And the conclusion for the Cyclades card and NetBSD 1.5.

I spent the afternoon and evening trying to get it to work, and then
poking around in the source trying to figure out why getty would
work, but pppd would not.   Pppd can answer the phone, and do initial
negotiation, but the networking always fails, complaining of the TCP address
on both ends of the connection being zero.

As far as I can determine from the source (I'm not really all that familiar
with the internels) the Cyclades Y simply does not have the appropriate
driver machinery to support the ppp device.  In particular, it does not
support a number of the ioctl/tcsetattr calls that are needed to make
the card useful for ppp.  It also lacks the stuff that gets invoked on
setting the "Line Discipline".

(If anyone out there could give me a nutshell explanation of how this works...)

I can use it to do a getty at 57600, and it seems to work fine, but
pppd does not work.  As far as I can tell, this is an inadequacy of
the driver/tty machinery.  Again, as far as I can tell, the tty
"device" has to be taught to talk to the "cy" device, and speak
PPP line discipline, and that has not been done.  When you use it in
serial apps, it is just a character device, not a "tty".

Looks to me like it would be a non-trivial amount of code to get it
working the way I would like.

Bummer.

-dgl-