Forced-Perfect terminators force the impedance of the cable to match each device through diode switching and biasing. The set of signals for Single - Ended devices is very different from the signals for Differential devices. Single - Ended cables connect up to eight drivers and receivers. A 50 conductor flat cable or 25 signal twisted-pair cable should be used. A stub length of no more than 0.1 meters is allowed.
Differential cables connect up to eight Differential drivers and receivers.
A stub length of no more than 0.2 meters is allowed. Ideal impedance match is 122 Ohms. However, cables with such high characteristic impedance are not usually available. Trade - offs in shielding effectiveness, characteristic impedance, cable length, number of loads, transfer rates, and cost, can be made to some limited degree. To minimize discontinuities and signal reflections, cables of different impedances should not be used in the same bus.