This document discusses key topics in data communication including hardware, protocols, and types of computer networks. It describes how modems and other hardware like network interface cards are used to connect computers and transmit data. Common wired and wireless transmission media are also outlined. The document defines protocols as sets of instructions that control transmission and maintains networks. Examples of protocols like TCP/IP and HTTP are provided. Finally, the main types of computer networks - the Internet, intranets, and extranets - are summarized in terms of their purpose and how they connect different users.

1. By: Azar Abid Salih
MSc of Computer Science
D.P.U / Administrative Technical College
IT Dept. / First Class
Information Technology
Fundamentals
Lecture 6
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2. • Data Communication Hardware
• Protocols
• The Internet
• Intranet
• Extranet
Outlines:
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3. Data Communication Hardware:
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 To control data transmission through
Networks and Internet, the following
is considered:
1. A Modem (Modulate/Demodulate):
Converts digital signals into analog form
(a process known as Modulation) to send over
phone lines. A receiving modem at the other
end converts the analog signals into digital
signal (a process known as Demodulation).

4. Data Communication Hardware:
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2. Integrated Services Digital Network:
ISDN is designed to transmit the digital
signals with more speed but with extra cost. A
modem is not needed here.
3. Asymmetric Digital Subscriber Line (ADSL):
Is a new technology that allows more
data to be sent over the existing copper
telephone lines.

5. Data Communication Hardware:
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4. Network Interface Card (NIC):
It is a circuit that is plug in expansion
slots so the computer can be connected to
others, it transmits data, executes protocols.

6. Data Communication Hardware:
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5. Transmission Media:
Are used to send data over the network.
 Wired Media:
 Twisted Pairs Wire.
 Coaxial Cables.
 Fiber Optics.
 Wireless Media:
 Radio Waves.
 Microwaves.
 Satellite.

7. Set of instructions and procedures
that maintain and control transmission in
networks.
For example:
 Internet Protocol: TCP/IP
 Token Ring Protocol
 HTTP , TCP , UDP
Protocols:
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8. A network of computers and
computer networks around the world
that is linked by means of a
telecommunication network.
 Internet Services:
 Search Engines.
 Electronic Mail.
The Internet:
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9. Is a private network that is
contained within an enterprise.
The main purpose of an intranet is
to share company information and
computing resources among employees.
Intranet:
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10. Is a private network that uses
Internet technology and the public
telecommunication system to securely
share part of a business’s information or
operations with suppliers, vendors,
partners, customers, or other businesses.
Extranet:
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11. The END…
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