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Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall 11

Computers:Computers:

Tools for an Information AgeTools for an Information Age

Chapter 3Chapter 3Operating Systems: Software in the BackgroundOperating Systems: Software in the Background

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22Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

ObjectivesObjectives

Describe the functions of an operating systemDescribe the functions of an operating system

Explain the basics of a personal computerExplain the basics of a personal computer

operating systemoperating system

Describe the advantages of a graphicalDescribe the advantages of a graphical

operating systemoperating system

Differentiate among different versions ofDifferentiate among different versions of

Microsoft WindowsMicrosoft WindowsExplain the need for network operating systemsExplain the need for network operating systems

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33Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

ObjectivesObjectives

Describe the methods of resourceDescribe the methods of resourceallocation on large computersallocation on large computers

Describe the differences amongDescribe the differences amongmultiprocessing, multiprogramming, andmultiprocessing, multiprogramming, andtimetime--sharingsharing

Explain the principles of memoryExplain the principles of memory

managementmanagementList several functions that are typicallyList several functions that are typicallyperformed by utility programsperformed by utility programs

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44Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Operating Systems: Hidden SoftwareOperating Systems: Hidden Software

Serves as intermediary between hardwareServes as intermediary between hardware

and applications softwareand applications software

Operating SystemOperating SystemSystems softwareSystems software

KernelKernel

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55Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Operating SystemOperating System

A set of programs that liesA set of programs that lies

between applications softwarebetween applications software

and the hardwareand the hardware

Manages computers resourcesManages computers resources(CPU, peripheral devices)(CPU, peripheral devices)

Establishes a user interfaceEstablishes a user interface

Determines how user interacts withDetermines how user interacts with

operating systemoperating system Provides and executes servicesProvides and executes services

for applications softwarefor applications software

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66Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Systems SoftwareSystems Software

All programs related to coordinatingAll programs related to coordinating

computer operationscomputer operations

ExamplesExamples Operating systemsOperating systems

Language translatorsLanguage translators

Convert program code to machineConvert program code to machine--readable formreadable form

Utility programsUtility programs

Perform secondary choresPerform secondary chores

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77Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

KernelKernel

Manages the operating systemManages the operating system

Loaded from hard drive into memory whenLoaded from hard drive into memory when

computer is bootedcomputer is booted

BootingBootingrefers to starting the computerrefers to starting the computer

Loads other operating system programs fromLoads other operating system programs from

disk storage as neededdisk storage as needed

Other programs referred to asOther programs referred to as nonresidentnonresident

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88Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Operating Systems for PersonalOperating Systems for Personal

ComputersComputersPlatform: combination of computer hardwarePlatform: combination of computer hardware

and operating system softwareand operating system software

WintelWintel(Microsoft Windows running on an Intel(Microsoft Windows running on an Intel--basedbased

PC) is most commonPC) is most common

Common PlatformsCommon Platforms

MSMS--DOSDOS

WindowsWindows

MAC OSMAC OS

UnixUnix

LinuxLinux

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99Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

MSMS--DOSDOS

Uses a commandUses a command--line interfaceline interface

Screen provides prompts for userScreen provides prompts for user

User types commandsUser types commands

Largely replaced by graphical user interfacesLargely replaced by graphical user interfaces

Not userNot user--friendlyfriendly

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1010Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Microsoft WindowsMicrosoft Windows

Began as anBegan as an operating environmentoperating environment for MSfor MS--

DOSDOS

Not a fullNot a full--blown operating system; required MSblown operating system; required MS--

DOSDOS

Uses aUses a graphical user interfacegraphical user interface

Users can use DOS commands and interfaceUsers can use DOS commands and interface

Now aNow a complete familycomplete family of operating systemsof operating systems

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1111Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

MSMS--DOS Operating EnvironmentDOS Operating Environment

Windows 3.1Windows 3.1

A layer added on top of DOSA layer added on top of DOS

Separates operating system from userSeparates operating system from user Makes operating system easier to useMakes operating system easier to use

Called aCalled a shellshell

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1212Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Graphical User InterfaceGraphical User Interface

User clicks an icon toUser clicks an icon to

perform tasksperform tasks

Start Menu in lowerStart Menu in lower

left corner launchesleft corner launchesprogramsprograms

Use menus toUse menus to

activate commandsactivate commands

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1313Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Windows FeaturesWindows Features

Long file names (up to 255 characters)Long file names (up to 255 characters)

Plug and PlayPlug and Play

Makes installing hardware components easierMakes installing hardware components easierObject Linking and Embedding (OLE)Object Linking and Embedding (OLE)

Allows user to embed or link one document toAllows user to embed or link one document to

anotheranother

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1414Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Windows 9xWindows 9x Windows 95Windows 95 Windows 98Windows 98 Windows Millennium Edition (ME)Windows Millennium Edition (ME)

Corporate MarketCorporate Market Windows NTWindows NT Windows 2000Windows 2000

Windows XPWindows XP

Windows CEWindows CE

The Windows FamilyThe Windows Family

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1515Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Windows 9Windows 9xx

Serves home/consumer marketServes home/consumer market

No longer a shell, but a selfNo longer a shell, but a self--containedcontained

operating systemoperating systemBegan with Windows 95Began with Windows 95

Next Generation:Next Generation:

Windows 98Windows 98

Windows MEWindows ME

ManyMany improvementsimprovements over Windows 3.1over Windows 3.1

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1616Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Windows 98 EnhancementsWindows 98 Enhancements

Internet/intranet browsingInternet/intranet browsing

capabilitiescapabilities

Support for stateSupport for state--ofof--thethe--artart

hardware, including DVD andhardware, including DVD and

multimediamultimedia

Support for huge disk drivesSupport for huge disk drives

Wizards: stepWizards: step--byby--step softwarestep software

for installing, configuring, andfor installing, configuring, and

using softwareusing software

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1717Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Windows ME EnhancementsWindows ME Enhancements

Multimedia support: Media Player, videoMultimedia support: Media Player, video

editingediting

Enhanced reliability featuresEnhanced reliability featuresHome network supportHome network support

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1818Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Corporate MarketCorporate Market

Windows NTWindows NT

NT stands for new technologyNT stands for new technology

Windows 2000Windows 2000

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1919Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Windows NTWindows NT

Desktop looks and acts like Windows 98Desktop looks and acts like Windows 98

Meant for corporate, networkedMeant for corporate, networked

environmentsenvironments Engineered for scalability (the ability to handleEngineered for scalability (the ability to handle

many users)many users)

Stronger securityStronger security

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2020Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Windows 2000Windows 2000

The latest generation of Windows NTThe latest generation of Windows NT

One computer serves many usersOne computer serves many users

You identify yourself and the system knowsYou identify yourself and the system knowsyour preferencesyour preferences

You get your desktop and files, regardless ofYou get your desktop and files, regardless of

which PC you use to log into the networkwhich PC you use to log into the network

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2121Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Windows XPWindows XP

Brings consumer andBrings consumer and

corporate versions ofcorporate versions of

Windows together into aWindows together into a

single productsingle product Has Home andHas Home and

Professional EditionsProfessional Editions

EnhancementsEnhancements

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2222Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Windows XP EnhancementsWindows XP Enhancements

Improved user interfaceImproved user interface Much clearer and uncluttered desktopMuch clearer and uncluttered desktop

More icons on redesigned Start MenuMore icons on redesigned Start Menu

Improved multimedia supportImproved multimedia supportMore personalizationMore personalization

Multiple user supportMultiple user support User can log off, leaving programs running, and allowUser can log off, leaving programs running, and allow

another user to log onanother user to log on

Set up limited accounts for children to use; i.e., noSet up limited accounts for children to use; i.e., noinappropriate games or no Internet accessinappropriate games or no Internet access

Internet support and protectionInternet support and protection

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2323Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Windows CEWindows CE

ScaledScaled--back version of Windows 9xback version of Windows 9x

Designed to work on machines with smallDesigned to work on machines with small

screens and little, if any, storagescreens and little, if any, storage

Used in Pocket PCsUsed in Pocket PCs

Used in embedded systemsUsed in embedded systems

Computer devices integrated into otherComputer devices integrated into other

products; i.e., robotsproducts; i.e., robots

CE.NET supports .NET platformCE.NET supports .NET platform

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2424Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

MAC OSMAC OS

Designed for theDesigned for the

Macintosh computerMacintosh computer

First commerciallyFirst commercially

successful GUIsuccessful GUI Has served as the modelHas served as the model

for Windows and otherfor Windows and other

GUI products developedGUI products developed

since thensince then

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2525Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

UNIXUNIX

Developed in 1971 for use on the DECDeveloped in 1971 for use on the DECminicomputerminicomputer

CharacterCharacter--based system with commandbased system with command--lineline

interfaceinterfaceNot tied to any family of processorsNot tied to any family of processors Runs on just about every type of system (PC,Runs on just about every type of system (PC,

mainframe, workstation) from any manufacturermainframe, workstation) from any manufacturer

Primary operating system in use on InternetPrimary operating system in use on Internetserversservers Handles many simultaneous users easilyHandles many simultaneous users easily

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2727Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Operating Systems for NetworksOperating Systems for Networks

Network operating system (NOS)Network operating system (NOS)

HandlesHandles network functionsnetwork functions

Make resources appear as though they wereMake resources appear as though they wererunning from client computersrunning from client computers

Common systemsCommon systems

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2828Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Network FunctionsNetwork Functions

Sharing resources (hard disks andSharing resources (hard disks and

printers)printers)

Data securityData securityTroubleshootingTroubleshooting

Administrative controlAdministrative control

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2929Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Network Operating SystemsNetwork Operating Systems

Windows NT ServerWindows NT Server

Windows 2000 ServerWindows 2000 Server

Windows .NET ServerWindows .NET ServerNovell NetwareNovell Netware

UnixUnix

LinuxLinux

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3030Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Operating Systems for LargeOperating Systems for Large

ComputersComputers

Resource allocation: assigning andResource allocation: assigning and

computer resources to certain programscomputer resources to certain programs

and processes for their useand processes for their use

Main issues related to resource allocationMain issues related to resource allocation

Sharing the Central Processing UnitSharing the Central Processing Unit

Sharing memorySharing memory

Sharing storage resourcesSharing storage resources

Sharing printing resourcesSharing printing resources

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3131Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Sharing the CPUSharing the CPU

MultiprocessingMultiprocessing

MultiprogrammingMultiprogramming

TimeTime--SharingSharing

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3232Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

MultiprocessingMultiprocessing

The use of a powerful computer withThe use of a powerful computer with

multiple CPUsmultiple CPUs

Multiple programs run simultaneouslyMultiple programs run simultaneously Each runs on its own processorEach runs on its own processor

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3333Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

MultiprogrammingMultiprogramming

Two or more programs executedTwo or more programs executedconcurrentlyconcurrently

Programs take turns using the CPUPrograms take turns using the CPU

EventEvent--drivendrivenAn interrupt suspends processing to allow anotherAn interrupt suspends processing to allow anotherprogram to runprogram to run

After the second program runs, the operatingAfter the second program runs, the operating

system returns the CPU to another programsystem returns the CPU to another programGenerally used for batch programs that doGenerally used for batch programs that donot require user inputnot require user input

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3434Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

TimeTime--SharingSharing

Programs take turns using the CPUPrograms take turns using the CPU

TimeTime--drivendriven

Each user is given a slice of time (fraction of a second)Each user is given a slice of time (fraction of a second)

CPU works only on that users tasks during its timeCPU works only on that users tasks during its time

sliceslice

Response time: the time between typed request andResponse time: the time between typed request and

computers replycomputers reply

Typically used in applications with many usersTypically used in applications with many users

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3535Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Sharing MemorySharing Memory

Memory managementMemory management

Divides memoryDivides memory into foreground andinto foreground and

backgroundbackgroundUses virtual storageUses virtual storage

Also called virtual memoryAlso called virtual memory

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3636Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Memory ManagementMemory Management

Divides memory into separate partitionsDivides memory into separate partitions

Allocates memory to programsAllocates memory to programs

Keeps programs separate from oneKeeps programs separate from oneanotheranother

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3737Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Foreground and BackgroundForeground and Background

Foreground: for programs with high priorityForeground: for programs with high priority

that will receive more CPU time.that will receive more CPU time.

Background: for programs with lowerBackground: for programs with lowerpriority that will receive less CPU timepriority that will receive less CPU time

Programs waiting to run are kept inPrograms waiting to run are kept in queuesqueues

based on their prioritybased on their priority

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3838Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Virtual StorageVirtual Storage

Programs currently executed are stored on diskPrograms currently executed are stored on disk

Portions of program brought into memory as neededPortions of program brought into memory as needed

Minimizes the amount of memory neededMinimizes the amount of memory needed

Can be implemented byCan be implemented by pagingpaging Divide memory into small, fixedDivide memory into small, fixed--size pagessize pages

Page table keeps track of memory locationsPage table keeps track of memory locations

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3939Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Sharing Storage ResourcesSharing Storage Resources

Keeps track of location of filesKeeps track of location of files

Responds to commands to manipulateResponds to commands to manipulate

filesfilesKeeps track of input and output requestsKeeps track of input and output requests

for filesfor files

Processes them in the order receivedProcesses them in the order received

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4040Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Sharing Printing ResourcesSharing Printing Resources

Spooling: program writes a line to a diskSpooling: program writes a line to a disk

file rather than sending directly to a printerfile rather than sending directly to a printer

When file is completed, placed in queueWhen file is completed, placed in queue

File printed when printer becomes availableFile printed when printer becomes available

Allows program to complete executionAllows program to complete execution

much more quicklymuch more quickly

Writing to disk much quicker than writing toWriting to disk much quicker than writing to

printerprinter

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4141Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Utility ProgramsUtility Programs

Perform secondary choresPerform secondary chores

ExamplesExamples

File managerFile manager File compressionFile compression

OthersOthers

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4242Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

File ManagerFile Manager

Stores files in aStores files in a

hierarchical directoryhierarchical directory

structurestructure

Windows usesWindows usesWindows ExplorerWindows Explorer

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4343Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

File CompressionFile Compression

Reduces amount ofReduces amount of

space a file requiresspace a file requires

Makes file take up lessMakes file take up less

space on diskspace on disk Takes less time toTakes less time to

transmit acrosstransmit across

communication linescommunication lines

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4444Copyright 2003 by Prentice HallCopyright 2003 by Prentice Hall

Other Utility ProgramsOther Utility Programs

Backup and RestoreBackup and Restore

Backup: make copies of disks and store in aBackup: make copies of disks and store in asafe placesafe place

Restore: restore files from backupsRestore: restore files from backupsDisk defragmenter: reorganizes disk so allDisk defragmenter: reorganizes disk so allfiles are stored in contiguous locationsfiles are stored in contiguous locations

Device driver: handles commands forDevice driver: handles commands fordevices, such as printers and storagedevices, such as printers and storagedevicesdevices

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