VAGUE DEFINITIONS We will clarify

Data Communication System
For Data Communication to occur, the communicating devices must be a part of a
communication system made up of some specific kind of hardware and software
This type of a system is known as a

“DATA COMMUNICATION SYSTEM”

Effectiveness of Data Comm. System
Effectiveness depends upon three fundamental characteristics:

• Delivery
• Accuracy
• Timeliness (Better NEVER than LATE)

Example of the POSTAL MAIL

TODAY’S EVERGHANGING & BUSY WORLD

• Today’s fast world demands better, secure and most of all FAST ways of communication
• Gone are the days when you had to wait a couple of weeks to get a letter from USA
• Why wait ONE week when you can get the information you require in just a split of a second, using what we know by the name of “DATA COMMUNICATION”.

HOW TO ACHIEVE THIS?

• How to achieve this ACCURACY, SECURITY and SPEED for the transfer of this information?
• What HARDWARE, and the SOFTWARE is needed ?
• And, what should be the MEANS of sending this info?

ARE SOME OF TOPIC WE WILL BE EXPLORING DURING THE COURSE OF
OUR STUDY

DATA COMMUNICATION

• When we communicate , we share information
• Information can be LOCAL or REMOTE
• Between Individuals LOCAL communication occurs face to face
• REMOTE communication occurs over a long distance
• When we refer to COMPUTER SYSTEMS, Data is represented in the form of Binary Units (Bits) in the form of Zeros (0’s) and One’s (1’s)
• Also the entities can most of the times be considered to be COMPUTERS

Data Communication Definition (Modified)

Therefore , our earlier definition can easily be modified to:
“Data Communication is the exchange of data (in the form of 0’s and 1’s)
between two devices (computers) via some form of the transmission medium.”

LOCAL and REMOTE Data Communication

LOCAL
Data communication is considered to be local if the communicating devices
are present in the same building or a similarly restricted geographical area
REMOTE
Data Communication is considered remote, if the devices are farther apart.

INTRODUCTION TO DATA COMMUNICATION

DEFINITION OF DATA COMMUNICATION
“Data Communication is the exchange of Information from one entity to the other
using a Transmission Medium”.

DEFINITION OF DATA COMMUNICATION (Cont’d)
As you can clearly notice, the definition of Data Communication although Simple
leaves many questions unanswered:

• Exchange??????
• Information?????
• Entities???????
• Transmission????
• Medium????

We will try to answer all these Questions in this Course

History of Data Communication
Data communications history represents a blend of histories, including:

• The history of the telecommunications industry
• The history of data communications, and
• The history of the Internet
• Telegraph 1837 Samuel Morse

Telegraph 1837 Samuel Morse
Modern telecommunication industry began in 1837 with the invention of
the telegraph by Samuel Morse
This led to building a telecommunications infrastructure of poles and
wires as well as to the development of communication hardware and
protocols

Telephone 1876 Alexander Graham Bell
Invention of telephone by Alexander Graham Bell in 1876 and the
development of wireless communication technology by Guglielmo
Marconi in the 1890s set the stage for today’s communication industry

By 1950’s
By 1950s, telephone and telegraph companies had developed a network of
communication facilities throughout the industrialized world

1970’S
Although development of databases, languages, operating systems, and
hardware was strong from 1950s to 1970s, large-scale data communication
systems did not emerge until the 1970s.

This was stimulated by 3 major developments:

• Large-scale integration of circuits reduced cost and size of terminals and communication equipment
• New software systems that facilitated the development of data communication networks
• Competition among providers of transmission facilities reduced the cost of data circuits