计算机原理 - 输入设备与接口

InputDevicesChapter20OverviewInthischapter,youwilllearnhowtoExplainhowtosupportcommoninput/outputportsIdentifycertainstandardinputdevices

onaPCDescribehowcertainmultimediainputdevicesworkonaPCSupportingCommonPortsSerialUSBFireWireSerialPortsConvertdatabetweenserialandparalleldevicesRS-232StandardPrimarystandardusedfor

serialdevicesRarelyusedtodayinPCsOtherstandards(suchas

USB)aremuchquickerCOMportsareserial9-pinconnectorUsedbymodemsandotherdevicesFigure1:SerialportSerialPortPropertiesSpeedsetinbitspersecond75bpsto128,000bps9600bpscommonfor

devicesotherthan

modemsUseDeviceManagerSizeofdata

chunkssentis

7or8bitsStopbitsIdentifyendofchunkFlowcontrolFigure2:SerialportsettingsSerialPortProperties(continued)Figure3:SerialportinstructionsUSBPortsUnderstandingUSBHostcontroller(ofteninchipset)containsroothubRoothubislikean

expansionbusAlltheUSBdevices

connecttotheroot

hubportsAlldevicessharethe

samebandwidthThemoredevicesyouhaveonasingleUSBhostcontroller,theslowertheyrunFigure4:Hostcontroller,roothub,andUSBportsUSB1.1and2.0SpeedsUSB1.1—firstwidelyadoptedstandard1.5Mbps(Low-Speed)12Mbps(Full-Speed)USB2.0—backward-compatible480Mbps(Hi-Speed)TogetHi-SpeedHi-Speeddevicemustbepluggedinto

Hi-SpeedportSpeedistotalspeedofbusDividedamongallthedevicesMostsystemssupportboth1.1and2.0USB1.1and2.0(continued)Figure5:USBadaptercardFigure6:SharedUSBportsUSB3.0USB3.0CalledSuperSpeedUSBThroughputspeedsupto5GbpsDevicesshowingupin2010Connectorsdiffer,butprovidebackwardcompatibilitywitholderUSBstandardsUSB2.0cableswillplugintoUSB3.0devicesAlldeviceswillrunatUSB2.0speedsUSB3.0cableswillnotfitintoprior-version

USBdevicesUSB3.0cablesrequiredforthehigherspeedPortsareseparateandclearlymarkedasUSB3.0,usuallycoloredblueUSB3.0(continued)Figure7:USB3.0portsFigure8:USB3.0cableUSBHubsandCablesUSBcontrollertheoreticallysupportsupto127devices—butthatisnotpracticalintherealworldAddhubstoaddadditionalportsHubscanbepoweredorunpoweredUSB1.1and2cablescan’tbelongerthan5meters—USB3doesnothavethisrestrictionUSBHubsandCables(continued)USBconnectorsandportscomeinmultiplesizes:A,B,mini-A,mini-B,micro-A,andmicro-BUSBAportsandconnectorsareforinterfacingwiththePCMostperipheralsuseB,mini-B,ormicro-BconnectorsandportsMicroconnectionsareespeciallypopularonsmartphonesUSBHubsandCables(continued)Figure9:USBcableFigure10:USBhubFigure11:USBkeyboardwithbuilt-inhubUSBConfigurationWindowshasalargenumberofbuilt-indriversforUSBdevicesFirstruleofUSBdeviceinstallationInstalldriverBEFOREinstallingdevice–exception:USBthumbdrivesDeviceManagerprovidesmanydetailson

USBdevicesFigure12:WindowsXPspeedwarningUSBConfiguration(continued)DeviceManagershowsallUSBdevicesLocateUSBhubunderUniversalSerialBusControllericonHasaPowertabtoshowpowerproperties

BewareofsleepingdevicesSystemtellsthemtosleeptosavepowerSleepingdevicesnolongerappearin

DeviceManagerMightnotwakeupUSBConfiguration(continued)Figure13:USBhubPowertabFigure14:Generalpurposebus-poweredhubFigure15:PowerManagementtabLab–WakeitupGotoDeviceManager

ScrolldowntoUniversalSerialBusControllersClickonthe“+”toexpand

Right-clickanyUSBRootHubandselect

Properties

ClickPower

Managementtab

DeselectAllow

thiscomputerto

turnoffthis

devicetosave

powerIEEE1394(FireWire)SimilartoUSBDifferentspeedsanddifferentconnectorsIEEE13941394arunsat400Mbps1394brunsat800Mbps6-pinpoweredconnector4-pin(unpowered)connector9-pin1394bconnectorFireWireDevicescanbeconnectedtoahub

ordaisy-chainedUpto63devices

supportedMaxcablelength

canbeupto

4.5metersCannetworktwo

computersin

Windows2000/XP,

butnotVistaFigure16:Hubbedversusdaisy-chainconnectionsGeneralPortIssuesUseHardwareRemovalToolBasicchecksIstheportbadoristhedevicebad?Pluginknown-gooddeviceto

checkportPlugintoanotherportonthemotherboardIfportisbadCheckCMOS—turnedoff?CheckDeviceManagerfor

disableddevicesFigure17:DisabledparallelportinDeviceManagerinbothVistaandXPGeneralPortIssuesCheckforphysicaldamageBent,missingpinsSometimespossibletoreshapepinsandplugsFigure18:BrokenUSBportFigure19:BadlybentPS/2plugCommonStandardInputDevices

Keyboards

Mice

Scanners

Digitalcameras

WebcamerasBiometricDevicesPrimarymethodofinputUSBkeyboardsMakesureUSBKeyboardSupportOptionisenabled

inCMOSSomesettingsareavailable

inKeyboardapplet

(Windows2000/XP)Personalizationapplet

(WindowsVista)offers

extrasettingsEaseofAccessKeyboardsFigure20:CMOSUSBKeyboardSupportoptionKeyboards(continued)Figure21:KeyboardControlPanelappletCleaningtheKeyboardCleanthetopwithclothdampened

withwater

Canuseisopropylalcohol

forstubborndirt

Poweroffbeforecleaning!Figure22:CleaningkeysCleaningtheKeyboard(continued)CleaningunderthekeysStartwithcompressedairCansometimestakethelayersapartandcleanKeeptrackofthelocationofallkeysandpartsAllowsheetstodrybeforereassemblingCarefulwhenremovingkeys—canbreakthemCleaningtheKeyboard(continued)Figure23:SeriouskeyboardsurgeryFigure24:PryingoffakeyMiceHotkeysenableyoutoworkwithout

amouseinWindowsMouseappletinControlPanelFigure25:MouseControlPanelappletMice(continued)TwoprimarytechnologiesBallmice—usesmallroundballOpticalmice—useLEDsorlasersCommonproblemwithballmiceTheygetdirtyMousepointerbecomesjumpyOpticalmicepreferredBallmouseRemovetheballandwash

withsoapandwaterDrycompletelybeforereturning

tothemouseRemovedirtfromrollerOpticalmouseRarelyneedcleaningCleanopticswhennecessaryCleaningtheMouseCleaningtheMouse(continued)Figure26:RemovingthecollaronaballmouseFigure27:CleaningtherollersonaballmouseFigure28:CleaninganopticalmouseScannersEnableyoutomakedigitalcopiesofPhotosDocumentsDrawingsNegativesCanenableoptical

characterrecognition(OCR)FlatbedscannersPlacedocumentontheglassClosethelidRunthesoftwareFigure29:ScanneropenwithphotographfacedownScanners(continued)SoftwareusedtocaptureimageDefaultdriverTWAIN(TechnologyWithoutAnInterestingName)CommonsoftwareScanner-specificGnuImageManipulationProgram(GIMP)Figure30:EpsonsoftwarewithPhotoshopopeninthebackgroundScanners(continued)Figure31:AcquiringanimageinGNUImageManipulationProgramHowtoChooseaScannerConsiderfiveprimaryvariablesResolution—dotsperinch(dpi)Colordepth—bitsusedforcolor(8,16,24,36,

42,48)Grayscaledepth—bitsforshadesofgray(8,16,more)Connection—typicallyUSBorFireWireScanspeed—secondsHowtoChooseaScanner(continued)Figure32:Earringscannedat72dpiand24-bitcolorFigure33:Sameearring,scannedat300dpiand24-bitcolorFigure34:Sameearring,scannedat1200dpiand24-bitcolorInstallingandScanningTipsScannersuseUSBorFireWireconnectionstoday—olderonesuseSCSIorparallelInstalldriversbeforeplugginginDothebestqualitypossiblefirstThenmanipulatesizeandqualityforenduseTworesourcesaffectwhatyoucandoRAM:8x10@600dpiisabout93MBProcessorspeedInstallingandScanningTips(continued)WatchoutfortheLockingBar!Allscannershavealockforthescanningmechanismtoprotectitduringamovefromonelocationtoanother.Ifyouhavearecentlymovedscannerthatwon’tscan,checkthelock.Unlockasnecessary

Anexcellentsiteforscannerinformation(forinstance,ifyou’recreatingfamilyarchives)

UsedforauthenticationorrecognitionFingerprintscannersRetinalscannersVoicerecognitionBiometricDevicesFigure35:USBthumbdrivewithfingerprintscanner(photocourtesyofLexarMedia,Inc.)Figure36:MicrosoftfingerprintscanneronakeyboardBiometricDevices(continued)Biometricdevicesdon’treplacepasswordsAllbiometricdevicesrequiretrainingVoicerecognitiondevices,forexample,requirethatyouspendalotoftimegettingthesoftwaretounderstandyourvoiceInstallingInstallthedevice(driverfirst,thenUSBdevice)Registeryouridentity(insertbodyparthere)ConfigurethesoftwaretotellthedevicewhattodowhenitrecognizesyouDesignedtoreadstandardUniversalProductCode(UPC)FrequentlyusedtotrackinventoryIncludesassetinventoryAlsousedinpoint-of-salesystemsConnectorsPS/2USBBarCodeReadersFigure37:Typical

UPCcodeFigure38:Penscanner(photocourtesyof

Wasp®BarcodeTechnologies)TouchScreensAmonitorwithasensingdeviceon

itsfaceDetectslocationoftouchEitherbyfingerorstylusRespondsasifitwereamouseclickTouchscreenscanbeseeninInformationkiosksSmartphonesPoint-of-salesystemsTabletsKVMKeyboard,video,mouse(KVM)switchEnablesyoutoconnectmultiplecomputerstoasinglekeyboard,video,andmouseUsefulwhenspaceislimitedFigure39:Atypical

KVMswitchGamepadsandJoysticksTwoperipheralsarecommonlyusedforcontrollingPCgames:joysticksandgamepadsGamesthatusejoystickshavedeclinedinpopularityMostmodernPCgamesarecontrolledbymouseandkeyboardFigure40:AjoystickFigure41:AgamepadGamepadsandJoysticks(continued)SomePCgames,especiallythosethatweredesignedtoplayedongamingconsoles,arebestenjoyedwhenusingagamepadAgamepadlooksmorelikeastandardvideogamecontroller,usuallycoveredinanarrayofbuttonsandtriggersJoysticksandgamepadspreviouslyusedaspecialjoystickconnector;nowtheyuseUSBMayrequireadditionalorspecificdriversGamepadsandJoysticks(continued)InWindowsXPandVista,theycanbeconfiguredusingtheGameControllersControlPanelappletInWindows7,opentheStartmenuandselectDevicesandPrinters.Right-clickonthecontrollerandselectGamecontrollersettingsGamepadsandJoysticks(continued)Figure42:GamecontrollerpropertiesDigitizersAdigitizer(otherwiseknownasapentablet)enablesuserstopaint,ink,pencil,orotherwisedrawonacomputerReceivesinputusingaspecialsurfaceMostdigitizersconnecttoyourPCviaaUSBconnectionShouldincludebothdriversandaconfigurationutilitySomemayrequirespecificgraphicssoftware

tofunctionDigitizers(continued)Figure43:AtypeofdigitizerknownastheWacompentabletFigure44:DrawingwithadigitizerMultimediaDevicesDigitalCamerasStoragemedia—digitalfilmMostdevicesusearemovablestoragemediainsteadoffilmUsuallyaSecureDigital(SD)cardUsuallyrangeincapacityfrom1GBto32GBSomecamerashavebuilt-inharddrivesforlargercapacityConnectionMostdigitalcamerasplugdirectlyintoaUSBportAnothercommonoptionistoconnectonlythecamera’sstoragemediatothecomputer,usingabuilt-inorexternaldigitalmediareader—mostreaderscanhandlemultipleformatsDigitalCameras(continued)Figure45:SecureDigitalcardFigure46:CameraconnectingtoUSBportDigitalCameras(continued)QualityUsuallyexpressedassomenumberofmegapixelsRangefrom1megapixel(older)tonewer5,10,andhighermegapixelsChooseopticalzoom(builtintothecameralens)overdigitalzoom(usessoftwarebuiltintothecamera)wheneverpossibleforbetterqualityFormfactorComeinmanysizesandshapesBiggerisusuallybetterintermsofqualityandfeaturesDigitalCameras(continued)Formfactors(continued)DigitalSLR(high-qualitylens,CCDs/CMOSsensors,andflash;plushaveinterchangeableparts)SuperZoom(likeSLR,butsmallerandusuallyfixed)Mid-sizedPocket-sizedSensorsmatterBiggerisalmostalwaysbetterCCD(charge-coupleddevice)CMOS(complimentarymetal-oxidesemiconductor)DigitalCameras(continued)Figure48:TypicaldigitalcamerasFigure49:DigitalcamcordersWebCamerasPCcamerasareoftencalledwebcamsbecausetheirmostcommonuseisforInternetvideocommunication.Imagequalityisthebiggestissuewithwebcams.Webcamsmeasuretheirresolutioninpixels,justlikedigitalcameras.Webcamscanhavefromasfewas100,000pixelsuptomillionsofpixels.Aswithdigitalcameras,ahighernumberofmegapixelsisusuallybetter—uptoapoint.WebCameras(continued)Figure50:VideochattingbywebcamwithSkypeWebCameras(continued)Imagequality(