices

Back 18

a device that can be assigned to only one job at a time; it serves that job for the entire time the job is active.

Front 19

Shared Device

Back 19

a device that can be assigned to several active processes at the same time.

Front 20

Virtual Device

Back 20

a dedicated device that has been transformed into a shared device through the use of spooling techniques.

Front 21

Interrupts

Back 21

a hardware signal that suspends execution of a program and activates the execution of a special program known as the interrupt handler. It breaks the normal flow of the program being executed.

Front 22

Buffers

Back 22

the temporary storage areas residing in main memory, channels, and control units. They are used to store data read from an input device before it is needed by the processor and to store data that will be written to an output device.

Front 23

I/O Traffic Controller

Back 23

one of the modules of the I/O subsystem that monitors the status of every device, control unit, and channel.

Front 24

F.C.F.S

Back 24

the simplest scheduling algorithm for direct access storage devices that satisfies track requests in the order in which they are received.

Front 25

S.S.T.F

Back 25

a scheduling strategy for direct access storage devices that is used to optimize seek time. The track requests are ordered so the one closest to the currently active track is satisfied first and the ones farthest away are made to wait.

Front 26

SCAN

Back 26

a scheduling strategy for direct access storage devices that is used to optimize seek time.

Front 27

C-SCAN

Back 27

a scheduling strategy for direct access storage devices that is used to optimize seek time.

Front 28

Field

Back 28

A group of related bytes that can be identified by the user with a name, type, and size.

Front 29

File

Back 29

a group of related records that contains information to be used by specific application programs to generate reports.

Front 30

Database

Back 30

a group of related files that are interconnected at various levels to give users flexibility of access to the data stored.

Front 31

Directory

Back 31

a logical storage unit that contains files.

Front 32

Volume

Back 32

any secondary storage unit, such as hard disks, or tapes.

Front 33

Sub-Directory

Back 33

a directory created by the user within the boundaries of an existing directory. Some operating systems call this a folder.

Front 34

Non-Contiguous Storage

Back 34

a type of file storage in which the information is stored in nonadjacent locations in a storage medium. Data records can be accessed directly by computing their relative addresses.

Front 35

Data Compression

Back 35

a procedure used to reduce the amount of space required to store data by reducing encoding or abbreviating repetitive terms or characters.

Front 36

Device Allocation Deadlock

Back 36

The use of a group of dedicated devices, such as a cluster of DVD read/write drives, can also deadlock the system.

Front 37

Network Deadlocks

Back 37

A congested network that has filled a large percentage of its I/O buffer space can become deadlocked if it doesn't have protocols to control the flow of messages through the network.

Front 38

Disk Sharing Deadlock

Back 38

An active type of deadlock known as a live-lock in which the ability to share a disk causes programs to never reach fulfillment.

Front 39

4 conditions for Deadlock

Back 39

mutual exclusion
resource holding
no pre-emption
circular wait

Front 40

Deadlock Victim

Back 40

an expendable job that is selected for removal from a deadlocked system to provide more resources to the waiting jobs and resolve the deadlock.

Front 41

Parallel Processing

Back 41

the process of operating two or more CPU's in parallel that is more than one CPU executing instructions simultaneously.

Front 42

Multi Processing

Back 42

when two or more CPUs share the same main memory, most I/O devices, and the same control program routines. They service the same job stream and execute distinct processing programs concurrently.

Front 43

Process Manager

Back 43

a composite of two submanagers, the job scheduler and the process scheduler. It decides how to allocate the cpu, monitors whether it is executing a process or waiting, and controls job entry to ensure balanced use of resources.

Front 44

Role of Master Processor in a Master/Slave configuration

Back 44

it maintains the status of all processes in the system performs storage management activities, schedules the work for the other processors, and executes all control programs.

Front 45

Advantages of the Master/Slave configuration.

Back 45

This configuration is well suited for computing environments in which processing time is divided between front-end and back-end processors

Front 46

Disadvantages of the Master/Slave configuration.

Back 46

- if the master fails, the entire system fails
- can lead to poor use of resources.
- increases the number of interrupts

Front 47

Producers and Consumers

Back 47

a classic problem in which a process produces data that will be consumed, or used, by another process. It exhibits the need for process cooperation.

Front 48

States of Threads

Back 48

1 Creation
2 Ready
3 Waiting
4 Delayed
5 Blocked
6 Running
7 Finished

Front 49

USB Controller

Back 49

acts as an interface between the operating system, device drivers, and applications and the devices that are attached via the USB host.

Front 50

Transfer Rate

Back 50

? = density of the tape X transport speed

Front 51

Direct Access Storage Devices

Back 51

devices that can read or write to a specific place. IE. magnetic disks, optical discs, and flash memory

Front 52

Fixed Head

Back 52

Much faster than movable head, disadvantage is the high cost and reduced storage space.

Front 53

Movable Head

Back 53

magnetic disks, such as computer hard drives, that have one read/write head that floats over each surface of each disk.

Front 54

Cylinder

Back 54

for a disk or disk pack it is when two or more read/write heads are positioned at the same track, at the same relative position, on their respective surfaces.

Front 55

Pit

Back 55

An indentation burnt onto the disc that represents a 0

Front 56

Lands

Back 56

Flat surfaces on an optical disc that represent 1's

Front 57

Flash Memory

Back 57

a nonvolatile removable medium that emulates random access memory, but unlike RAM, stores data securely even when it's removed from it power source.

Front 58

Movable Head Access Times

Back 58

Seek time (arm movement) +
search time (rotational delay) +
transfer time (data transfer) =
access time

Front 59

Fixed Head Access Times

Back 59

search time +
transfer time =
Access time

Front 60

RAID 0

Back 60

well suited to transferring large quantities of non-critical data. No error correction methods, excellent I/O request rate, Excellent Data transfer rate.

Front 61

RAID 1

Back 61

provides redundancy by having a duplicate set of all data in a mirror array of disks, which act as a backup system in the event of hardware failure.

Front 62

RAID 5

Back 62

Parity strips are distributed across all disks alleviating the bottleneck created in RAID 4. however regenerating data from a failed drive is far more complicated.

Front 63

RAID 6

Back 63

raid configuration that writes two parity strips for an extra degree of protection. However read/write functions are slower as a result.

Front 64

File Manager

Back 64

The software responsible for creating, deleting, modifying, and controlling access to files--as well as for managing the resources used by the files.

Front 65

File manager responsibilities

Back 65

1. Keep track of where each file is stored
2. Use a policy that will determine where and how the files will be stored making sure to efficiently use the available storage space and provide efficient acces to the files.
3. Allocate each file when a user has been cleared for access to it, then record its use.
4. Deallocate the file when the file is to be returned to storage, and communicate its availability to others who may be waiting for it.

Front 66

Master File Directory

Back 66

this is stored immediately after the volume descriptor and lists the names and characteristics of every file contained in that volume.

Front 67

Volume Descriptor on DVD

Back 67

an easy to access place on each unit; the innermost part of the CD or DVD, the beginning of the tape or the first sector of the outermost track of the disk pack. Once identified, the operating system can interact with the storage unit.

Front 68

File extensions

Back 68

a 3 digit extension at the end of a files name used to identify the type of files and their contents.

Front 69

Sub directory

Back 69

also known as a current directory or a working directory. This is the directory that the user is currently working in.

Front 70

Types of File Storage

Back 70

Files are usually declared to be either sequential or direct when they're created, so the file manager can select the most efficient method of storage allocation; contiguous for direct files and non-contiguouis for sequential.

Front 71

File Management and the Device Driver

Back 71

Each level of the file management system is implemented using structured heirarchy passing modules down to the lowest level where they interact with the device intended for use with the file.

Front 72

Data Compression

Back 72

These algorithms consist of two types; lossless algorithms typically used for text or arithmetic files, which retain all the data in the file throughout the compression-decompression process; and lossy algorithms, which are typically used for image and sound files and remove data permanently.