The document discusses various topics related to data communication and computer networks. It defines data communication, describes the characteristics and components of data communication such as delivery, accuracy, timeliness, jitter, message, sender, receiver, transmission media, and protocols. It also discusses data representation, data flow modes, compatibility issues, definitions of a network, reasons for networks, distributed processing, factors to consider when setting up a network like performance, reliability and security, types of network connections like point-to-point and multi-point, and network topologies including mesh, star, bus and ring.

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Topic 1: Data Communication

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Data Communication:
What is Data Communication?
Data communication is the exchange
of data between two devices via
some form of transmission medium
such as a wire cable

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Data Communication:
What are the characteristics of data communication?
Delivery
Refers to the system being able to deliver data to the correct destination.
Data must be received by the intended device or user and only by that
device or user.
Accuracy
The system must deliver the data accurately. Data that have been
altered in transmission and left uncorrected are unusable.
Timeliness
The system must deliver data in a timely manner.
Jitter
Refers to the variation in the packet arrival time. It is the uneven delay in
the delivery of audio or video packets.

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Data Communication:
What are the components of data communication?
Message
The message is the information that is communicated. E.g. text, numbers,
pictures, audio, and video.
Sender
the device that sends the data message. E.g. Phone, computer
Receiver
the device that receives the data message. E.g. Phone, computer , radio,
television
Transmission Media
It is the physical path by which a message travels from sender to receiver.
Protocol
A set of rules that govern data communications. It represents an
agreement between the communicating devices

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Data Communication:
What are the components of data
communication?
.

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Data Representation:
What is data representation?
A way of presenting data into something the computer
can understand.
How can data be represented?
Text
is represented in bit pattern (a sequence of 1’s and
0’s). The prevalent coding system is called Unicode,
which uses 32 bits to represent a symbol or character
used in any language in the world.
Numbers
are also represented in bit pattern

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Image
Also represented by bit patterns. An image is
composed of a matrix of pixels
Audio
refers to the recording or broadcasting of sound
or music. It is continues, not discrete.
Video
refers to the recording or broadcasting of a picture or
movie. It can be a combination of images, each a
discrete entity, arranged to convey the idea of motion.

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Data Flow:
What is data flow?
Its simply the way data flows from one device to
another.
In which ways or modes can data flow?
Simplex
Data flows in one direction only
Half duplex
Data flows in both ways, but not at the same time.
Full Duplex
Data flows in both directions at the same time
(simultaneously)

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Compatibility Issues:
When selecting between broadband and
baseband or half-duplex and full-duplex, you
need to remember that your decision is not
just for an individual computer. Rather, it is a
decision for all devices that will communicate
on your network.

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Networks:
What is a network?
A network is a set of devices (often referred to as nodes)
connected together by communication links. A node can be a
computer, printer, or any other device capable of sending
and/or receiving data generated by other nodes on the
network.
What do we need networks for?
Sharing of resources
Sharing of work
Cost reduction
Availability and rateability
Communication media

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Distributed Processing:
What is distributed processing?
When a task is shared amongst multiple computers instead
of one single computer doing all the work.
How does it work?
There is usually a group of computers linked together with
one of them acting as reception and only directing requests
to intended server specializing in those particular requests.

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Network Criteria:
What needs to be considered when setting up
a network?
Performance
Reliability
Security

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Types of Connections:
How can networks be connected?
Point –to-point
A direct connection between devices in a network
Multi-point
Devices in a network are connected through a single link

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Network topologies:
What is a network topology?
A network topology is the geometric
configuration of devices, nodes, and cable
links on a network

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Network topologies:
Types of network topologies?
Mesh Topology
Star Topology
Bus Topology
Ring Topology