计算机专业英语：第3章

ComputerProfessionalEnglishChapter3目录FundamentalsofComputerHardwareOperatingSystemPrinciplesandApplicationsFundamentalsofComputerNetworkTechnology目录PrinciplesandApplicationsofDatabaseSystemsSoftwaredevelopmentmethodsandtools01FundamentalsofComputerHardwareDefinitionTheCentralProcessingUnit(CPU)isthebrainofthecomputer,responsibleforexecutinginstructionsandperformingcalculationsComponentsItinsistsofthearithmeticlogicunit(ALU)forperformingarithmeticandlogicaloperations,thecontrolunitformanagingtheflowofinstructions,andregistersfortemporarydatastoragePerformanceMetricsTheperformanceofaCPUismeasuredintermsofclockspeed(inGHzorMHz),numberofcores,andcachesizeCentralProcessingUnitDefinition01ComputermemoryreferstothephysicaldevicesusedtostoredataandinstructionstemporarilyorpermanentlyTypes02Therearetwomaintypesofmemory-primarymemory(RAMandROM)andsecondarymemory(harddrives,solidstatedrives,opticaldrives)Hierarchy03Memoryisorganizedinahierarchybasedonspeed,capacity,andcost,withthefastestandmostexpensivememoryclosedtotheCPUMemorystorageInput/output(I/O)devicesallowuserstointeractwiththecomputeranditsdataDefinitionCommoninputdevicesincludekeyboards,mice,scanners,andmicrophonesCommonoutputdevicesincludemonitors,printers,andspeakersTypesI/OdevicesconnecttothecomputerthroughvariousinterfacessuchasUSB,HDMI,andBluetoothInterfacesInput/outputdevicesDefinitionAbusisacommunicationsystemthattransfersdatabetweencomponentsinsideacomputerorbetweencomputersTypesThereareseveraltypesofbuses,includingthesystembus(connectsCPUtomemory),expansionbus(connectsCPUtootherdevices),andperipheralbus(connectsperipheralstothecomputer)StandardsCommonbusstandardsincludePCIExpress,USB,Thunderbolt,andSATAEachstandardhasitsownspeed,cabletype,andconnectortypeBusandInterface02OperatingSystemPrinciplesandApplications010203DefinitionandRoleofOperatingSystemAnoperatingsystemisasoftwarethatmanagescomputerhardwareandsoftwareresources,providingcommonservicesforcomputerprogramsTypesofOperatingSystemsTherearevarioustypesofoperatingsystems,includingbatchoperatingsystems,timesharingoperatingsystems,real-timeoperatingsystems,networkoperatingsystems,anddistributedoperatingsystemsOperatingSystemStructuresOperatingsystemscanbestructuredindifferentways,suchasmonolithic,microkernel,andhybridstructuresOperatingSystemOverviewAprocessisaprograminexecutionItincludestheprogramcode,data,andtheexecutioncontextProcessConceptsProcessescanbeindifferentstates,suchasnew,ready,running,waiting,andterminatedProcessStatesOperatingsystemsusevariableschedulingalgorithmstodeterminewhichprocessshouldbeallocatedtotheCPUforexecutionProcessSchedulingProcessescancommunicatewitheachotherthroughvariousmechanismsprovidedbytheoperatingsystem,suchaspipes,messagequeues,andsharedmemoryInterprocessCommunicationProcessmanagementMemoryManagementOperatingsystemsmanagingmemorybyallocatingittoprocesses,protectingmemoryfromunauthorizedaccess,andprovidingmechanismsforeffectivememoryutilizationVirtualMemoryVirtualmemoryisatechnologythatallowsprocessestoaccessmorememorythatisphysicallyavailablebyusingdiskspaceasanextensionofmainmemoryFileSystemsFilesystemsareusedtoorganizeandstoredataondiskdrivesTheyprovideahierarchicalstructurefororganizingfilesanddirectories,aswellasmechanismsforaccessingandmanipulatingfilesStorageManagement要点三FileConceptsFilesarenamedcollectionsofrelateddatathatarestoredondiskdrivesTheycanbeorganizedindifferentways,suchassequential,indexedsequential,anddirectaccess要点一要点二FileOperationsOperatingsystemsprovideasetoffileoperationsforcreating,opening,reading,writing,andclosingfilesFileProtectionandSecurityOperatingsystemsprovidemechanismsforprotectingfilesfromunauthorizedaccessandensuringdatasecurityThisincludesfilepermissions,accesscontrollists,andencryptiontechniques要点三FileManagement03FundamentalsofComputerNetworkTechnologyOverviewofComputerNetworksDefinitionandTypesofComputerNetworks:AcomputernetworkisagroupofinterconnectedcomputersthatshareresourcesandcommunicatewitheachotherNetworkscanbeclassifiedintodifferenttypesbasedontheirsize,scope,andpurpose,suchasLocalAreaNetworks(LANs),WideAreaNetworks(WANs),andtheInternetNetworkTopologies:Networktopologiesdescribethelayoutorstructureofanetwork,includingstar,ring,bus,mesh,andhybridtopologiesEachtopologyhasitsownadvantagesanddisadvantagesintermsofperformance,reliability,andcostNetworkprotocolsandstandards:NetworkprotocolsaresetsofrulesthatgoverncommunicationbetweendevicesonanetworkCommonprotocolsincludeTCP/IP,HTTP,andSMTPStandardsorganizationssuchastheIEEEandISOdevelopandmaintainstandardsfornetworkprotocolsandtechnologiesEthernetisthemostwidelyusedLANtechnology,providinghighspeeddatatransmissionovertwistedpairorfiberopticcablesItoperatesatdifferentspeeds,including10Mbps,100Mbps,1Gbps,and10GbpsWirelessLANs(WLANs)useradiowavestotransmitdatabetweendevices,refiningtheneedforwiredconnectionsCommonWLANstandardsinclude802.11a,802.11b,802.11g,802.11n,and802.11acSwitchedEthernetusesnetworkswitchestoconnectdevicesonaLAN,providingdegradedbandwidthandimprovedperformancecomparedtosharedEthernetEthernetWirelessLANsSwitchedEthernetLANtechnologyCircuitSwitchednetworksestablishadedicatedconnectionbetweentwopointsforthedurationofacommunicationsessionTheyaretypicallyusedforvoicecommunicationsandprovideguaranteedbandwidthandlowlatencyPacketSwitchednetworksbreakdataintosmallpacketsthataretransmittedindependentlyoverthenetworkandreassembledatthedestinationTheyareeffectivefordatacommunicationsandcanhandleburstsoftrafficwellBroadbandtechnologiessuchasDSL,cablemodes,andfiberopticsprovidehighspeeddatatransmissionoverlongdistancesTheyarecommonlyusedtoconnectLANstotheInternetorotherWANsCircuitSwitchedNetworksPacketSwitchedNetworksBroadbandTechnologiesWANTechnologiesInternetapplicationsWebBrowsing:WebbrowsinginvolvesusingawebbrowsertoaccessandinteractwithwebpagesandwebapplicationsovertheInternetCommonwebbrowsersincludeGoogleChrome,MozillaFirefox,andMicrosoftEdgeEmail:EmailallowsuserstosendandreceivemessagesovertheInternetItisanasynchronouscommunicationtoolthatcanbeusedforpersonalorbusinesspurposesInstantmessaging:Instantmessaging(IM)allowsuserstocommunicateinrealtimeovertheInternetusingtext,audio,orvideoCommonIMplatformsincludeWhatsApp,FacebookMessenger,andSkypeVoiceoverIP(VoIP):VoIPallowsuserstomakevoicecallsovertheInternetusingabroadbandconnectioninstallofatraditionalphonelineItistoocheapandmoreflexiblethantraditionalphoneservice04PrinciplesandApplicationsofDatabaseSystemsDefinitionandEvolutionofDatabaseSystemsAbriefhistoryanddevelopmentofdatabasesystems,fromfilebasedsystemstomoderndatabasemanagementsystems(DBMS)TypesofDatabaseSystemsAnoverviewofdifferenttypesofdatabasesystems,includingrelational,objectoriented,andNoSQLdatabasesBenefitsandApplicationsofDatabaseSystemsDiscussionontheadvantagesofusingdatabasesystems,suchasdataintegrity,security,andefficiency,aswellasexamplesoftheirapplicationsinvariousindustriesOverviewofDatabaseSystemsIntroductiontotheRelationalModelExplanationofthefundamentalconceptsoftherelationalmodel,includingtables,rows,columns,andkeysRelationalAlgebraandCalculusIntroductiontothetheoreticalframeworkformanagingrelationaldata,includingthebasicoperationsofselection,projection,union,andsetdifferenceNormalizationandDenormalizationDiscussionontheimportanceofdatabasenormalizationtoreducedataredundancyandimprovedataintegrity,aswellastheconceptofnormalizationforperformanceoptimizationRelativedatabasemodelBasicSQLQueriesExplanationandexamplesofbasicSQLqueriesforretrieval,insertion,updating,anddeletingdatainadatabaseAdvancedSQLFeaturesIntroductiontoadvancedSQLfeaturessuchassubqueries,joins,aggregatefunctions,andtransactioncontrolIntroductiontoSQLOverviewofthehistory,purpose,andstructureoftheSQLlanguageFundamentalsofSQLLanguageDatabaseDesignProcessOverviewofthestepsinvolvedinthedatabasedesignprocess,includingrequirementsanalysis,conceptualdesign,logicaldesign,andphysicaldesignDataModelingTechniquesDiscussionondifferentdatamodelingtechniquessuchasentityrelationshipdiagram