工業(yè)和信息化人才培養(yǎng)規(guī)劃教材

實用IT英語

Practical

ITEnglish孫潔、李一、湛邵斌主編

目錄TheComputerAge

OperatingSystem

ApplicationSoftware

134ComputerProgramming

5ComputerHardware

2Database

6ComputerNetworks

7WWWandtheInternet

PrivacyandSecurity

Multimedia81011ElectronicCommerce

12CommunicationOnline

9NewTechnologies13YourfutureandIT14Unit1TheComputerAgeWeAreLivingincomputertechnologyandpeople’slivesthefivegenerationsofcomputersandthesignificantadvancementsintechnologyofeachgenerationdifferenttypesofcomputersthefutureofcomputerstipsonhowtowritearesumeforanITjobProfessionalTerminology:vacuumtube;IBM(InternationalBusinessMachinesCorporation);transistor;integratedcircuit(IC);siliconchip;personalcomputer(PC);centralprocessingunit(CPU);desktopcomputer;laptopcomputer;PersonalDigicalAssistant(PDA);mainframe;minicomputer;supercomputer;artificialintelligence(AI)Outline：TheImpactofComputersonPeople’sLives

Hi,Bill!Haveyounoticedthatnowadayscomputersaremuchmoreinvolvedinpeoples’lives?Idoagreewithyou.Computersarepeople’sindispensablecompanionhelpingusdothings.

TheImpactofComputersonPeople’sLivesYes,IalwaysusemycomputertoconnecttotheInternet

tosurftheweb.It’sevenadailyroutineforme.Thesamethingforme,Ican’timaginemylifewithoutacomputer.TheImpactofComputersonPeople’sLives

Ofcoursenot!Ireadnewsstoriesandmoviereviews,gettheweatherforecastnearlyeveryevening.Andwhat’smore,withacomputeryoucanalsosende?mailtomanypeoplesimultaneously,andyoucansave,printandforwarde?mailtoothersandyouevendon'tneedastamp!

TheImpactofComputersonPeople’sLivesThatistrue!Listeningtomusicandwatchingmoviesoncomputerisreallyagoodentertainmentforme!

DoyouknowthemostwonderfulthingIwouldliketodowithacomputer?Thatistoplaycomputergames.ManygamesallowyoutocompetewithotherplayersaroundtheworldthroughtheInternet.TheImpactofComputersonPeople’sLives

Thatsoundsfantastic!Well,justdon’tspendtoomuchtimeonit!Icertainly

willcertainlynot!TextA:TheEvolutionofComputerAge

TheComputerAgedidnotreallybeginuntilthefirstcomputerwasmadeavailabletothepublicin1951.Themodernageofcomputersspansalmost50years,whichistypicallybrokendownintofivegenerations.Eachgenerationismarkedbyasignificantadvancementintechnology:

TextA:TheEvolutionofComputerAge

FirstGeneration(TheVacuumTubeAge1951-1957):

Duringthisgeneration,computerswerebuiltwithvacuumtubes—electronictubesthatweremadeofglassandwereaboutthesizeoflightbulbs.Thesecomputerswereexpensiveandbulky.Theyusedmachinelanguageforcomputingandcouldsolvejustoneproblematatime.Intheyear1951,thefirstcommerciallyavailableelectronicdigitalcomputerwasintroducedtothepublic,whichmarkedthefirstgenerationcomputerscameintobeing.IBM(InternationalBusinessMachinesCorporation),todayabignameinthelistofcomputertechnologyindustries,announcedtheIBM702ElectronicDataProcessingMachinein1953.Itwasdevelopedforbusinessuseandcouldaddressscientificandengineeringapplications.TextA:TheEvolutionofComputerAge

SecondGeneration(TheTransistorAge1958-1963)

Thisgenerationbeganwiththefirstcomputersbuiltwithtransistors—smalldevicesthattransferredelectronicsignalsacrossaresistor.Becausetransistorsweremuchsmaller,uselesspower,andcreatedlessheatthanvacuumtubes,thenewcomputerswerefaster,smaller,andmorereliablethanthefirst-generationmachineswere.Inthe1960s,transistorbasedcomputersreplacedvacuumtubes.Transistorsmadecomputerssmallerandcheaper.Theymadecomputersenergy-efficient.Theuseoftransistorsmarkedthesecondgenerationofcomputers.TextA:TheEvolutionofComputerAge

ThirdGeneration(TheIntegratedCircuitAge1964-1969)

In1964,computermanufacturersbeganreplacingtransistorswithintegratedcircuits.Anintegratedcircuit(IC)isacompleteelectroniccircuitonasmallchipmadeofsilicon.Thesecomputersweremorereliableandcompactthancomputersmadewithtransistors,andtheycostlesstomanufacture.What’smore,theuseofthenewtypesofcomputerincreasedthespeedandefficiencyofcomputers.Intheyear1965,DigitalEquipmentCorporation(DEC)introducedthefirstminicomputers.TextA:TheEvolutionofComputerAge

FourthGeneration(TheMicroprocessorAge1970-1990)

Thereweremanykeyadvancementsthatweremadeduringthisgeneration,themostsignificantofwhichwastheuseofthemicroprocessor—aspecializedchipdevelopedforcomputermemoryandlogic.Thisrevolutionizedthecomputerindustrybymakingitpossibletouseasinglechiptocreatesmallerpersonalcomputers.Microprocessorscameupduringthe1970s.Intelproducedlarge-scaleintegrationcircuitsin1971.AppleComputer,Inc.,foundedbySteveWozniakandSteveJobs,broughtouttheMacintoshpersonalcomputerin1984.Microsoft,acompanyfoundedbyayoungHarvarddrop-outnamedBillGates,whowrotetheprogramminglanguageBASICforoneoftheearliestmicrocomputers,introducedtheirWindowsgraphicaluserinterfaceintheyear1985.TextA:TheEvolutionofComputerAge

Figure1.MinicomputerFigure2.MicrocomputerTextA:TheEvolutionofComputerAge

FifthGeneration(TheAgeofConnectivity1990andbeyond)

Ourcurrentgenerationhasbeenreferredtoas“ConnectedGeneration”becauseoftheindustry’smassiveefforttoincreasetheconnectivityofcomputers.TherapidlyexpandingInternet,WorldWideWeb,andintranetshavecreatedaninformationhighwaythathasenablebothcomputerprofessionalsandhomecomputeruserstocommunicatewithothersacrosstheglobe.What’smore,presentlythecomputerswouldbecapableofmassiveparallelprocessing,supportvoicerecognitionandunderstandnaturallanguage.Thecurrentadvancementsincomputertechnologyarelikelytotransformcomputingmachinesintointelligentonesthatpossessselforganizingskills.Theevolutionofcomputerswillcontinue,perhapstillthedaytheirprocessingpowersequalhumanintelligence.Exercises161.WhendidtheComputerAgereallybegin?2.Whatarethefivegenerationsofcomputerage?3.Whatisthesignificantadvancementintechnologyofeachgeneration?4.WhoisthefounderofMicrosoftCorporations?Whatdoyouthinkishismaincontributiontothecomputerworld?5.Whyhasthecurrentagebeenreferredtoas“ConnectedGeneration”?Answerthefollowingquestionsaccordingtothetext.17()1.Duringthefirstgeneration,computerswerebuiltwithvacuumtubes—electronictubesthatweremadeofglassandwereaboutthesizeoflightbulbs.()2.IBM702ElectronicDataProcessingMachinewasdevelopedformilitaryuseandcouldaddressscientificandengineeringapplications.()3.Inthe1970s,transistorbasedcomputersreplacedvacuumtubes.()4.Anintegratedcircuit(IC)isacompleteelectroniccircuitonasmallchipmadeofsilicon.()5.Thecurrentgenerationhasbeenreferredtoas“ConnectedGeneration”becauseoftheindustry’smassiveefforttoincreasetheconnectivityofcomputers.Decidewhetherthefollowingstatementsaretrueorfalse.

TTTFFExercisesTextB:DifferenttypesofComputers18Acomputerisoneofthemostbrilliantinventionsofmankind.Thankstothecomputertechnology,wewereabletoachieveanefficientstorageandprocessingofdata;wecouldrestourbrainsbyemployingcomputermemorycapacitiesforstorageofinformation.Owingtocomputers,wehavebeenabletospeedupdailywork,carryoutcriticaltransactionsandachieveaccuracyandprecisioninwork.Computersoftheearlieryearswereofthesizeofalargeroomandwererequiredtoconsumehugeamountsofelectricpower.However,withtheadvancingtechnology,computershaveshrunktothesizeofasmallwatch.Dependingontheprocessingpowerandsizeofcomputers,theyhavebeenclassifiedundervarioustypes.Followingaresomeimportanttypesofcomputers.TextB:DifferenttypesofComputersMainframeComputer:

LargeorganizationsusemainframesforhighlycriticalapplicationssuchasbulkdataprocessingandERP.Mostofthemainframecomputershavethecapacitiestohostmultipleoperatingsystemsandoperateasanumberofvirtualmachinesandcanthussubstituteforseveralsmallservers.TextB:DifferenttypesofComputersTextB:DifferenttypesofComputersMicrocomputer

Acomputerwithamicroprocessoranditscentralprocessingunitisknownasamicrocomputer.Theydonotoccupyspaceasmuchasmainframes.Whensupplementedwithakeyboardandamouse,microcomputerscanbecalledpersonalcomputers.Amonitor,akeyboardandothersimilarinputoutputdevices,computermemoryintheformofRAMandapowersupplyunitcomepackagedinamicrocomputer.Thesecomputerscanfitondesksortablesandserveasthebestchoicesforsingle-usertasks.Personalcomputerscomeinavarietyofformssuchasdesktops,laptopsandpersonaldigitalassistants.Letuslookateachofthesetypesofcomputers.TextB:DifferenttypesofComputersTextB:DifferenttypesofComputersDesktop:

Adesktopisintendedtobeusedonasinglelocation.Thesparepartsofadesktopcomputerarereadilyavailableatrelativelowercosts.Powerconsumptionisnotascriticalasthatinlaptops.Desktopsarewidelypopularfordailyuseinworkplacesandhouseholds.

TextB:DifferenttypesofComputersTextB:DifferenttypesofComputersLaptop:

Similarinoperationtodesktops,laptopcomputersareminiaturizedandoptimizedformobileuse.Laptopsrunonasinglebatteryoranexternaladapterthatchargesthecomputerbatteries.Theyareenabledwithaninbuiltkeyboard,touchpadactingasamouseandaliquidcrystaldisplay.Itsportabilityandcapacitytooperateonbatterypowerhaveservedasaboonformobileusers.TextB:DifferenttypesofComputersTextB:DifferenttypesofComputersPersonalDigitalAssistant(PDA):

PDAsarehandheldcomputersandpopularlyknownaspalmtops.Theyhavegottouchscreenandamemorycardforstorageofdata.PDAscanalsobeeffectivelyusedasportableaudioplayers,webbrowsersandsmartphones.MostPDAscanaccesstheInternetbymeansofBluetoothorWi-Ficommunication.TextB:DifferenttypesofComputersTextB:DifferenttypesofComputersMinicomputer:

Intermsofsizeandprocessingcapacity,minicomputerslieinbetweenmainframesandmicrocomputers.Minicomputersarealsocalledmid-rangesystemsorworkstations.Thetermbegantobepopularlyusedinthe1960storefertorelativelysmallerthirdgenerationcomputers.Theytookupthespacethatwouldbeneededforarefrigeratorortwoandusedtransistorandcorememorytechnologies.The12-bitPDP-8minicomputeroftheDigitalEquipmentCorporationwasthefirstsuccessfulminicomputer.TextB:DifferenttypesofComputersTextB:DifferenttypesofComputersSupercomputer:

Thehighlycalculation-intensivetaskscanbeeffectivelyperformedbymeansofsupercomputers.Quantumphysics,mechanics,weatherforecasting,moleculartheoryarebeststudiedbymeansofsupercomputers.Theirabilityofparallelprocessingandtheirwell-designedmemoryhierarchygivethesupercomputers,largetransactionprocessingpowers.TextB:DifferenttypesofComputersTextB:DifferenttypesofComputersWearableComputer:

Arecord-settingstepintheevolutionofcomputerswasthecreationofwearablecomputers.Thesecomputerscanbewornonthebodyandareoftenusedinthestudyofbehaviormodelingandhumanhealth.Militaryandhealthprofessionalshaveincorporatedwearablecomputersintotheirdailyroutine,asapartofsuchstudies.Whentheusers'handsandsensoryorgansareengagedinotheractivities,wearablecomputersareofgreathelpintrackinghumanactions.Wearablecomputersareconsistentlyinoperationastheydonothavetobeturnedonandoffandareconstantlyinteractingwiththeuser.TextB:DifferenttypesofComputersTheseweresomeofthedifferenttypesofcomputersavailabletoday.Lookingattherateoftheadvancementintechnology,wecandefinitelylookforwardtomanymoretypesofcomputersinthenearfuture.TextB:DifferenttypesofComputers281._______isahandheldcomputerandpopularlyknownasapalmtop.2._________________canbewornonthebodyandareoftenusedinthestudyofbehaviormodelingandhumanhealth.3.Intermsofsizeandprocessingcapacity,______________lieinbetweenmainframesandmicrocomputers.4._______runonasinglebatteryoranexternaladapterthatchargesthecomputerbatteries.5.A_______isintendedtobeusedonasinglelocation.

Fillintheblanksaccordingtothetext.

Wearablecomputers

desktopminicomputers

LaptopsPDAExercises29()1.Thesparepartsofadesktopcomputerarereadilyavailableatrelativehighercosts.()2.Mostofthesupercomputershavethecapacitiestohostmultipleoperatingsystemsandoperateasanumberofvirtualmachinesandcanthussubstituteforseveralsmallservers.()3.PDAscanalsobeeffectivelyusedasportableaudioplayers,webbrowsersandsmartphones.MostofthemcanaccesstheInternetbymeansofBluetoothorWi-Ficommunication.()4.Quantumphysics,mechanics,weatherforecasting,moleculartheoryarebeststudiedbymeansofminicomputers.()5.Wearablecomputersareconsistentlyinoperationastheydonothavetobeturnedonandoffandareconstantlyinteractingwiththeuser.TTTFFExercisesDecidewhetherthefollowingstatementsaretrueorfalse.

TextC:TheFutureofComputers

Asanyonewhohaslookedattheworldofcomputerslatelycanattest,thesizeofcomputershasbeenreducedsharply,evenasthepowerofthesemachineshasincreasedatanexponentialrate.Infact,thecostofcomputershascomedownsomuchthatmanyhouseholdsnowownnotonlyone,buttwo,threeorevenmore,PCs.Astheworldofcomputersandcomputertechnologycontinuestoevolveandchange,manypeople,fromsciencefictionwritersandfuturiststocomputerworkersandordinaryusers,allhavewonderedwhatthefutureholdsforthecomputerandrelatedtechnologies.Manythingshavebeenpictured,fromrobotsintheformofhouseholdservantstocomputerssosmalltheycanfitinapocket.Indeed,someofthesepredictedinventionshavealreadycometopass,withtheintroductionofPDA'sandroboticvacuumcleaners.TextC:TheFutureofComputersTextC:TheFutureofComputers

Beyondtheseinnovations,however,therearelikelytobemany,manymore.Oneofthemostimportantareasofresearchintheworldofcomputersisthatofartificialintelligence.Whenmanypeoplethinkofartificialintelligence,theymaypicturefullyawaremachines,completewithemotions,andtheproblemsthatcanarisefromthem.Eventhoughthisremainsthegoalofmanyartificialintelligenceresearchers,infactartificialintelligencetechnologyisalreadyinplaceandalreadyservingtheneedsofhumanseverywhere.TextC:TheFutureofComputersTextC:TheFutureofComputers

Oneofthemostpowerfulusesofartificialintelligencethusfarisintheworldofspeechrecognition.Thispowerfultechnologyisalreadyinplaceincallcenters,banks,brokeragecenters,insurancecompaniesandotherbusinessesthroughouttheworld.Whilespeechrecognitionisstillimperfect,ithasimprovedgreatlyinrecentyears,andinthefuturemanyroutine,andevennon-routine,phonecallsandtelephoneinquiriesmaybehandledcompletelywithouthumanintervention.TextC:TheFutureofComputersTextC:TheFutureofComputers

Robottechnologyhasalsocomealongway,butitstillhasalongwaytogo.Robotsinthefutureareunlikelytotakehumanform,exceptinafewspecializedapplications.Instead,robotsarelikelytodoagreatdealofworkthatissimplytoodangerousforhumanstoaccomplish.Fromspaceflightapplicationstosearchandrescue,robotsarelikelytocontinuedownthelearningcurvetheyhavealreadyentered,furtherenhancinghumanlivesandprovidingvaluableservicesforafractionofthecostoftoday'srobothelpers.TextC:TheFutureofComputersTextC:TheFutureofComputers

Quantumcomputersarealsolikelytotransformthecomputingexperience,forbothbusinessandhomeusers.Thesepowerfulmachinesarealreadyonthedrawingboard,andtheyarelikelytobeintroducedinthenearfuture.Thequantumcomputerisexpectedtobeagiantleapforwardincomputingtechnology,withexcitingimplicationsforeverythingfromscientificresearchtostockmarketpredictions.TextC:TheFutureofComputersTextC:TheFutureofComputers

Nanotechnologyisanotherimportantpartofthefutureofcomputers,expectedtohaveaprofoundimpactonpeoplearoundtheglobe.Nanotechnologyistheprocesswherebymatterismanipulatedattheatomiclevel,providingtheabilityto“build”objectsfromtheirmostbasicparts.Likeroboticsandartificialintelligence,nanotechnologyisalreadyinuseinmanyplaces,providingeverythingfromstainresistantclothingtobettersuntanlotion.Theseadvancesinnanotechnologyarelikelytocontinueinthefuture,makingthisoneofthemostpowerfulaspectsoffuturecomputing.TextC:TheFutureofComputersTextC:TheFutureofComputers

Andifhistoryistobeanyguide,someofthemostpowerfuladvancesintheworldofcomputersandcomputertechnologyarelikelytobecompletelyunforeseen.Afterall,someofthemostpowerfultechnologiesofthepasthavetakenusbysurprise,sostaytunedforatrulyfascinatingfuture.TextC:TheFutureofComputers37()1.Thesizeofcomputershasbeenreducedsharply,evenasthepowerofthesemachineshasincreasedatanexponentialrate.()2.Thespeechrecognitionisnowperfect,phonecallsandtelephoneinquiriescanbehandledcompletelywithouthumanintervention.()3.Quantumcomputersarelikelytotransformthecomputingexperience,forbothbusinessandhomeusers.()4.Nanotechnologyistheprocesswherebymatterismanipulatedatthemolecularlevel,providingtheabilityto“build”objectsfromtheirmostbasicparts.()5.Likeroboticsandartificialintelligence,quantumtechnologyisalreadyinuseinmanyplaces,providingeverythingfromstainresistantclothingtobettersuntanlotion.FFTFTExercisesDecidewhetherthefollowingstatementsaretrueorfalse.

Discussingroupsonthefollowingissues:Whatarethecomputersgoingtobelikeinthefuture?Whatareyourexpectationsforthecomputersinthefuture?ExercisesHowtoStartYourCareerinInformationTechnology

39

Asawriterofcareer-relatedarticlessince2003,ThomasreceivedhisBachelorofSciencefromtheUniversityofCentralMissouri.Hehasover10yearsinprintingandpublishingandiscurrentlyworkingonseveralindependentwritingprojects.

HowtoStartYourCareerinInformationTechnology1.Pursuetherightdegrees.2.Offerfreelanceprogrammingserviceswhileyouattendschool.3.Seekaninternshipbeforeyougraduate.

4.Developrelatedskills.

5.Maintainagradepointaverage(GPA)ofatleast3.0.

6.Getcertified.

7.SignupforanITjob-placementservice.ClassActivities

Therearemanyremarkablegiantsincomputerworld,whohavedonegreatcontributionstothedevelopmentoftheindustry.Inthissection,youwillbegivenwithsomehintstoguesswhothefigureismentioned.42HeattendedpublicelementaryschoolandtheprivateLakesideSchool.There,hediscoveredhisinterestinsoftwareandbeganprogrammingcomputersatage13.In1973,heenteredHarvardUniversityasafreshman,whileinhisjunioryear,heleftHarvardtodevotehisenergiestoMicrosoft,acompanyhehadbegunin1975withhischildhoodfriendPaulAllen.Guidedbyabeliefthatthecomputerwouldbeavaluabletooloneveryofficedesktopandineveryhome,theybegandevelopingsoftwareforpersonalcomputers.HeisthechairmanofMicrosoftCorporation,theworldwideleaderinsoftware.ClassActivities43HewasborninSanFrancisco,California.In1972,hegraduatedfromHomesteadHighSchoolinCupertino,CaliforniaandenrolledinReedCollegeinPortland,Oregon.Onesemesterlater,hehaddroppedout,latertakingupthestudyofphilosophyandforeigncultures.Hehadadeep-seatedinterestintechnology,sohetookupajobatAtariInc,thenaleadingmanufacturerofvideogames.HestruckafriendshipwithfellowdesignerSteveWozniakandattendedmeetingsofthe“HomebrewComputerClub”withhim.In1976,heco-foundedAppleComputerinhisfamilygarage.HebecamethepermanentCEOfromtheyear2000,onwardshespearheadtheadventoftheiMac,iTunes,iPod,iPhone,andiPad.OnOctober5,2011,hepassedaway.ClassActivities44HewasbornonMay14,1984.HeisanAmericancomputerprogrammerandInternetentrepreneur.Heisbestknownforco-creatingthesocialnetworkingsiteFacebook,ofwhichheischiefexecutiveandpresident.Heco-foundedaprivatecompanyin2004whileheisastudentatHarvardUniversity.In2010,hewasnamedTimemagazine'sPersonoftheYear.ClassActivitiesUnit2ComputerHardwarenewemployeeorientationintroductionofcomputerhardwarePCportsthehistoryofAppleproductstipsonhowtobuildyourownPCProfessionalTerminology:hardware;software;printer;copymachine;systemunit;screen;monitor;speaker;keyboard;mouse;microphone;peripheraldevice;diskdrive;harddrive;randomaccessmemory(RAM);CPU(CentralProcessingUnit);functionkey;navigationkey;numerickeypad;tabletcomputerOutline：FirstDayatWork

Hello,Mr.Lee.I’mJessieStevens.Thereceptionisttoldmetocomeseeyoufirst.Welcomeaboard,Jessie.Wearegladthatyouwillbeworkingwithus.

WhatdoIneedtodotogetstarted?

Well,we’vegotsomepaperworkforyoutofillout.

FirstDayatWork

Sure.WherecanIfillitout?Comeonover.Thisisyourdeskandyourpersonalcomputer,whichisconnectedtotheprinteratthecorner.Youcanalsousethescannerandthecopymachineoverthere.Doeseverythingonthisdeskbelongtome?

Notbelong.Youcanusethemaslongasyouworkhere.Whenyouquit,you'llhavetoreturnthemtothecompany.

FirstDayatWork

Iwillcertainlydo.IsthecomputerconnectedtotheInternet?

Yes,itisalsoconnectedtothecorporateintranet.Thisisyourtimecard.Besuretoclockinandoutbeforeandafteryouwork.Whenyousettledown,I'llshowyouaroundandintroduceyoutothedepartmentmanagers.

Thanksalot.TextA:GettoKnowYourPersonalComputer

YourPC(PersonalComputer)isasystem,consistingofmanycomponents.Someofthosecomponents,likeWindowsXP,andallyourotherprograms,aresoftware.Thestuffyoucanactuallyseeandtouch,andwouldlikelybreakifyouthrewitoutafifth-storywindow,is,hardware.

TextA:GettoKnowYourPersonalComputerNoteverybodyhasexactlythesamehardware.Butthoseofyouwhohaveadesktopsystem,liketheexampleshowninFigure1,probablyhavemostofthecomponentsshowninthatsamefigure.Thoseofyouwithnotebookcomputersprobablyhavemostofthesamecomponents.Onlyinyourcasethecomponentsareallintegratedintoasinglebook-sizedportableunit.

TextA:GettoKnowYourPersonalComputerThesystemunitistheactualcomputer;everythingelseiscalledaperipheraldevice.Yourcomputer'ssystemunitprobablyhasatleastonefloppydiskdrive,andoneCDorDVDdrive,intowhichyoucaninsertfloppydisksandCDs.There'sanotherdiskdrive,calledtheharddiskinsidethesystemunit,asshowninFigure2.Youcan'tremovethatdisk,orevenseeit.Butit'sthere.Andeverythingthat'scurrently"inyourcomputer"isactuallystoredonthatharddisk.(Weknowthisbecausethereisnoplaceelseinsidethecomputerwhereyoucanstoreinformation!).

TextA:GettoKnowYourPersonalComputerTextA:GettoKnowYourPersonalComputer

ThefloppydriveandCDdriveareoftenreferredtoasdriveswithremovablemediaorremovabledrivesforshort,becauseyoucanremovewhateverdiskiscurrentlyinthedrive,andreplaceitwithanother.Yourcomputer'sharddiskcanstoreasmuchinformationastensofthousandsoffloppydisks,sodon'tworryaboutrunningoutofspaceonyourharddiskanytimesoon.Asarule,youwanttostoreeverythingyoucreateordownloadonyourharddisk.UsethefloppydisksandCDstosendcopiesoffilesthroughthemail,ortomakebackupcopiesofimportantitems.TextA:GettoKnowYourPersonalComputerThere'stoomuch"stuff"onyourcomputer'sharddisktouseitallatthesametime.Duringtheaveragesessionsittingatthecomputer,you'llprobablyuseonlyasmallamountofallthat'savailable.Thestuffyou'reworkingwithatanygivenmomentisstoredinrandomaccessmemory(oftenabbreviatedRAM,andoftencalledsimply"memory").TheadvantageusingRAMtostorewhateveryou'reworkingonatthemomentisthatRAMisveryfast.Muchfasterthananydisk.Foryou,"fast"translatestolesstimewaitingandmoretimebeingproductive.

RandomAccessMemory(RAM)TextA:GettoKnowYourPersonalComputerSoifRAMissofast,whynotputeverythinginit?Whyhaveaharddiskatall?TheanswertothatliesinthefactthatRAMisvolatile.Assoonasthecomputerisshutoff,whetherintentionallyorbyanaccidentalpoweroutage,everythinginRAMdisappears,justasquicklyasalightbulbgoesoutwhentheplugispulled.Soyoudon'twanttorelyonRAMtoholdeverything.Adisk,ontheotherhand,holdsitsinformationwhetherthepowerisonoroff.

TextA:WhatisHardware?

Alloftheinformationthat's"inyourcomputer",sotospeak,isstoredonyourcomputer'sharddisk.Youneverseethatactualharddiskbecauseit'ssealedinsideaspecialhousingandneedstostaythatway.UnlikeRAM,whichisvolatile,theharddiskcanholdinformationforever--withorwithoutelectricity.Mostmodernha