bbit 313 unit 1 introduction definitions and data transmission

8/3/2019 BBIT 313 Unit 1 Introduction Definitions and Data Transmission

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TOPIC 1: INTRODUCTION, DEFINITIONS &DATA TRANSMISSION

SLIDES PREPARED BY: MSAGHA.J.MBOGHOLI


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Data communication: communication of infoby electronic means, usually over somedistance.

Networks allow people to be connectedtogether: advantages of this?

Connectivity and communication, datasharing, hardware sharing, internet access,

internet access sharing, data security andmanagement, entertainment, etc


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Bit rate

Baud

Baud rate


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Parallel transmission data transmitted viaparallel mode on buses with the width of theparallel bus matched to the word size of thecomputer.

In parallel transmission bits are sentsimultaneously on different channels withinthe same cable, or radio path, and

synchronized to a clock


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The parallel transmission bit rate is fasterthan serial transmission bit rate.

However cost of wires needs to be considered

Also as distance becomes longersynchronization timing between multiplechannels becomes more sensitive

Timing is provided by a constant clocking

signal and therefore considered synchronous


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How can we illustrate parallel transmissionusing a diagram?

Serial transmission: Bits are sent sequentially on the same

channel.

Reduced cost but also slower transmission

speed.


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Serial transmission can be either synchronousor asynchronous.

Synchronous

Asynchronous How can we illustrate this in a diagram?


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Applications? Serial: between two computers or from

computer to an external device located somedistance away, e.g., computer to modem.How does this happen?

Parallel: either takes place within a computersystem (on the bus) or to an external device

located a short distance away, e.g., computerto printer


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UART (Universal Asynchronous ReceiverTransmitter): acts as the interface betweenthe parallel transmission of the computer busand the serial transmission of the serial port.

Performance capability depends on amount ofon-chip memory possessed.


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Asynchronous: character by charactertransmission

1 character = a series of bits

Receiver needs to be synchronized with thesender.

Each character will possess a start and stopbit.

Can we show this in a diagram?


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Synchronous transmission: block by blocktransmission.

Receiver is synchronized with sender PRIOR totransmission of continuous stream.

Receiver tunes-in to group of bits beingtransmitted by sender.

Normally makes use of a SYNchronizing

character.


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Differences: Asynchronous: char by char; each char has

start and stop bit; useful in instances ofintermittent transmission of small amounts ofdata; slow therefore not suitable fortransmission of large amounts of data;overhead of extra bits added to each char

Synchronous: block by block requires SYNchar; each block has stop bits; inefficient forintermittent short messages (why?)


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Acknowledgement: Salim Athman

bbit 313 unit 1 introduction definitions and data transmission

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