Both [IPX and SS20] are 8bit SE
Right but low voltage or high voltage? :)
What I was trying to say before was: I don't think there was ever
SE-Low Voltage; that (as far as I can remember) never existed.
That matches my understanding too: all SE is the same voltage - the HV
versus LV distinction exists only for differential (and LVD is usually
(always?) willing to fall back to SE).
There certainly could be a different-voltage single-ended device
somewhere, but it would surprise me, since it wouldn't interoperate
with the rest of the single-ended SCSI world.