01-04-2020-Oxford_English_for_Infomation_Technology (1171844), страница 11
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In our bouncing ballexample, in a B-frame the picture is stored as thedifference between the previous I or P-frame andthe B-frame and as the difference between the Bframe and the following I or P-frame. To recreatethe B-frame when playing back the sequence, theMPEG algorithm uses a combination of tworeferences. There may be a number of B-framesbetween I or P-frames. No other frame is everbased on a B-frame so they don't propagate errorslike P-frames.Typically, you will have two or three Bs betweenIs or Ps, and perhaps three to five P-framesbetween Is.[Adapted from 'The Tricks to MPEG's Success', WindowsMagazine, March 1994]BRe-read the text to find the answers tothese questions.1 Mark the following statements as True orFalse:aJPEG is the most common compressionsystem used for video.b P-frames only store the changes in theimage.c There is always at least one P-framebetween two I-frames.d B-frames store the complete pictureinformation.e There can only be one B-frame between eachI and P-frame.f There are typically about four P-framesbetween each I-frame.2 Match the words in Table A with thestatements in Table B.Table Aa Algorithmb I-framec JPEGd P-framee B-framef MPEGTable Bi A common type of compression used forvideo dataii A compressed video frame known as apredicted frameiii A compressed video frame that storeschanges between the frame before it andthe frame after it.iv A formula used for decompressingcomponents of a data streamv A type of compression used for bitmapimagesvi A compressed video frame that containsthe complete image informationUNIT 10INTERVIEWComputing Support OfficerSTARTERStudy this screen display of Windows Explorer.
Add thesetitles to the texts:Toggle-boxExplorer paneSelected iconDividerGuidelinesNavigation paneDesktopWindows Explorer isjust a different viewof the structure,with the desktop atthe top and filteringdown through MyComputer to yourhard drive.View menuJust like desktopwindows, your viewof the files andfolders can bechanged here. Thedefault (standard)view is List, but usethe one you findcomfortable.Indicates that thedrive or foldercarries sub-folders.Use theseto open or close'branches'in thefolder hierarchy.dTheworks in the sameway as the desktopwindows you'vebeen using. Doubleclicking on a folderopens the branchesleading to it in thenavigation pane.These handyhelp youto see which folderslive at the samelevel. It also makesit easier toappreciate the treelike structure youare dealing with.You can tell which folder is currentlybeing displayed by the icon.
Driveswill have their text highlighted,whereas folders are 'open' - click onone and try it.This shows only drives and folders in other words, items that containsomething else. To view the fullcontents of a folder, click on its iconin theYou can adjust thespace allocated toeach pane byclicking on anddragging the- handywhen the foldertree starts to sprawl.Fig 1Windows ExplorerLISTENINGBarbara is a Computing Support Officer in a largecompany. She's advising Clive, the Sales Director.
Listen to Part 1 ofthe recording to find the answers to these questions:1 What is dive's problem?2 What does he want to do?These screen displays show some of the steps inBarbara's explanation. Listen to Part 2 of the recording and put themin the correct sequence.Fig 24 screen displaysListen to Part 3 to answer these questions:12345What additional task does Clive need help with?What indication is there that Contract now contains subfolders?What are the subfolders called?What operation is used to move files into the new subfolders?What does Barbara refer to as a 'handy tool'?70 UNIT 10 Computing Support OfficerLANGUAGE WORKRevision: if-sentencesStudy these uses of if-sentences.Action and effectWe can use an if-sentence to link an actionand its effect.
For example:1If you click on that [action], that'll justcompact your C drive [effect].2 If you click on that [action], that opens it upand shows you all your folders [effect].The action is in the Present simple and theeffect is in the Present simple or describedusing will, can, or may depending howcertain it is to follow.Polite instructionsImagined action and effectWe can use an if-sentence to describe thepossible effect of an imagined action. Forexample:5 If you spilled coffee on your keyboard[imagined action], you could damage it[possible effect].6 If there were no other folders there[imagined action], you wouldn't have alittle box in there [possible effect].To show this describes imagined, not real,events, the action is in the Past simple andthe effect is described using would, could,and might depending how certain it is tofollow.We use the action part of if-sentences,especially in spoken English, to giveinstructions in a polite way.
The effect part isassumed.3If you bring your cursor down to the verybottom [you'// find the Start button].4 If you just hit Enter [that will activate theprogram].Match the actions in Column A with appropriate effects fromColumn B. Then join each action and effect using an if-sentence.Column AColumn B1you press Print Screenayou can drag it across the screenyou press Ctrl + Alt + Del in Windowsbit would speed up the computercyou may lose datadyou would have more space at yourdeskeyou would be able to connect to atelephone linefyou can make a copy of the screen2983you added more memory4you installed a modem5you used a better search engine6you forget to save regularly7you hold down the mouse button overan icon8you used an LCD displaygyou would find more relevant resultshit displays a list of active programsUNIT 10 Computing Support OfficerDescribe the effects of these actions using an if-sentence.12345678WORD STUDYyou don't virus-check floppiesthere was a power cut while you were using your computeryou install a faster processoryou forgot your passwordyou press the delete keyyou use a search engineyou double-click on an iconyou use power-saving optionsNoun + Noun compounds Match each word from Column Awith its partner from Column B to make a computing term.
All theseterms are from previous units.Column ASPEAKINGColumn BbarcodetraymainframeprogramlaserbusexpansionpanefloppycomputercontrolreadersupervisorbartaskcardsystemdriveexplorerprinterWork in pairs, A and B. Instruct each other how to performthese computer operations in Windows or Mac OS. Take notes fromyour partner's instructions.Student AStudent BCopying a file.Saving a file.71With the help of this diagram, try to describe the function ofthese components of a typical network system:STARTER1 a file server2 a bridge3 a router4 a backbone567a LANa gatewaya modemInternetRouterAnother Novell LANBridgeFibre-opticbackboneShared hard diskBridgeShared network printerGatewayUnix networkTwisted pair cablingComputers withnetwork interface cardsLocal printerFig 1Components of a typical LANNow read these definitions to check your answers.
You mayalso refer to the Glossary.A bridge is a hardware and softwarecombination used to connectthe same type of networks.Bridges can also partition alarge network into two smallerones and connect two LANsthat are nearby each other.A router is a special computer thatdirects communicatingmessages when severalnetworks are connectedtogether. High-speed routerscan serve as part of theInternet backbone.A gateway is an interface thatenables dissimilar networks tocommunicate, such as twoLANs based on differenttopologies or networkoperating systems.A backbone is the main transmissionpath, handling the major datatraffic, connecting differentLANs together.A LAN is a network contained withina small area, for example acompany department.A modem is a device for convertingdigital signals to analoguesignals and vice versa toenable a computer to transmitand receive data using anordinary telephone line.READINGNow study this text and the diagram of a simple home networksetup.
Match the diagram key to the components of the network.The technology needed to set up ahome network is here today. It isjust a matter of connecting anumber of PCs equipped withEthernet adapters to a hub usingtwisted-pair cabling which usessockets rather like phone sockets.Special isolation adapters can befitted to allow existing mains linesto be used instead of twisted-paircabling. Most future homenetworks, however, are likely to bewireless network systems, usingtuned transmitter and receiverdevices. The simplest networksallow basic file-sharing and multi-player gaming as well as sharing ofperipherals such as printers. Mostadvanced home networks arelikely to have a client/serverstructure, with low-cost terminals,or 'thin' clients, connected to acentral server which maintains thesystem's storage capacity and,depending on whether theterminals are dumb or processorequipped network computers, itsprocessing power.
To make themost of such a network, it mustbecome part of an integratedhome entertainment and controlsystem. To the user, the desktopbecomes just one of many featuresaccessible throughout the house.Tired of working in the study?Pop down to the living room andreload it into the terminal there.Before you start work, call up thehi-fi control program and havethe music of your choice pumpedthrough the living room speakers.Computer and entertainmentnetworks can be separate butlinked by the server to allowcontrol of the latter from theterminals. Future home networksare more likely to have the entiresystem based on a single loop.KEY TO THE DIAGRAMFig 2Simple home network74UNIT 11 NetworksLANGUAGE WORKlative clauses with a participleRelative clauses with a participle are oftenused in technical descriptions.
They allowyou to provide a lot of information about anoun using as few words as possible.Study these examples from the Task 3 text.1 The technology needed to set up a homenetwork2 PCs equipped with Ethernet adapters3 Network modem allowing clients to accessthe Internet simultaneously4 Data line linking client to serverWe can use the passive participle as inexamples 1 and 2.1 The technology needed to set up a homenetwork.= technology which is needed2 PCs equipped with Ethernet adapters= PCs which are equippedWe can use an active participle as inexamples 3 and 4.3Network modem allowing clients to accessthe Internet simultaneously= modem which allows clients to access theInternet simultaneously4 Data line linking client to server= data line which links client to serverComplete these definitions with the correct participle of theverb given in brackets.12345678910A gateway is an interface (enable) dissimilar networks tocommunicate.A bridge is a hardware and software combination (use) toconnect the same type of networks.A backbone is a network transmission path (handle) major datatraffic.A router is a special computer (direct) messages when severalnetworks are linked.A network is a number of computers and peripherals (link)together.A LAN is a network (connect) computers over a small distancesuch as within a company.A server is a powerful computer (store) many programs (share)by all the clients in the network.A client is a network computer (use) for accessing a service on aserver.A thin client is a simple computer (comprise) a processor andmemory, display, keyboard, mouse and hard drives only.A hub is an electronic device (connect) all the data cabling in anetwork.UNIT 11 Networks75Link these statements using a relative clause with a participle.a The technology is here today.b It is needed to set up a home network.a You only need one network printer.b It is connected to the server.a Her house has a network.b It allows basic file-sharing and multi-player gaming.a There is a line receiver in the living room.b It delivers home entertainment audio to speakers.a Eve has designed a site.b It is dedicated to dance.a She has built in links.b They connect her site to other dance sites.a She created the site using a program called NetscapeComposer.b It is contained in Netscape Communicator.a At the centre of France Telecom's home of tomorrow is anetwork.b It is accessed through a Palm Pilot-style control pad.a The network can simulate the owner's presence.b This makes sure vital tasks are carried out in her absence.a The house has an electronic door-keeper.b It is programmed to recognise you.c This gives access to family only.PROBLEM-SOLVINGGroup AWork in two groups, A and B.
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