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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

Computer Studies

Computer Communication and Networking

table of contents
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)

stage of communication
Stage of communication
  • Encoding
  • Transmission
  • Decoding

Where do each

stage take

place ?

Sending device

Receiving device

encoding
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

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

Signal transmitted

by telephone line

Sending device

Receiving device

decoding
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

computer network
Computer Network

Workstation

Workstation

Printer

Scanner

Workstation

Server

slide10

This is the end of

Concept of Computer Communication

Back to Table of Content

Next Section

sharing of resources
Sharing of resources

Can I use the Laser Printer ? How ?

sharing of resources1
Sharing of resources

Connected

Connected

sharing of resources2
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
communicate with one another1
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
centralized control and better security
Centralized control and Better security

The network supervisor

better security

measures

centralized

control over all

facilities and

resources

centralized control and better security1
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
easier software management
Easier software management

Server

Install

new

software

Use new software

Use new

software

Use new

software

easier software management1
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
flexibility of location
Flexibility of location

Workstation

New Workstation

New Scanner

New Printer

Workstation

Server

flexibility of location1
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
slide23

This is the end of

The Need for Networking

Back to Table of Content

Next Section

slide25

L

A

N

L

L

A

A

N

N

L

A

N

Local Area Network

- Within a room, floor or building

FAST!

slide26

M

A

N

M

A

N

M

A

N

M

A

N

Metropolitan Area Network

- Within a large city

- Optical fibers as media

slide27

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

slide28

This is the end of

Types of Networks

Back to Table of Content

Next Section

network topology

Network topology

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

star architecture

Yes, I can hear you

Transferring

Hello?

Star architecture

Host

Node

star architecture1

????

I can’t work!

Hello?

Star architecture

Host

Node

star architecture2

Yes, I can hear you

Transferring

Hello?

Star architecture

Host

Node

star architecture3
Host fails,

whole network breaks down

Node fails,

network not affected

Configuration is simple

Star architecture
ring architecture

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

ring architecture1

PC1, I love U!

Ring architecture

????

Oh, I can’t transfer

your message!!

ring architecture2
All computers are

Nodes

If any node fails,

whole network break down

Ring architecture
bus architecture
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!

bus architecture1
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!

bus architecture2
All Nodes connected to

BUS

If any node fails,

network not affected

Bus architecture
slide40

This is the end of

Network Topology

Back to Table of Content

Next Section

slide42

Two ways of transmission data:

1. Direct mode transmission

Signals are transmitted to a particular receiver

slide43

Signals are transmitted to all directions

2. Broadcast mode transmission

direct mode transmission

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

slide45

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

slide46

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
slide47

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
slide48

This is the end of

Means of Communication

Back to Table of Content

Next Section

use of world wide web www

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

what is web browser
What is Web Browser ?

Web Browser is a software to:

1. Traverse the links in the Web

2. Communicate with servers

3. Retrieve data

two popular web browsers
Two popular Web Browsers

1. Netscape

2. Internet Explorer

slide55

Type in the address and press enter

  • Address of Web Site is called URL(Uniform Resource Locator)

e.g. http://www.singtao.com

http://www.singtao.com

suggestions of interesting web sites
Suggestions of Interesting Web Sites
  • Newspapers
    • Singtao Daily News

http://www.singtao.com/

    • Apple Daily News

http://apple.daily.com.hk/

slide58
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

slide59
Games
    • Cow boyhttp://www.shinenet.com.tw/fashion/game92/index.html
slide60
Matching Games

http://personal.cityu.edu.hk/~96013494/matching/

slide61
Game

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

slide62
Comics
    • 叮噹網頁

http://home.hkstar.com/~fucp/fujiko/doraemon/dora.htm

slide63

This is the end of

Use of World Wide Web

Back to Table of Content

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