Computer Studies

1
Computer Studies

• Computer communication and networking

2
Group
Author

• Lam Ka Po, Angela 98104740
• Ma Wai Kin, Winky 98104410
• Lam Chi Man, Andy 98104660
• Each of the team member is responsible for 2 of
  the 6 sections

3
Introduction
Target audience S5 science students with
average ability Attitude Active, eager for
learning, interest in Internet Background
Knowledge Simple concepts of data communication

• For lecturing purpose
• Questions are incorporated in the presentation
• Use of large amount of figures and animations to
  illustrate abstract concepts of networking
• Last section serves as a practical activity
  involving students participation
• Small test will be given on papers at the end of
  chapter

4
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)

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5
Concept of computer communication
6
Concept of computer communication
Data
Telephone Line
7
Stage of communication
Where each stage take place ?

• Encoding
• Transmission
• Decoding

Sending device
Receiving device
8
Encoding

• Information (e.g. data, text, voice or video)
  from the sending device is converted into signals
  which the communication medium can carry

9
Transmission

• The signals are transmitted through the medium to
  the receiving device

Signal transmitted by telephone line
Sending device
Receiving device
10
Decoding

• The signals are converted back into the
  information in its original form in the receiving
  device

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Computer Network
Server
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This is the end of Concept of Computer
Communication
Back to Table of Content
Next Section
13
The need for networking
14
Sharing of resources
15
Sharing of resources
Connected
Connected
16
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

17
Communicate with one another
IBM PS/2
Mac
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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

19
Centralized control and Better security
The network supervisor
better security measures
centralized control over all facilities and
resources
20
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

21
Easier software management
Server
Install new software
Use new software
Use new software
Use new software
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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

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Flexibility of location
Server
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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

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This is the end of The Need for Networking
Back to Table of Content
Next Section
26
Types of networks
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Local Area Network
- Within a room, floor or building
FAST!
28
Metropolitan Area Network
- Within a large city - Optical fibers as media
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Wide Area Network
- link small networks in different geographic area
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This is the end of Types of Networks
Back to Table of Content
Next Section
31
Network topology

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

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Star architecture
Host
Node
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Star architecture
Host
Node
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Star architecture
Host
Node
35
Star architecture

• Host fails,
• whole network breaks down
• Node fails,
• network not affected
• Configuration is simple

36
Ring architecture
I know u love me, but I hate u !
Oh, not for me, I will pass the message
All Computer are nodes
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Ring architecture
????
Oh, I cant transfer your message!!
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Ring architecture

• All computers are
• Nodes
• If any node fails,
• whole network break down

39
Bus architecture
Not my message, I wont pick up
What! The deadline has changed??
Not my message, I wont pick up
Its my message, I will pick it up
Node
BUS
Not my message, I wont pick up
You have to hand in your homework today!
40
Bus architecture
Not my message, I wont pick up
What! The deadline has changed??
Its my message, I will pick it up
Node
What will happen?
BUS
Not my message, I wont pick up
You have to hand in your homework today!
41
Bus architecture

• All Nodes connected to
• BUS
• If any node fails,
• network not affected

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This is the end of Network Topology
Back to Table of Content
Next Section
43
Means of communication
44
Two ways of transmission data

• 1. Direct mode transmission

Signals are transmitted to a particular receiver
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2. Broadcast mode transmission
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Direct mode transmission

• 1. Twisted wires

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2. Coaxial cable
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• 3. Optical fibre

• Very expensive transmission medium
• Not subject to electrical disturbance
• Suited for long distances communication in high
  data rate

- Light passes along the coated fine cylindrical
glass tubing by reflection
49
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
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This is the end of Means of Communication
Back to Table of Content
Next Section
51
Use of world wide web(WWW)
The Internet
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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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Two popular Web Browsers
1. Netscape
2. Internet Explorer
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Use of Web Browser
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(No Transcript)
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• You can see some shortcut key on the browser like
  this

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• Address of Web Site is called URL(Uniform
  Resource Locator)
• e.g. http//www.singtao.com

http//www.singtao.com
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• After that, you can browse the home page that you
  wanted.

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Suggestions of Interesting Web Sites

• Newspapers
• Singtao Daily News
• http//www.singtao.com/
• Apple Daily News
• http//apple.daily.com.hk/

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• 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

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• Games
• Cow boy http//www.shinenet.com.tw/fashion/game92/
  index.html

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• Matching Games
• http//personal.cityu.edu.hk/96013494/matching/

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• Game
• http//personal.cityu.edu.hk/96013494/fool/fool.
  htm

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• Comics
• ????
• http//home.hkstar.com/fucp/fujiko/doraemon/dora
  .htm

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