The Busbus-Invertinvert method generates a code that has the property that the maximum number of transitions per time-slot is reduced from n to n/2 and thus the peak power dissipation for I[[input/Ooutput]] is reduced by half. From the [[coding theory]] point of view, the Busbus-Invertinvert code is a time-dependent Markovian code.
While the maximum numHamming distancebernumber of transitions is reduced by half, the average number ofhas transitionsa is not thatsmaller gooddecrease. For an 8-bit bus for example, the average number of transitions, using bus-invert coding becomes 3.27 (instead of 4), or 0.41 (instead of 0.5) transitions per bus-line per time-slot. This means that the average number of transitions is 81.8% asof comparedthe number with an unencoded bus. ThereThis areis twobecause reasonsthe invert line contributes some transitions whyand the performancedistribution of the Bus-InvertHamming codingdistances foris decreasingnot theuniform.<ref>M. averageR. numberStan ofand transitionsW. isP. notBurleson, as“Bus-invert good ascoding for decreasinglow-power theI/O,” maximumIEEE numberTransactions ofOn transitions:VLSI Systems, Vol.3, No.1, pp.49-58, 1995</ref>
* The invert line contributes itself with some transitions.
* The distribution of the Hamming distances for the next data values is not uniform.<ref>M. R. Stan and W. P. Burleson, “Bus-invert coding for low-power I/O,” IEEE Transactions On VLSI Systems, Vol.3, No.1, pp.49-58, 1995</ref>
