I coded the AppleTalk stack for Apple's A/UX a year or two before the above conversation (I don't know if my code ever got used more widely at Apple) - it was a

I coded the AppleTalk stack for Apple's A/UX a year or two before the above conversation (I don't know if my code ever got used more widely at Apple) - it was all STREAMS - and pretty easy - create a DDP mux layer, open a stream on it (allocating a socket number), push an ATP module on that - you have an ATP connection - push a remote login protocol extension on that, then push a line discipline on that - all like plugging together lego bricks. You could replace DDP with UDP and do the same thing. STREAMS really was the cool thing at the time (if you were in the SystemV camp, if you were in the BSD camp it was the enemy - A/UX had both :-)