I would have considered that had these been anything special, but I got a bunch of these adaptors from my dad's dental office when they were moving off of their Xenix system (with the Xenix system as well). They are not wired to any standard I know of, and they don't even seem to be wired to the same standard within the lot. I remember fervently wishing that they had used a MicroVAX instead of a PC with SCO. I also wished that I had been paying attention when they were getting rid of the Altos, but that was when I was in 4th grade.