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COMMUNICATIONS - DATA TRANSMISSION - TRANSMISSION MODE
Transmission Mode
Two forms of data movement exist: parallel data
transmission and serial data transmission.
- Parallel Transmission: Parallel data
transmission involves the concurrent flow of bits of
data through separate communications lines.
This
pattern resembles the flow of automobile traffic on
a multilane highway. Internal transfer of binary
data in a computer uses a parallel mode. If the
computer uses a 32-bit internal structure, all the
32 bits of data are transferred simultaneously on 32
lane connections. \ Parallel data transmission is
commonly used for interactions between a computer
and its printing unit. The printer usually located
close to the computer, because parallel cables need
many wires and may not work stably in long
distance.
- Serial Data Transmission: Most data
transmitted over telephone lines use a serial
pattern.
That is, each individual bit of
information travels along its own communications
path; the bits flow in a continuous stream along the
communications channel. This pattern is analogous
to the flow of traffic down a one-lane residential
street.
Serial transmission is typically slower
than parallel transmission, because data are sent
sequentially in a bit-by-bit fashion.
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