Difference between serial and parallel data transmission


The parallel data transmission refers to transmission of binary data simultaneously (usually 8 bits at the same time), while serial data transmission refers to transmission of binary data one bit at a time.

Serial data transmission

In serial transmission data is transmitted one bit at a time.

The cable needs one pair of wires to transfer data – one wire to receive, and the other to send the data.

Serial Communication

The serial transmission is cheaper but it is slower than parallel transmission. In general, serial transmission is preferred over parallel transmission when there is a need to transfer data over long distance. The cable used for serial transmission is called Serial cable.

Serial Cable

An external modem is the example of a device that sends and receives data via serial transmission/communication over the telephone line. The points or ports on the computer where serial cable is connected are called Serial ports or COM ports.

Parallel data transmission

As compared to serial transmission, parallel transmission is fast and transmits more data (usually 8 bits) at the same time.

Parallel data transmission

It is more expensive as compared to serial transmission since each bit must have a separate path. To accommodate this each bit has its own wire inside the cable. In this way a parallel cable has eight wires. This type of cable is easily affected by noise and distortion. Printers are examples of devices that uses parallel ports for the transmission of data. 

Parallel port on computer

Parallel cable for printer

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