Overview of this chapter

SectionSub-sectionPage
2.1 Catergories of data transmission2.1.1 Classification by direction2
2.1.2 Classification by serial / parallel
2.1.3 Classification by synchronization
2.2 Error detection2.2.1 Parity check3
2.2.2 Check sum / digit
2.2.3 ARQ
2.2.4 Echo check
2.3 USB4

Maintenance History

UpdatedAuthorRemarks
02/08/2020 (Current)JohnRe-organized the structure of notes.
10/30/2019JohnMoved from old server

Next page: 2.1 Categories of data transmission


2.1 Categories of Data transmission

2.1.1 Classification by direction

  • Simplex: One direction            (Radio stations)
  • Half-duplex: Two directions, not simultaneously (Walkie-talkie)
  • Full-duplex: Two directions, simultaneously  (Phone line)

2.1.2 Classification by transmission

  • Serial: Single line, one bit at a time.
   Computer   
  A     B
A0------------>B0
  • Parallel: Multiple bits transfer simultaneously on separate lines.
   Computer   
  A     B
A0------------>B0
A1------------>B1
A2------------>B2
A3------------>B3
A4------------>B4
A5------------>B5
A6------------>B6
A7------------>B7
#Alan-------->Blan#

2.1.3 Classification by synchronization

FeaturesSynchronous data transmissionAsynchronous data transmission
Transmission MethodTiming signals ensure that sender and receiver syncedEach character divided into a data block
They are synced by an Internal clock inside CPUControl bits tells that where data starts and ends
Example[SYNC, SYNC, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1...][START, 1, 1, 1, ... ,0, 1, 1, 0, STOP]
PackingData would keep steaming as long as computers are not out of syncEach character must be packed as shown above
SpeedFasterSlower
ReliabilityUnreliable — data might be muddled over timeReliable — since one bit at a time
Only suitable for short distance (Otherwise computers would be out of sync)

Next page: 2.2 Error detection



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