计算机专业英语.ppt

7.1.4LocalAreaNetworkContentsfigure7-7OnanEthernet，apacketisacceptedonlybythedevicetowhichitisaddressedAbasicEthernetnetworkrequiresanEthernetcardineachworkstationandanyperipheraldeviceattacheddirectlytothenetwork.AnEthernetcardisatypeofnetworkinterfacecard(NIC）,ornetworkadapter,designedtosupportEthernetprotocol.Manydesktop,notebook,andtabletcomputerincludeapreinstalledEthernetcard.Ethernetcircuitryisalsoincludedinsomeprintersandotherperipheraldevices.

一个基本的以太网网络需要一个以太网卡在每个工作站和外围设备直接连接网络。以太网卡是一种的网络接口卡(NIC)、或网络适配器,它被设计用来支持以太网协议。许多台式机,笔记本,包括平板电脑都预装以太网卡。以太网线路还包括在有些打印机及其他周边设备。
Add-onEthernetcardsfordesktopcomputersfitintoaslotinsidethesystemunit.Add-onEthernetcardsfornotebookandtabletcomputersaredesignedtofitinaPCMCIAslot,Thecostofadd-onEthernetcards,suchasthoseshowninFigure7-8,canbeaslowas$15.

附加式以太网卡放入台式电脑的主板插槽。附加式以太网卡为笔记本电脑和平板电脑设计,放进一个PCMCIA插槽,附加式以太网卡的价格可以低至15美元,如那些如图7-8,。
Wi-Fi(WirelessFidelity)referstoasetofwirelessnetworkingtechnologiesdefinedbyIEEE802.11standardsthatarecompatiblewithEthernet.AWi-Finetworktransmitsdataasradiowavesoverpredefinedfrequencies,muchlikecordlesstelephone.

WiFi(无线保真)指的是一套符合IEEE802.11以太网无线网络技术标准规定。一个无线网络传送数据的无线电波频率使用的是预定义的频率,就像无绳电话。ThebigattractionofWi-Fiistheabsenceofwiresandcablesrunningthroughwallsandbetweenfloors.Wirelessnetworkareespeciallydesirablefornotebookandtabletcomputersthatdon'totherwiseneedtobetetheredtoelectricaloutletsfortrueportability.
Wifi的巨大吸引力是墙壁和地板没有电线电缆贯穿之间。无线网络特别称心的是体现在笔记本和平板电脑,它真正的便携性使得我们不需要被系在电子插座旁。AswithawiredEthernetnetwork,everyworkstationandnetworkperipheralrequiresanetworkinterfacecard.AWi-Fiacardincludesatransmitter,receiver,andantennatotransmitsignals.Wi-FicardsfornotebookortabletcomputerscanplugintoaPCMCIAslotorUSBport.Wi-FicapabilitycanbeaddedtoadesktopcomputerasaWi-FicardthatfitsintoasystemunitslotwiththeantennaprotrudingoutofthebackorasasmallboxthatconnectstoaUSBport.YetanotheroptionistouseawirelessadaptertoconvertastandardEthernetportintoawirelessFigure7-9illustratesvariousWi-Ficards.

正如一个有线以太网网络，