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Computer Studies Computer Communication and Networking.

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Presentation on theme: "Computer Studies Computer Communication and Networking."— Presentation transcript:

1

2 Computer Studies Computer Communication and Networking

3 Table of contents C oncept of computer communication T he need for networking T ypes of networks N etwork topology M eans of communication U se of world wide web (W W W)      

4 Concept of computer communication

5 Telephone Line

6 Stage of communication Encoding Transmission Decoding Where do each stage take place ? Sending deviceReceiving device

7 Encoding Information (e.g. data, text, voice or video) from the sending device is converted into signals which the communication medium can carry Receiving device receive analog signal Sending device send digital signal 010110

8 Transmission The signals are transmitted through the medium to the receiving device Sending device Receiving device Signal transmitted by telephone line

9 Decoding The signals are converted back into the information in its original form in the receiving device Sending device send analog signal Receiving device receive digital signal 010110

10 Computer Network Server Scanner PrinterWorkstationWorkstation Workstation

11 This is the end of Concept of Computer Communication Back to Table of Content Next Section

12 The need for networking

13 Sharing of resources Can I use the Laser Printer ? How ?

14 Sharing of resources Connected

15 Sharing of resources Sharing : data, programs and hardware Data and software can be centrally stored in a computer acting as the file server and accessed by any computer in the network An expensive laser printer can be connected to a computer which serves as a print server and processing printing jobs from other computers

16 Communicate with one another Mac IBM PS/2

17 Communicate with one another Different types of computers store data files using different internal representation methods A network operation system can automatically convert the files into the required representations before they are transferred

18 Centralized control and Better security The network supervisor centralized control over all facilities and resources better security measures

19 Centralized control and Better security The network supervisor can have a centralized control over the use of all facilities and resources including all data, programs, disk spaces and other hardware better security measures can be applied

20 Easier software management Install new software Use new software software Use new software Server

21 Easier software management When a new applications is developed and installed in the server, workstation can immediately use it from any computer upgrading or changing software is simpler because it is now stored in the single file server but not distributed among different computers

22 Flexibility of location Server New Scanner New Printer New Workstation Workstation Workstation

23 Flexibility of location Any computer on the network can be used to access the centralized database or the software and data in the file server it is fairly easy to add a workstation anywhere, relocate a computer to another site, to add a new printer or any other resources

24 This is the end of The Need for Networking Back to Table of Content Next Section

25 Types of networks

26 Local Area Network NALNALNALNAL - Within a room, floor or building FAST!

27 Metropolitan Area Network NAMNAMNAMNAM - Within a large city - Optical fibers as media

28 LAN LAN LAN I Love U !I Love U too ! Wide Area Network NAWNAWNAWNAW - link small networks in different geographic area

29 This is the end of Types of Networks Back to Table of Content Next Section

30 Network topology It refers to the way by which the network hardware (called nodes) are arranged and the means if data flow.

31 Star architecture Host Node Hello? Transferring Yes, I can hear you

32 Star architecture Host Node Hello? I can’t work!????

33 Star architecture Host Node Hello? Transferring Yes, I can hear you

34 Star architecture Host fails, – whole network breaks down Node fails, –network not affected Configuration is simple

35 Ring architecture All Computer are nodes PC1, I love U! Oh, not for me, I will pass the message I know u love me, but I hate u !

36 Ring architecture PC1, I love U! ???? Oh, I can’t transfer your message!!

37 Ring architecture All computers areAll computers are –Nodes If any node fails,If any node fails, –whole network break down

38 Bus architecture BUS Node You have to hand in your homework today! Not my message, I won’t pick up Not my message, I won’t pick up Not my message, I won’t pick up What! The deadline has changed?? It’s my message, I will pick it up

39 Bus architecture BUS Node You have to hand in your homework today! Not my message, I won’t pick up Not my message, I won’t pick up What! The deadline has changed?? It’s my message, I will pick it up What will happen?

40 Bus architecture All Nodes connected toAll Nodes connected to –BUS If any node fails,If any node fails, –network not affected

41 This is the end of Network Topology Back to Table of Content Next Section

42 Means of communication

43 1.Direct mode transmission Signals are transmitted to a particular receiver Two ways of transmission data:

44 2. Broadcast mode transmission Signals are transmitted to all directions

45 Direct mode transmission 1.Twisted pair wires Cheapest transmission medium Susceptible to local electrical noises Usually used for short distance connections such as telephone line

46 2. Coaxial cable Fairly cheap transmission medium An insulating material protect the copper wire Used for connecting a TV set to public antenna More reliable as it is better insulated

47 3. Optical fibre - Light passes along the coated fine cylindrical glass tubing by reflection Very expensive transmission medium Not subject to electrical disturbance Suited for long distances communication in high data rate

48 Broadcast mode transmission Ground station receive the data and beam to the satellite by microwave Satellite will re- transmit data to another ground station Satellite transmission

49 This is the end of Means of Communication Back to Table of Content Next Section

50 Use of world wide web(WWW) The Internet A global network link many networks Can communicate with other people or access information worldwide Use Web Browser to browse through Internet

51 What is Web Browser ? Web Browser is a software to: 1.Traverse the links in the Web 2.Communicate with servers 3.Retrieve data

52 Two popular Web Browsers 1. Netscape 2. Internet Explorer

53 Use of Web Browser

54

55 You can see some shortcut key on the browser like this

56 Address of Web Site is called URL(Uniform Resource Locator) e.g. http://www.singtao.com http://www.singtao.com Type in the address and press enter

57 After that, you can browse the home page that you wanted.

58 Suggestions of Interesting Web Sites Newspapers –Singtao Daily News http://www.singtao.com/ –Apple Daily News http://apple.daily.com.hk/

59 Christmas Card Web Site http://www.comp.hkbu.edu.hk/~c6000171/xmas http://www.casema.net/~pico/kerst/ Meteor shower http://www.glink.net.hk/~sohk/leonid/enter.htm

60 Games –Cow boy http://www.shinenet.com.tw/fashion/game92/index.html http://www.shinenet.com.tw/fashion/game92/index.html

61 –Matching Games http://personal.cityu.edu.hk/~96013494/matching/

62 –Game http://personal.cityu.edu.hk/~96013494/fool/fool.htm

63 Comics – 叮噹網頁 http://home.hkstar.com/~fucp/fujiko/doraemon/dora.htm

64 This is the end of Use of World Wide Web Back to Table of Content


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