At least the older Xircom adapters can work in nybble-mode with a uni- directional port. I just didn't think they'd break it with the newer models. I want a PE3, not PE2 because of power consumption - the PE3

can be powered off of a parasitic cable (typically from the keyboard jack, but there isn't one on an XT laptop; I was just going to wire one in). There are parameters you can tell the PE3 to use when connecting