94696

DATA COMMUNICATION SYSTEMS

Конспект урока

Иностранные языки, филология и лингвистика

Would you associate them with e-mail the Internet or both If there any words you don’t know find someone in the class who can explain them to you. In the early 90s the dawn of history as far as the World Wide Web is concerned relatively few users were communicating across this global network.

Английский

2015-09-15

135 KB

0 чел.

105

UNIT VIII

DATA COMMUNICATION SYSTEMS

INTRODUCTORY TEXT

                                                             A multi-user system is made up of a number

                                       of terminals sharing a mainframe computer. Each

                                       terminal consists of at least one input device and output device and allows the user to communicate with the computer.

There are a number of different types of terminals. For example, a teletype terminal is made up of a keyboard and a printer which gives a hardcopy output.

A VDU terminal has a keyboard and a screen. It usually has its own internal processor which deals with the input/output and editing of data and is, therefore, referred to as an intelligent terminal.

A graphics terminal is similar to a VDU terminal but is specially designed to display graphics such as pictures, maps, graphs, diagrams etc. and has a lightpen attached to allow the user to ‘draw’ on the screen. It is normally used for Computer Aided Design.

Often a mainframe computer and its terminals are situated a long distance apart. They may be in different rooms, buildings, cities or even countries. These remote access terminals are connected to the mainframe computer by telecommunication links (e.g. telephone lines). Computers and terminals connected together  using telecommunications are known as a data communications (or datacomm) system.

Datacomm systems may also be formed from a number of computers and peripherals connected together in a network. This allows software and hardware to be shared by a large number of users over long distances.

A network contained in a relatively small area, such as an office building, factory site or university campus, is known as a Local Area Network or LAN. The two main types of LAN are single cable networks and loop networks.

If the network is connected over a large area  it is called a Wide Area Network or WAN. This may be linked using telephone lines. Dedicated lines are permanently connected to a system but dialed lines are only connected when needed. However, existing telephone lines are designed to carry analogue signals and not the digital signals used by computers. A special device is therefore needed at each end of the telephone line to convert the signals to the correct form. This device is known as a modulator/demodulator or modem. A special kind of modem known as an acoustic coupler has rubber cups into which an ordinary telephone can be plugged.  Although this avoids having to make a special connection into the telephone system, it is more likely to suffer from corruption of data due to interference.

Modern telecommunications systems are being developed using fibre-optic cables. These allow data to be transmitted as pulses of light along thin strands of glass (about the thickness of a human hair). In this way, data can be communicated at very high speed, measured in bauds i.e. bits per second. It also results in very low level of interference.

Data can be communicated over long distances and over water by using microwave radio links. These transmit and receive high frequency microwave signals using small dish aerials. Since there must be a clear path between these aerials, they are usually situated at the top of high towers.

Data communications over long distances can make use of communications satellites, which are placed in fixed orbits above the Earth. The satellites receive signals from ground stations on the Earth, amplify the signals then retransmit them to other ground stations, which may be in another country or another continent.

The development of efficient data communications systems is an important aspect of the growth in information technology.

TOPICAL VOCABULARY

  1.  apart                             отдельно, порознь
  2.  remote access                   дистанционный доступ, выборка
  3.  single cable network        однокабельная сеть
  4.  loop network                    разветвленная сеть
  5.  dedicated line                   специализированная линия
  6.  dialed line                         автоматическая линия, соединенная с

                                             компьютером когда требуется

  1.  acoustic coupler               акустический коммутатор
  2.  plug                                  вставлять штепсель (программная

                                            вставка)

  1.  fibre-optic cable               оптоволоконный кабель
  2.  strand                           прядь, стренга
  3.  baud                             бод (единица скорости передачи

                                            информации)

  1.  aerial                            антенна
  2.  amplify                        расширять, усиливать
  3.  wave                            волна

EXERCISES

  1.  Read the introductory text and answer the following questions.
  •  What is meant by the word ‘terminal’? What types of terminal do you know?
  •  Can you explain the meaning of the abbreviations LAN and WAN? Give the answer.
  •  What device is used to connect a computer to a telephone line?
  •  Is there any difference between dedicated and dialed line?
  •  Is using telephone lines the only way of transmitting data? If not, name other means.
  •  Which type of cable allows data to be transmitted as pulses of light?
  •  How can you express the key idea of the text?

  1.  Complete the tables.  

Table 1.

Terminal

Components

Features

Teletype

VDU

Graphics

                                      

Table 2.

Datacomm system

Components

Functions

1. Network

2. LAN

3. WAN

4. Modem

5. Fibre-obtics cable

6. Microwave radio

7. Communications satellite

3. Compare some things given below showing their similarity and contrast. Use the following expressions:

Like…                                        Both…           

Unlike…                                    …is different to…

In comparison with…                …,whereas…

        In contrast to…                         …is similar to…                        

 

  •  Dialed line, dedicated line  
  •  Analogue signal, digital signal    
  •  Local Area Network, Wide Area Network
  •  Ordinary telephone cable, fibre-obtics cable   
  •  Microwave radio link, satellite link
  •  Input device, output device
  •  Impact printer, non-impact printer

  1.  Look at the words  and phrases in the box. Would you associate them with e-mail, the Internet or both? If there any words you don’t know , find someone in the class who can explain them to you.

               

  •  Work with a partner. Choose three of the words from the box and write definitions for them. Close your books and exchange your definitions with another pair of students. Can you remember the terms?

  1.  Read the text and do the tasks given below.

INTERNET EXPLORER HISTORY

In the early 90s—the dawn of history as far as the World Wide Web is concerned—relatively few users were communicating across this global network. In 1995, Microsoft hosted an Internet Strategy Day and announced its commitment to adding Internet capabilities to all its products. In fulfillment of that announcement, Microsoft Internet Explorer arrived as both a graphical Web browser and the name for a set of technologies.

1995: Internet Explorer 1.0

In July 1995, Microsoft released the Windows 95 operating system, which included built-in support for dial-up networking and TCP/IP (Transmission Control Protocol/Internet Protocol), key technologies for connecting to the Internet. In response to the growing public interest in the Internet, Microsoft created an add-on to the operating system called Internet Explorer 1.0. When Windows 95 with Internet Explorer debuted, the Internet became much more accessible for many more people.

For Windows 95 Internet Explorer replaced the need for cumbersome, manual installation steps required by many of the existing shareware browsers.

1995: Internet Explorer 2.0

In November 1995, Microsoft released its first cross-platform browser, Internet Explorer 2.0, which supported both Macintosh and 32-bit Windows users.

With Internet Explorer 2.0 came a new set of fledgling Internet technologies that offered Web developers and designers the power to design secure, media-rich Web sites with tracking capabilties. Internet Explorer 2.0 technology introduced Secure Socket Layer (SSL) protocol as well as support for HTTP cookies, Virtual Reality Modeling Language (VRML), and Internet newsgroups.

1996: Internet Explorer 3.0

In August 1996, Microsoft released its completely rebuilt Internet Explorer technology, which included features that were revolutionary for the time. Designed for Windows 95, Internet Explorer 3.0 technology offered useful components that immediately appealed to users, including Internet Mail and News 1.0 and Windows Address Book. Later, Microsoft NetMeeting® and Windows Media Player were added. Now the Internet Explorer browser could display GIF and JPG files, play MIDI sound files, and play streaming audio files without the assistance of helper applications.

For Web developers, Internet Explorer 3.0 technology delivered a flexible programming model with a choice of scripting languages. Moreover, Internet Explorer 3.0 was designed to allow Web developers to extend it easily at a time when Internet standards were quickly evolving.

1997: Internet Explorer 4.0

Designed for Windows 95, Windows 98, and Windows NT®, Internet Explorer 4.0 technology was a significant move forward. For Web developers, the addition of Dynamic HTML (DHTML) heralded the next step in Web design. DHTML gave Web developers more control over content and style and created opportunities that previously had been possible only with software applications.

Suddenly Web pages became much more interactive—users could expand menus with a click or drag images and objects around. The Web started to look more like the applications and games that people were accustomed to and less like a static series of pages.

With Internet Explorer 4.0, Microsoft Outlook® Express 4.0 was also installed for the first time as an upgrade to Internet Mail and News. This built-in component improved the way users sent, received, and organized their e-mail and address book.

1998: Internet Explorer 5.0

With the September 1998 release of Internet Explorer 5.0 technology, developers gained the ability to design richer Web applications. DHTML capabilities were expanded, giving Web developers more flexibility and power to create interactive Web sites.

Now personalization became a key focus as Web applications based on DHTML emerged. Users encountered rich applications on the Web—for example, an expense report could automatically configure itself based on a user's personalized settings. With expanded programming capabilities such as these, Internet Explorer 5.0 technologies helped user in a new era of e-commerce.

2001: Internet Explorer 6

Internet Explorer 6 technology was released with Windows XP in 2001 as a more private, reliable, and flexible technology than previous versions. Because privacy and security had become customer priorities, Microsoft implemented tools that support Platform for Privacy Preferences (P3P), a technology under development by the World Wide Web Consortium (W3C).

From the home user simply browsing content on the Web, to the IT administrator deploying and maintaining a rich set of Windows Internet technologies, to the Web developer creating rich Web content, Internet Explorer 6 technologies provide the freedom to experience the best of the Internet.

  •  Give synonyms to the following words from the text:

Beginning, main, answer, additional peripheral, available, huge, characteristic, at once, to attract smb., help, to develop, to announce, before, to be used to, to make better, to achieve, to appear, to face, former, to supply.

  •  Sum up the information given about each Internet Explorer and express it in one sentence.

  •  Using the following expressions write the annotation to the text:

The text deals with ….

As the title implies the text describes …

It is specially noted …

A mention should be made …

It is spoken in detail …

The text gives valuable information about …

The text is of great help to …

It gives a detailed analyses of …

It draws reader’s attention to …

… is (are) proposed.

… is (are)examined.

… is (are)discussed.

LISTENING SKILLS

  •  Listen to the interview with David Collins,

                                    the president of Videotex Link. He is explaining videotex system to a journalist. Complete the journalist’s notes.

Videotex: interactive system of information.

Allows anybody with a telephone and appropriate equipment to access a wide range of services.

  •  Need a ……… to be connected to a videotex network
    •  To install a modem one cable of modem is connected to ……

and the other to …………………………………………………….

  •  Public videotex system in Europe:

New Prestel in the UK

Teletel in France

Ibertex in ……………………………………………………………

Videotel in ………………………………………………………….

  •  Specialized services offered by the French Minitel system: ………

-       Information services provided by videotex: current affairs, entertainment, …………………………………………………………

 

  •  Listen to the interview with Tom Bryant, a writer with a computer magazine. Are the following sentences true or false?

  1.  A pen-based interface uses an electronic stylus as an input device.
  2.  Pen computers do not require specialized operating systems to recognize pen gestures and characters.
  3.  Pen computers come with operating systems that can be trained to recognize handwriting.
  4.  Some pen computers are more powerful than desktop PCs.
  5.  A Personal Digital Assistant is a hand-held pen computer designed to organize and communicate personal information.
  6.  You cannot transmit data from pen computers to desktop PCs and peripherals.
  7.  Business people will make up a large section of the pen computer market.

  •  Read this extract from the interview and fill in the missing words. The first letters of each missing word is given.

Interviewer: Can you explain how a (1) p……… computer work?

Tom Bryant: Sure. A pen computer usually (2) r….. on rechargeable

                    alkaline batteries. You hold the computer with one hand and

                    with the other you use an electronic (3) s……. to write, draw

                    and make selections on a flat LCD (4) s………….

Interviewer: That means it doesn’t have a keyboard.

Tom Bryant: That’s right. You write (5) i…….. with the stylus like a pen.

Interviewer: And how does the computer (6) r…….. what you write?

Tom Bryant: It reads the (7) p……… of the pen and sends signals to the

                     screen. The computer then translates the movements of the

                     pen into characters or performs the functions like ‘delete’.

                     The operating system recognizes specific gestures.

DISCUSSION

                                                      Working in pairs make up dialogues

                                   discussing the following problems.

  1.  You friend has just bought a computer and he is in doubt whether to use the Internet or not. Describe him pros and cons of this global net.
  2.  One of you is going to send a letter to your friend using the post office. The task of the other student to advise him to use the e-mail.

3. Can we balance the use of technology and real-life conversation? How?

SUPPLEMENTARY READING

                                                          

                            THE LANGUAGE OF E-MAIL

                                            

                           E- mail is the simplest and most immediate

                      function of the Internet for many people. Run trough a

                      list of questions that new e-mail users ask most and

                      some snappy answers to them.

What is electronic mail?  E-mail, as it’s normally shortened to, is just a message that is composed, sent or read electronically (hence the name). With regular mail you write your message (letter etc) and drop it off at the post office. The postal service then delivers the message and the recipient reads it. E-mail operates basically the same-way except that everything happens electronically. You compose your message using       e-mail software, send it over the lines that connect the Internet’s networks and the recipient uses an e-mail program to read the message.

How does e-mail know how to get where it’s going? Everybody who’s connected to the Internet is assigned a unique e-mail address. In a way, this address is very like the address of your house or apartment because it tells everyone else your exact location on the Net. So anyone who wants to send you an e-mail message just tells the e-mail program the appropriate address and runs the Send command. The Internet takes over from there and makes sure the missive arrives safely.

What’s this netiquette stuff I keep hearing about? The Net is a huge, unwieldy mass with no ‘powers-that-be’ that can dictate content or standards. This is, for the most part, a good thing because it means there’s no censorship and no one can wield authority arbitrarily. To prevent this organized chaos from descending into mere anarchy, however, a set of guidelines has been put together over the years. These  guidelines are known collectively as netiquette (network etiquette) and they offer suggestions on the correct way to interact with the Internet denizens. To give you the taste of  netiquette, here are some highlights to consider.

  •  Keep your message brief and to the point and make sure you clear up any spelling slips or grammatical gaffes before shopping it out.
  •  Make sure the Subject lines of your message are detailed enough so they explain what your message is all about.
  •  Don’t SHOUT by writing your missive entirely in uppercase letters.
  •  Don’t bother other people by sending them test message. If you must test a program, send a message to yourself.

What’s a flame? The vast majority of e-mail correspondence is civil and courteous, but with millions of participants all over the world, it’s inevitable that some folks will rub each other the wrong way. When this happens, the combatants may exchange emotionally charge, caustic, often obscene messages called flames. When enough of these messages exchange hands, an out-and-out flame war develops. These usually burn themselves out after a while, and then the participants can get back to more interesting things.

Is e-mail secure? In a word no. The Net’s open architecture allows programmers to write interesting and useful new Internet services, but it also allows unscrupulous snoops to lurk where they don’t belong. In particular, the e-mail has two problems: it’s not that hard for someone else to read your e-mail, and it’s fairly easy to forge an e-mail address. If security is a must for you, then you’ll want to create an industrial strength password for your home directory, use encryption for your most sensitive messages, and use an anonymous remailer when you want to send something incognito.

FINAL TEST

  •  Find and match the pairs of expressions from the

                         left and right columns that have the same meaning (Найдите и  соотнесите пары выражений из левой и правой колонки, обладающие одинаковым значением)

  1.  modem                                    A. telephone line
  2.  baud                                        B. network
  3.  telecommunication link          C. workstation
  4.  fibre-optic cable                      D. bits per second
  5.  terminal                                   E. modulator/demodulator
  6.  web                                          F. thin strands of glass

  •  Choose the sentences which are true to the information of the introductory text (Выберете предложения, соответствующие информации вводного текста)

7.  A. Terminals of data communications system share the same software and hardware.

  1.  Data communications over long distances can’t make use of microwave radio links.
  2.  A graphics terminal is usually used for Computer-Aided Design.
  3.  Telephone lines carry digital signals.
  4.  Dish aerials are usually situated at the top of high towers.
  5.  Any terminal has  one input device and output device.

  •  The main idea of the text « Internet Explorer History » can be expressed as: (Главная идея текста  может быть выражена как:)

8. A. The development of Internet Explorers has a long history.

  1.  The development of Internet Explorers  made Internet more accessible for many people.
  2.  The development of Internet Explorers  makes Internet more accessible and their new versions opens more and more abilities for Internet users.

  •  Give the right Russian equivalent to the following English word combinations (Дайте верный русский эквивалент английским словосочетаниям)

9. dedicated line                               A. автоматическая линия

                                                        В. специализированная линия

                                                        С. разветвленная сеть

10. loop network                              А. однокабельная сеть

                                                        В.  локальная сеть 

                                                        С.  разветвленная сеть

11.  data communications system    А. система базы данных

                                                        В. система передачи данных

                                                             С. система хранения данных

  •  Give the right English equivalent to the following Russian word combinations (Дайте верный английский эквивалент русским словосочетаниям)

12. акустический коммутатор

13. однокабельная сеть

14. графический терминал

15. световое перо

16. дистанционный доступ

  •  Complete the sentences with the proper word (Закончите предложения подходящим по смыслу словом)

17. LAN stands for  …….

18.  …… converts analogue signals into digital signals and vice versa.

19. Computers make use of …… signals.

20. Windows 95 with Internet Explorer 1.0 debuted in …….

21. Internet Explorer 6 technology was released in 2001 with …..

  •  Find the equivalents in two languages (Найдите эквиваленты в двух языках)

22. plug                            А. отдельно

23. amplify                        В. прядь  

24.  strand                          С. волна    

25. apart                             D. усиливать    

                                          E. вставлять штепсель                

  •  Choose the right variant (Выберите правильный вариант)

26. …….. gives computer user the opportunity to send a message to somebody without leaving home.

    A. Aerial                                 B. E-mail

C. Modem                              D. Display

27. A special kind of modem with rubber cups is known as …….                                     

    A. Acoustic coupler                     B. Demodulator

    C. Modulator                                D. Fibre-optic cable

28. A network contained in a relatively small area is known as …..

    A. WAN                                      B. Loop network

    C. LAN                                        D. Single cable network


 

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  В процессе игры у детей вырабатывается привычка сосредоточиться мыслить самостоятельно развивает внимание стремление к знаниям. По спектру целевой ориентации игры подразделяются: дидактические: расширение кругозора познавательная деятельность; применение ЗУН в практической деятельности; формирование определенных умений и навыков необходимых в практической деятельности; развитие общеучебных умений и навыков; развитие трудовых навыков. В нее включаются последовательно игры и упражнения формирующие умение выделять основные характерные...