Any driver on a circuit that has a non-zero output Impedance requires ImpedanceMatching to deliver the maximum amount of power to the load.

If the load InputImpedance (resistance) is equal to the drivers OutputImpedance?, the power at the load is at a maximum. If there is a TransmissionLine connecting the driver to the load, it must also have a CharacteristicImpedance close to the OutputImpedance?, so as to instantaneously load the driver to the right load, to prevent ringing in the circuit. Imagine you take a TransmissionLine and make an incision, both sides of the TransmissionLine will be the same CharacteristicImpedance as the original line. This can be modeled as a amplifier with unity gain (0dB) and an InputImpedance and OutputImpedance? equal to the CharacteristicImpedance of each respective side, ensuring maximum power is transferred.

Hey. This is getting fairly far from the topic of 'linux'; could you please at least remove all the wikiwords and define these terms on the same page? - zcat(1)

IMHO, It's kinda on topic as it interests people that are trying to maintain Unix machines, mostly in understanding why you need Bus Termination (SCSI anyone? ThinNet?), and other related things (Why are there 3.3v PCI cards?). Lets see what JamesSpooner adds, and perhaps look at condensing it/removing irrelevant material in a few months if it's not used. -- PerryLorier