Parallel communication is a method of sending several data signals simultaneously over a communication link at one time. It comprises of several wired channels in parallel.


Parallel Communication

The basic difference between a parallel communication and a serial communication channel is its quantity of various wires in the physical form that is taken into use for communication of data between different devices. In contrast to serial communication, Parallel communication uses more than one wire ( and that is excluding the ground wire).

Examples of parallel communication systems

  • ISA
  • ATA
  • SCSI
  • PCI
  • Front side bus

And many more …

Parallel communication - scsi Parallel communication - PCI

Parallel communication_ISA                          Parallel communication - eisa

  Comparison with serial links

Before the development of high speed serial technologies, the selection of parallel links against serial links was decided by the below mentioned factors:

(a)        Speed of data exchange: The data exchange speed of a parallel data link is equivalent to the multiplication of the number of parallel paths and the number of bits processed at a unit time.

(b)        Cable length: As the length of cable increases, so does the amount of metal wires. This increases the chances of Crosstalk. Crosstalk means interference between the cable wires and it leads to the unsuccessful exchange of readable data (garbage value). Due to this effect, we can not increase the length of cable beyond a certain safe limit. Due to this, the cable length supported by a parallel link is quite shorter than serial links.

 (c)        Complexity: Parallel data links are relatively easy to installed in hardware, which in turn makes them a reasonable choice. The configuration of a parallel port in a PC is quite easy as compared to its counterpart ‘Serial links’. It is because almost all serial links are requires its conversion into a parallel form using a Universal asynchronous receiver transmitter to enable it to be connected with a data bus directly.

The decreasing cost of integrated circuits and the increasing consumer demand for more data exchange speed and length of cable has led to parallel communication links becoming deprecated in favour of serial links; for example, IEEE 1284 printer ports against USB, Advanced Technology Attachment against Serial ATA, and SCSI against Firewire.