In article <199701190310.WAA00251@madness.tmok.com> you write:
> ok, something just popped into my head while i was taking i shower.  when
> i setup PPP on my i386 w/16550 running Linux i had to throttle the serial
> port down from 115K to 38.4K because 38.4K got me better speeds.  i guess
> even with the fancy hardware kludge called a 16550 FIFO an ISA based 386 
> can't handle high speed serial communications.  if i had remembered that
> when i started asking about all this my question would have been answered
> by me myself.  but, i learned a lot in the process, so it wasn't all bad.
> 
> yea, i am definitely going to put the modem on one of the SUN 3/180's

Um, it's a bad idea to assume that just because the 16550 isn't all
you'd like that the Sun serial ports must be better.  In fact, Sun
serial ports are notoriously sucky, and if you've ever read the manuals
for the Zilog chips that Sun uses, I don't think you'd call the 16550 a
kludge -- it's really quite clean by comparison.

I'm running an ISDN net connection at 57.6 on a 25MHz 386 with
reasonable success, while my 3/60 (20MHz vs 16 I think for the /180)
couldn't keep up with 38.4 under SunOS.  I think NetBSD is better, but
not by much. A Z85230 would likely help, but what it adds is the same
thing a 16550 gives you: a larger FIFO. And it's not as large, and not
as well designed, from what I gather.