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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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ObjectivesObjectivesDescribe the functions of an operating systemDescribe the functions of an operating systemExplain the basics of a personal computer operating Explain the basics of a personal computer operating systemsystemDescribe the advantages of a graphical operating systemDescribe the advantages of a graphical operating systemDifferentiate among different versions of Microsoft Differentiate among different versions of Microsoft WindowsWindowsExplain the need for network operating systemsExplain the need for network operating systemsDescribe the methods of resource allocation on large Describe the methods of resource allocation on large computerscomputersDescribe the differences among multiprocessing, Describe the differences among multiprocessing, multiprogramming, and time-sharingmultiprogramming, and time-sharingExplain the principles of memory managementExplain the principles of memory managementList several functions that are typically performed by List several functions that are typically performed by utility programsutility programs

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Operating Systems: Hidden SoftwareOperating Systems: Hidden Software

Serves as intermediary between hardware Serves as intermediary between hardware and applications softwareand applications software

Operating SystemOperating System

Systems softwareSystems software

KernelKernel

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Operating SystemOperating System

A set of programs that lies A set of programs that lies between applications software between applications software and the hardwareand the hardware Manages computer’s resources Manages computer’s resources

(CPU, peripheral devices)(CPU, peripheral devices) Establishes a user interfaceEstablishes a user interface

Determines how user interacts with Determines how user interacts with operating systemoperating system

Provides and executes services Provides and executes services for applications softwarefor applications software

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Systems SoftwareSystems Software

All programs related to coordinating All programs related to coordinating computer operationscomputer operations

ExamplesExamples Operating systemsOperating systems Language translatorsLanguage translators

Convert program code to machine-readable formConvert program code to machine-readable form Utility programsUtility programs

Perform secondary choresPerform secondary chores

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KernelKernel

Manages the operating systemManages the operating system Loaded from hard drive into memory when Loaded from hard drive into memory when

computer is bootedcomputer is bootedBootingBooting refers to starting the computer refers to starting the computer

Loads other operating system programs from Loads other operating system programs from disk storage as neededdisk storage as needed

Other programs referred to as Other programs referred to as nonresidentnonresident

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Operating Systems for Personal Operating Systems for Personal ComputersComputers

Platform: combination of computer hardware and Platform: combination of computer hardware and operating system softwareoperating system software WintelWintel (Microsoft Windows running on an Intel-based (Microsoft Windows running on an Intel-based

PC) is one of the most commonPC) is one of the most common

Common PlatformsCommon Platforms MS-DOSMS-DOS WindowsWindows MAC OSMAC OS UnixUnix LinuxLinux

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Graphical User InterfaceGraphical User Interface

User clicks an icon to User clicks an icon to perform tasksperform tasks

Start Menu in lower Start Menu in lower left corner launches left corner launches programsprograms

Use menus to Use menus to activate commandsactivate commands

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Windows XPWindows XP

Brings consumer and Brings consumer and corporate versions of corporate versions of Windows together into a Windows together into a single productsingle product Has Home and Professional Has Home and Professional

EditionsEditions

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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 personalizationMultiple user supportMultiple user support User can log off, leaving programs running, and allow User 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., no Set up limited accounts for children to use; i.e., no

inappropriate games or no Internet accessinappropriate games or no Internet access

Internet support and protectionInternet support and protection

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Operating Systems for NetworksOperating Systems for Networks

Network operating system (NOS) Network operating system (NOS) Handles network functionsHandles network functions

Sharing resources (hard disks and printers)Sharing resources (hard disks and printers)

Data securityData security

TroubleshootingTroubleshooting

Administrative controlAdministrative control Make resources appear as though they were Make resources appear as though they were

running from client computersrunning from client computers

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Operating Systems for Large Operating Systems for Large ComputersComputers

Resource allocation: assigning computer Resource allocation: assigning computer resources to certain programs and processes for resources to certain programs and processes for their usetheir useMain issues related to resource allocationMain issues related to resource allocation Sharing the Central Processing UnitSharing the Central Processing Unit

MultiprocessingMultiprocessingMultiprogrammingMultiprogrammingTime-SharingTime-Sharing

Sharing memorySharing memory Sharing storage resourcesSharing storage resources Sharing printing resourcesSharing printing resources

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Sharing the CPUSharing the CPUMultiprocessingMultiprocessing The use of a powerful computer with multiple CPUsThe use of a powerful computer with multiple CPUs Multiple programs run simultaneously (each runs on Multiple programs run simultaneously (each runs on

its own processor)its own processor)

MultiprogrammingMultiprogramming Two or more programs executed concurrentlyTwo or more programs executed concurrently

Programs take turns using the CPUPrograms take turns using the CPUEvent-drivenEvent-driven

Time-SharingTime-Sharing Programs take turns using the CPUPrograms take turns using the CPU Time-drivenTime-driven Typically used in applications with many usersTypically used in applications with many users

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Sharing MemorySharing MemoryMemory managementMemory management

Divides memory into foreground and backgroundDivides memory into foreground and background

Uses virtual storage (also called virtual memory)Uses virtual storage (also called virtual memory) Programs currently executed are stored on disk Programs 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 by Can be implemented by pagingpaging

Divide memory into small, fixed-size pagesDivide memory into small, fixed-size pages

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

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Sharing Storage ResourcesSharing Storage Resources

Keeps track of location of filesKeeps track of location of files

Responds to commands to manipulate Responds to commands to manipulate filesfiles

Keeps track of input and output requests Keeps track of input and output requests for filesfor files Processes them in the order receivedProcesses them in the order received

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Sharing Printing ResourcesSharing Printing Resources

Spooling: program writes a line to a disk Spooling: 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 execution Allows program to complete execution much more quicklymuch more quickly Writing to disk much quicker than writing to Writing to disk much quicker than writing to

printerprinter

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Utility ProgramsUtility ProgramsPerform secondary chores – some examples:Perform secondary chores – some examples:

File managerFile managerStores files in a hierarchical Stores files in a hierarchical directory structuredirectory structureWindows uses Windows ExplorerWindows uses Windows Explorer

File compressionFile compressionReduces amount of space a file requiresReduces amount of space a file requires

Makes file take up less space on diskMakes file take up less space on disk Takes less time to transmit across Takes less time to transmit across

communication linescommunication lines

OthersOthersBackup and RestoreBackup and Restore

Backup: make copies of Backup: make copies of disks and store in a safe disks and store in a safe placeplace

Restore: restore files Restore: restore files from backupsfrom backups

Disk defragmenter: Disk defragmenter: reorganizes disk so all files reorganizes disk so all files are stored in contiguous are stored in contiguous locationslocations

Device driver: Device driver: handles commands for handles commands for devices, such as printers devices, such as printers and storage devicesand storage devices

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Types of System Software? Functions?

Utility Programs? Operating Systems?

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Graphical user interface (GUI)Graphical user interface (GUI)KernelKernelMemory managementMemory managementMultiprocessingMultiprocessingMultiprogrammingMultiprogrammingOperating systemOperating systemPartitionsPartitionsPlatformPlatform

Terms to Know: Terms to Know: Chapter 3Chapter 3

Resource AllocationResource AllocationResponse timeResponse timeSpoolingSpoolingTime shareTime shareUtility programsUtility programsVirtual Memory/StorageVirtual Memory/Storage

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Can You Explain If Asked?Can You Explain If Asked?Describe the functions of an operating systemDescribe the functions of an operating systemExplain the basics of a personal computer operating Explain the basics of a personal computer operating systemsystemDescribe the advantages of a graphical operating systemDescribe the advantages of a graphical operating systemDifferentiate among different versions of Microsoft Differentiate among different versions of Microsoft WindowsWindowsExplain the need for network operating systemsExplain the need for network operating systemsDescribe the methods of resource allocation on large Describe the methods of resource allocation on large computerscomputersDescribe the differences among multiprocessing, Describe the differences among multiprocessing, multiprogramming, and time-sharingmultiprogramming, and time-sharingExplain the principles of memory managementExplain the principles of memory managementList several functions that are typically performed by List several functions that are typically performed by utility programsutility programs

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SourcesSources

Capron; Computers: Tools for An Capron; Computers: Tools for An Information Age, 8Information Age, 8thth Ed. 2003 Ed. 2003

Pfaffenberger; Computers in Your Future Pfaffenberger; Computers in Your Future 20032003

Microsoft ClipartMicrosoft Clipart

WebopediaWebopedia