2. Definition
● When two or more computers are
interconnected with each other but
located at different geographical location
● To share resources and data .
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3. Basic Elements of Communication
System
● Message – information such as data like text, picture, sound, video
etc are to be communicated
● Sender - Creates and sends a message
● Medium – Carries the message
● Receiver – Receives the message
● Protocol – set of rules that govern data communication
SENDE Receiver
R
Mediu
m
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4. Data Transmission Mode
● There are three modes of data
transmission
○ Simplex
○ Half Duplex
○ Full Duplex
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6. Simplex
● Transmission of data in only one direction
is known as simplex transmission mode
● Devices used in such communication
system are either read only or send only.
For example
● Keyboard
● Printer
● Pager
● Wakie-Talkie
8. Half Duplex
● A communication system in which we can
transmit data in both directions but in only
one direction at a time.
● It alternates sender and receiver.
● Requires two channels
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