Parallel Communication

Parallel communication takes place when the physical layer is capable of carrying multiple bits from one device to another.This means that the data bus is composed of multiple data wires,in addition to control and possibly power wires,running in parallel from one device to another.Each wire carries one of the bits.Parallel communication has the advantage of high data throughput,if the length of the bus is short.The length of a parallel bus must be kept short because long parallel wires will result in high capacitance values and transmitting a bit on a bus with a higher capacitance will require more time to charge or discharge.In addition,small variations in the length of the individual wires of a parallel bus can cause the received of data bits at the different times.

Such misalignment of data becomes more of a problem as the length of a parallel bus increases.Another problem with parallel buses is the fact that they are more costly to construct and may be bulky,especially when considering the insulation that must be used to prevent the noise from each wire from interfering with the other wires.For ex:-a 32 wire cable connecting two devices together will cost much more and be larger than a two wire cable.In general,parallel communication is used when connecting devices resides on same IC,or the devices that reside on the same circuit board.Since,the length of such buses is short,the capacitance load,data misalignment and cost problems mentioned earlier do not play an important role.