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Technology In ActionTechnology In Action

Chapter 4Chapter 4

Using System Software: Using System Software:

The Operating System, Utility Programs The Operating System, Utility Programs (and File Management) (and File Management)

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Application Software Application Software and System Softwareand System Software

• Application software helps people Application software helps people carry out tasks using a computercarry out tasks using a computer– word processing, spreadsheets, gamesword processing, spreadsheets, games– music, databases, educational, referencemusic, databases, educational, reference

• System software helps the computer System software helps the computer carry out basic operating functionscarry out basic operating functions– operating systemsoperating systems– device drivers, utilities, programming device drivers, utilities, programming

languageslanguages

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System SoftwareSystem Software

Operating SystemOperating System• Control computer Control computer

functions:functions:– Hardware Hardware – Memory Memory – Application programsApplication programs– System maintenanceSystem maintenance

• Provide user Provide user interfaceinterface

System UtilitiesSystem Utilities• Programs that perform Programs that perform

computer computer housekeeping tasks:housekeeping tasks:– Manage system Manage system

resourcesresources– Improve efficiencyImprove efficiency– Virus preventionVirus prevention

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What the Operating System What the Operating System DoesDoes

• Provides a user Provides a user interfaceinterface

• Manages the CPUManages the CPU• Manages memoryManages memory• Manages hardwareManages hardware• Coordinates Coordinates

application application software with the software with the CPUCPU

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The User InterfaceThe User Interface

• Enables you to Enables you to interact with the interact with the computercomputer

• Types of Types of interfaces:interfaces:– Command-line Command-line

interface (CLIs)interface (CLIs)– Graphical user Graphical user

interfaceinterface

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Graphical User Interfaces Graphical User Interfaces (GUIs)(GUIs)

• Mac OS, like Windows, bases their Mac OS, like Windows, bases their user interface on the graphical model user interface on the graphical model pioneered at Xerox PARCpioneered at Xerox PARC

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MAC OSMAC OS• First operating system with point-and-click First operating system with point-and-click

technology (Graphical User Interface) (1984)technology (Graphical User Interface) (1984)• Excellent in:Excellent in:

– Graphics displayGraphics display– Processing capabilitiesProcessing capabilities– System reliabilitySystem reliability– Document recoveryDocument recovery

• Latest version OS-X Latest version OS-X in 2000 based on in 2000 based on

UnixUnix

MAC OS X

Microsoft WindowsMicrosoft Windows• one of first GUIs offered for an Intel

PC• many different versions• latest is Windows 7

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UNIXUNIX

• Multiuser, multitasking operating Multiuser, multitasking operating systemsystem

• Used with all sizes of computersUsed with all sizes of computers

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UNIXUNIX

• UNIXUNIX is an operating system developed at Bell is an operating system developed at Bell Labs in the 60’s by Dennis Ritchie and Ken Labs in the 60’s by Dennis Ritchie and Ken ThompsonThompson

• Not built around any one particular family of Not built around any one particular family of microprocessors—highly microprocessors—highly portableportable. Example: . Example: basis of Apple's basis of Apple's Mac OS X TigerMac OS X Tiger

• Often used in servers or work-horse machines Often used in servers or work-horse machines which must be very which must be very stablestable and secure and secure ( uptime )( uptime )

• Newer versions of UNIX use a Newer versions of UNIX use a GUI GUI and are and are friendlier to use than the original OS. friendlier to use than the original OS.

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LinuxLinux

• Open-source Open-source operating system operating system

• Based on UNIXBased on UNIX• Stable, portable Stable, portable

systemsystem• FreeFree• May be downloaded May be downloaded

through the Internetthrough the Internet

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LinuxLinux • LinuxLinux is a version of Unix originally is a version of Unix originally

created in 1991 by Linus Torvalds.created in 1991 by Linus Torvalds.• Linux is Linux is oopen-sourcepen-source software; has been software; has been

collaboratively written by volunteer collaboratively written by volunteer programmers all over the world.programmers all over the world.

• Recent increased support from big name Recent increased support from big name companies (Sun, IBM, HP, and Novell, for companies (Sun, IBM, HP, and Novell, for instance) has increased the use and instance) has increased the use and support of Linux.support of Linux.

• Used on many web serversUsed on many web servers

Linus TorvaldsLinus Torvalds

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CPU ManagementCPU Management

• A computer can take advantage of A computer can take advantage of performance-enhancing technologiesperformance-enhancing technologies– Multitasking (time sharing)Multitasking (time sharing)

• Ctrl+Alt+Del, Alt+Tab - Task managementCtrl+Alt+Del, Alt+Tab - Task management• Foreground, backgroundForeground, background

– MultithreadingMultithreading

divide a task divide a task

into threadsinto threads– MultiprocessingMultiprocessing

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Operating System Operating System CategoriesCategories

• Three categories:Three categories:– Single-User, Single-TaskingSingle-User, Single-Tasking– Single-User, MultitaskingSingle-User, Multitasking– Multiuser (must be multitasking)Multiuser (must be multitasking)

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Single-User Operating Single-User Operating SystemsSystems

Single-task systemsSingle-task systems• Perform one task at a timePerform one task at a time• PDAs:PDAs:

– Pocket PCPocket PC– Palm OSPalm OS– Windows MobileWindows Mobile

• MS-DOSMS-DOS

Multitask systemsMultitask systems• Perform simultaneous Perform simultaneous

taskstasks• WindowsWindows• MAC OSMAC OS• Unix / LinuxUnix / Linux

MultitaskingMultitasking• An illusion!• CPU has to juggle many jobs• Each application gets a time slice• Others are paused while one runs• Fast enough to look simultaneous

Multitasking- Single core, Multitasking- Single core, Dual coreDual core

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Multiuser Operating Multiuser Operating Systems Systems

• Known as network operating systemsKnown as network operating systems• Allow access to the computer system Allow access to the computer system

by more than one userby more than one user• Manage user requestsManage user requests• Systems include:Systems include:

– UNIXUNIX– Novell NetwareNovell Netware– Windows Server 2003Windows Server 2003

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Memory ManagementMemory Management

• The operating system allocates The operating system allocates space in RAM for instructions and space in RAM for instructions and datadata

RAM

Operating

System

Chapter 3: Computer Software22

Increased EfficiencyIncreased Efficiency

• Memory ManagementMemory Management– Virtual Memory - good!Virtual Memory - good!– Memory leaks - bad!Memory leaks - bad!

• Buffering - Buffering - A A bufferbuffer is an area in RAM or is an area in RAM or on the hard drive used to hold input and on the hard drive used to hold input and output on their way in or out of system. output on their way in or out of system. – Print QueuesPrint Queues– Large File DownloadsLarge File Downloads– I/O BuffersI/O Buffers

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Virtual MemoryVirtual Memory

• Instructions and data are stored on Instructions and data are stored on the hard drive when RAM is fullthe hard drive when RAM is full– Swap fileSwap file– Paging Paging – Thrashing Thrashing

Operating

System

FULL

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Hardware ManagementHardware Management

• Device drivers:Device drivers:– Programs that enable the Programs that enable the

operating system to operating system to communicate with communicate with peripheral devicesperipheral devices

– Provided by the Provided by the manufacturer of the manufacturer of the device device

• Plug and Play:Plug and Play:– Hardware and software Hardware and software

standardstandard– Facilitates the Facilitates the

installation of new installation of new hardwarehardware

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Utility ProgramsUtility Programs

• Small application programs that Small application programs that perform special functions:perform special functions:– Manage system resourcesManage system resources– Create pleasant environmentCreate pleasant environment– Improve efficiencyImprove efficiency

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UtilitiesUtilities

• Backup utilitiesBackup utilities• File managers - Windows ExplorerFile managers - Windows Explorer• Screen saversScreen savers• File compression - WinZipFile compression - WinZip• Anti-virus protectionAnti-virus protection• Spam filtersSpam filters• Encryption - PGPEncryption - PGP• Defragmentation of storageDefragmentation of storage

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Display UtilitiesDisplay Utilities

• Change the appearance of:Change the appearance of:– DesktopDesktop– Windows colorsWindows colors– Font sizesFont sizes– Screen saversScreen savers

• saving from what?saving from what?

– Screen resolutionScreen resolution

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Add or Remove ProgramsAdd or Remove Programs

• Installation wizardInstallation wizard• Uninstall wizard:Uninstall wizard:

– Do not just delete programs from Program Files Do not just delete programs from Program Files folder!folder!

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File Compression ProgramsFile Compression Programs

• Reduce the size of a file:Reduce the size of a file:– Removes redundanciesRemoves redundancies– Some types of files do not Some types of files do not

compress well - JPG, MP3, compress well - JPG, MP3, GIF, PNGGIF, PNG

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System Maintenance System Maintenance UtilitiesUtilities

• Disk cleanupDisk cleanup– Cleans Cleans

unnecessary filesunnecessary files• Recycle binRecycle bin• Temporary Internet Temporary Internet

filesfiles• Cached Web pagesCached Web pages

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System Maintenance System Maintenance UtilitiesUtilities

• Disk defragmenterDisk defragmenter• ScanDisk:ScanDisk:

– Error-checkerError-checker

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System Maintenance System Maintenance UtilitiesUtilities

• Task managerTask manager– controls processes controls processes

and applicationsand applications– can halt one that is can halt one that is

out of control "Not out of control "Not Responding"Responding"

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Restore UtilitiesRestore Utilities

• UndeleteUndelete– How? Why?How? Why?

• System System Restore:Restore:– Restores the Restores the

system settings system settings back to a back to a specific datespecific date

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Accessibility UtilitiesAccessibility Utilities

• Utility manager:Utility manager:– Magnify screen Magnify screen

imageimage– Screen contents Screen contents

narrationnarration– On-screen keyboardOn-screen keyboard