 In general, one of the two signal lines is driven to −0.32 V ± 20%, while the other carries 0 V. This, itself, could be considered as two differential signals of ±0.16 V superimposed on a −0.16 V common mode level.However, to provide preemphasis, for the first 250 ns (1/4 bit time) after a signal is driven low, the negative signal line is driven to −1.6 V. During this time, the common-mode voltage is −0.8 V.

This signal is designed to provide a minimum of ±100 mV at the end of 152 m (500 feet) of cable.The two wires are denoted A and B.