A couple questions on DCC decoders - can anyone help on this? Checking the NMRA specs, it seems that the ability of a DCC decoder to operate on non-DCC trackwork is not mandatory, it is only recommended. Does anyone know of any brands /models of decoders that do NOT revert to standard non-DCC operation when the track is powered with either pure DC, sinusoid pulses, or rectangular pulses (all unipolar of course)? For decoders that DO revert to standard operation under the above conditions, does anyone know if they still allow external speed measurement/control by using the motor back emf? Or is the motor back emf prevented from returning to the rails? Thanks!