Wednesday, April 11, 2012

Chapter 2 *continues....

There are 3 types of transmissions timing :

  • Synchronous transmission 
  • Asynchronous transmission 
  • Isochronous transmission 
Synchronous transmission
Data organised into blocks or groups and transferred at regular specified interval
Asynchronous transmission
the process where transmitted data is encoded with start and stop bits, specifying the beginning and
end of each character.
• Data sent without being synchronized 
Isochronous transmission
data is sent at the same time as other related data to support certain types of real time applications e.g streaming voice, video and music

There are 2 types of direction for data transmission:
  • simplex
  • duplex 
    • half duplex
    • full duplex
simplex --> it is one way communications only. Data travels in single direction 
 i.e door bell
• Relatively uncommon in computer
duplex --> half duplex: Data can travel in either direction but only in one direction at a time.
• i.e USB devices 
             --> full duplex: Data can moves in both directions at the same time, such as with a telephones.     Ideal for hardware devices that need to pass large amount of data between each other.
• Many networks and most internet connections are full duplex

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