Serial Transmission vs Parallel Transmission

This page Serial Transmission vs Parallel Transmission describes difference between Serial Transmission and Parallel Transmission.

There are two ways one can transmit binary data i.e. serial and parallel. In Serial Transmission, each bit is transmitted one after the other. Say letter M having ascii value of (msb)1,0,0,1,1,0,1(lsb) will be transmitted 1 bit at a time. Here LSB is transmitted first while MSB is transmitted at the end.

As the transmission is sequential, it takes long time to transfer all the data. Serial transmission is preferred for long distance application. There are ways to convert from parallel to serial and vice versa based on need. The shift register circuit is used to convert from serial to parallel and from parallel to serial format.

Serial Data Speed

Data rate (bps) = 1/Tb
Tb is the time duration of 1 bit
If the bit duration is 2ms then data rate is 1/2x10-3 , which is about 500 bps.


serial transmission vs parallel transmission

Baud rate

Baud rate is defined as no. of signalling elements(symbols) in a given unit of time (say 1 sec).

In parallel transmission, all the data bits are transmitted one at a time from one place to the other using either latch or a flipflop or using bus or using parellel connector as per need/application.

Here speed of data transfer is very fast but distance is limited. For long distance communication it requires more wires(one per bit) and hence not practical to use it due to more cost.

Following table summarizes important difference between serial transmission and parallel transmission types.


Specifications Serial Transmission Parallel Transmission
Number of bits transmitted at one clock pulse 1 bit n bits
Number of lines required to transmit n bits 1 line n lines
Speed of transfer Slow Fast
Cost of Transmission Low, as one line is needed for transmission. High, as n lines are needed for transmission.
Application used for long distance communication between the two computers. used for short distance communication. For example, between computer and printer.

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