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Computer Studies

Computer Studies. Computer Communication and Networking. 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). . . . . . Concept of computer communication.

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Computer Studies

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  1. Computer Studies Computer Communication and Networking

  2. Table of contents  Concept of computer communication The need for networking Types of networks Network topology Means of communication Use of world wide web (W W W)     

  3. Concept of computer communication

  4. Concept of computer communication Data Telephone Line

  5. Stage of communication • Encoding • Transmission • Decoding Where do each stage take place ? Sending device Receiving device

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

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

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

  9. Computer Network Workstation Workstation Printer Scanner Workstation Server

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

  11. The need for networking

  12. Sharing of resources Can I use the Laser Printer ? How ?

  13. Sharing of resources Connected Connected

  14. Sharing of resources • Sharing : data, programs and hardware • Data and software can be centrally storedin 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

  15. Communicate with one another IBM PS/2 Mac

  16. 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

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

  18. 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

  19. Easier software management Server Install new software Use new software Use new software Use new software

  20. Easier software management • When a new applications is developed and installed in the server, workstation canimmediately 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

  21. Flexibility of location Workstation New Workstation New Scanner New Printer Workstation Server

  22. 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

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

  24. Types of networks

  25. L A N L L A A N N L A N Local Area Network - Within a room, floor or building FAST!

  26. M A N M A N M A N M A N Metropolitan Area Network - Within a large city - Optical fibers as media

  27. W A N W A N W A N W A N I Love U ! I Love U too ! LAN LAN LAN Wide Area Network - link small networks in different geographic area

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

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

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

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

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

  33. Host fails, whole network breaks down Node fails, network not affected Configuration is simple Star architecture

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

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

  36. All computers are Nodes If any node fails, whole network break down Ring architecture

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

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

  39. All Nodes connected to BUS If any node fails, network not affected Bus architecture

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

  41. Means of communication

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

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

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

  45. 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 2. Coaxial cable

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

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

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

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

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

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