Computer Communication

Computer networking enables the sharing of hardware, data and other resources.  It also provides a base for communication among users.

Types of network

Network Devices

 Types of network: 

  1. The micro/mainframe link 

A central computer that is responsible to deal with all applications is connected to a number of terminals.  

  2 . Local area network (LAN)

A LAN links independent computers and other peripheral devices over short distances, for example, in a school. The hardware is connected by cable. In a typical LAN, peripheral equipment, software and database resources may be shared among the computers connected.

  3. Wide area network (WAN)

A wide area network links computer systems over long distances, such as over continents. For example, a company with three branches in different countries, it may need WAN in order to communicate among different branches.

 Network devices 

1. Modem

When two computers communicate to each other over a telephone line, modem is needed. A modem is used to converted digital signals to analogue signals. This is called modulation. If the analogue signals convert back to digital signals, this is called demodulation.

	digital signal		analogue signal		digital signal
		Modem		Modem

2. Twisted-pair wire

It is typically used for telephone lines. It is cheap but has the lowest capacity. Modem is needed for signal conversion.

3. Coaxial cable

It is more expensive than twisted-pair wire but has a greater capacity to transmit data. It is also more reliable as it is better insulated and better protected. It is commonly used for LAN application.

4. Optical fiber

It can carry many signals simultaneously, both voice and data signals can be carried on the same line. Its advantages make it become more and more popular communication devices now.

Low transmission loss, large transmission capacity, small size, and light weight. It is easy to install, and suitable for large capacity telecommunication system.

Of courses, software is needed to make communication between computers possible. Also, software is essential to enable computers with different configurations to send messages to each other. The software required is called communication software. 

There may be thousands of such communication software. A common one used in LAN is Novell. 

We now always heard of Internet explore (IE), Netscape communicator, these are common browser that we use today. 

 For Communication 

The usual methods for communication are: electronic mail (e-mail), chat rooms, icq, etc. For now, there are even more devices such as web cam, or net meeting ( which use microphone and web cam to 'talk' to others), etc.

Have you surf the net today?

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