Computer Architecture29x

frogvillesafeElectronics - Devices

Nov 27, 2013 (3 years and 7 months ago)

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Computer Architecture

Lecture 29

Fasih

ur

Rehman

Last Class


Memories


Virtual memory


Address Translation


Memory Management

Today’s Agenda


Computer Communication

Analog Vs. Digital


Data Communication


Transmission of data (voice, video or text) via
electrical, optical or wireless link between
computers or network processors is referred
to as Data Communication


In computer communication, the data is generally
digital.


Mostly, the data that is required to be communicated
is in analog form.


So an analog to digital converter ADC will be required
to convert the analog data into digital data.


The link can be


Free space


Wires (twisted pair, coaxial cable, parallel conductors)


Optical fiber

Why Digital


Easy to mix signals and data using digital
techniques


Less
noise prone


Good
processing techniques are available for
digital


signals, such as


Data
compression (or source
coding)


Error
Correction (or channel coding)


Equalization


Security

Components of a Communication System


Source (Transmitter)


Medium (Communication Line)


Sink (Receiver)


Communication networks


Communication rules (protocols
)


Both source and sink act as node


History


Telegraph


Telephone


Computer


Transistor


Integrated Circuits (LSI, VLSI)


Satellites

Transmission Direction


Simplex


One way communication e.g. TV transmission


Half Duplex


Two way communication but not simultaneously


e.g.
walkie

talkie


Full Duplex


Simultaneous two way communication


telephone


Codes


Human Codes


Morse Code


Dots and Dashes


Machine Codes


Binary codes


use binary states


use same number of bits


so transmitted in same time


perfectly formed


alphanumeric


Common Codes


Baudot

code


ASCII


EBCDIC


Unicode

Some Commonly used Terms


Throughput


The number bits transferred per second.


Also called bandwidth


Latency


The that is elapsed between initiation of
transmission and earliest possible reception of a
give piece of information.


Also called delay


Network Topology


The way hosts are connected to the network


Star, ring topologies etc.


Main goal of topology is to have minimum latency with
high throughput


Some commonly used topologies are described as

Mesh


All nodes are connected to each other.


Bus Topology


All nodes are connected to a common bus

Star Topology


All nodes are connected to common hub.

Ring Topology


All computers are connected in a way that
they form a loop.

Hybrid Topology


Mix of the above topologies

Protocols


Set of rules to be followed in order to
communicate among the network nodes

Summary


Data Communication


Signals


Analog and Digital