Operating System BasicsOperating SystemOperating System ObjectivesLayers of Computer SystemsServices Provided by the Operating SystemFunctions of Operating SystemsTypes of Operating SystemsEnhancing an OS

Operating SystemA program that controls the execution of application programsAn interface between applications and hardware

Operating System ObjectivesConvenienceMakes the computer more convenient to useEfficiencyAllows computer system resources to be used in an efficient mannerAbility to evolvePermit effective development, testing, and introduction of new system functions without interfering with service

Layers of Computer System

Services Provided by the Operating SystemProgram developmentEditors and debuggersProgram executionAccess to I/O devicesControlled access to filesSystem access

Services Provided by the Operating SystemError detection and responseinternal and external hardware errorsmemory errordevice failuresoftware errorsarithmetic overflowaccess forbidden memory locationsoperating system cannot grant request of application

Services Provided by the Operating SystemAccountingcollect statisticsmonitor performanceused to anticipate future enhancementsused for billing users

Copyright 2006 by The McGraw-Hill Companies, Inc. All rights reserved.McGraw-Hill Technology Education

Operating System BasicsRef Book: Chapter # 7:Introduction to Computers , Peter NortonMcGraw-Hill.

www.mhhe.com/peternorton

Functions of Operating SystemsProvide a user interfaceRun programsManage hardware devicesOrganized file storage

Providing a User InterfaceUser interfaceHow a user interacts with a computerRequire different skill sets

Providing a User InterfaceGraphical user interface (GUI)Most common interfaceWindows, OS X, Gnome, KDEUses a mouse to control objectsUses a desktop metaphorShortcuts open programs or documentsOpen documents have additional objectsTask switchingDialog boxes allow directed input

Graphical User Interface

Providing a User InterfaceCommand line interfacesOlder interfaceDOS, Linux, UNIXUser types commands at a promptUser must remember all commandsIncluded in all GUIs

Command Line Interface

Running ProgramsMany different applications supportedSystem callProvides consistent access to OS featuresShare information between programsCopy and pasteObject Linking and Embedding

Managing HardwarePrograms need to access hardwareInterruptsCPU is stoppedHardware device is accessedDevice drivers control the hardware

Organizing Files and FoldersOrganized storageLong file namesFolders can be created and nestedAll storage devices work consistently

Types of Operating SystemsReal-time operating systemVery fast small OSBuilt into a deviceRespond quickly to user inputMP3 players, Medical devices

Types of Operating SystemsSingle user/Single tasking OSOne user works on the systemPerforms one task at a timeMS-DOS and Palm OSTake up little space on diskRun on inexpensive computers

Single TaskingOperating System cannot be able to take control back from the running process/task/applicationIn case if a process call an I/O Instruction then Processor must wait for I/O instruction to complete before preceding

Types of Operating SystemsSingle user/Multitasking OSUser performs many tasks at onceMost common form of OSWindows XP and OS XRequire expensive computersTend to be complex

MultitaskingOperating System can take control back from the running process and can give it to other. When one job needs to wait for I/O, the processor can switch to the other job

Types of Operating SystemsMulti user/Multitasking OSMany users connect to one computerEach user has a unique sessionUNIX, Linux, and VMSMaintenance can be easyRequires a powerful computer

Multi user/Multi tasking OS

Enhancing an OSUtilitiesProvide services not included with OSGoes beyond the four functionsFirewall, anti-virus and compressionPrices vary

Enhancing an OSBackup softwareArchives files onto removable mediaEnsures data integrityMost OS include a backup packageMany third party packages exist

Backup Software

Enhancing an OSAnti-virus softwareCrucial utilityFinds, blocks and removes virusesMust be updated regularlyMcAfee and Norton Anti-Virus

Enhancing an OSFirewallCrucial utilityProtects your computer from intrudersMakes computer invisible to hackersZone Labs is a home firewallCisco sells hardware firewalls

Enhancing an OSIntrusion detectionOften part of a firewall packageAnnounces attempts to breach securitySnort is a Linux based package

Enhancing an OSScreen saversCrucial utility for command line systemsPrevents burn inMerely fun for GUI systemsScreen saver decorates idle screens

Copyright 2006 by The McGraw-Hill Companies, Inc. All rights reserved.McGraw-Hill Technology Education

Reference Book:Introduction to Computers , Peter NortonMcGraw-Hill.

www.mhhe.com/peternorton

Teaching TipFile and folder storage is covered in chapter 6. Insider informationThe first commercial GUI was the Xerox Star.

Teaching TipThere are several types of dialog boxes. Any errors are displayed in a dialog box. This box is system modal - it requires a response before returning to the OS. Save and print boxes are application modal - The box must be dealt with before returning to the application. However, other OS tasks can be performed.Teaching tipDemonstrate the command line interface in Windows by running cmd. In the command line interface use ping and ipconfig as commands that cannot be run in the GUI. Teaching tipMost students have never encountered a link. I use MS Excel and MS Word to link. Create and save a simple spreadsheet in Excel. Copy the spreadsheet to the clipboard. Open MS Word and paste-link the spreadsheet. Save the MS Word document. Then change and save the spreadsheet in Excel. The word document is automatically updated. Discussion pointThe mouse uses an interrupt. Many users will move the mouse while waiting for the CPU to finish a task. What does moving the mouse do to the current process?

Teaching tipDiscuss what can happen when the wrong driver is installed on a computer. Teaching tipIt is true that multi-tasking operating systems are complex. However both XP and OS X make the multitasking process painless for the user. Teaching tipMulti-user Multitasking OS's are found on supercomputers, mainframes and minicomputers. Through Linux, a PC can also support user sessions and terminal connections. Discussion pointWith Windows XP and SP2, Microsoft has included a firewall and pop-up blocker both typically considered utility software. In the near future, the core services provided by an OS may include security features. Teaching tipWindows XP includes a firewall. Service pack 2 will turn this firewall on by default. To test your computers security visit www.grc.com and run the various Shields Up! tests