this is a well document problem on netbsd sparc.  check the archives
for the past year and you'll see several posts (some from myself)
about this.  as far as i could determine, there were 2 points where
it became worse.  sometime between october 2 and october 19, 1996,
and then again around december 30, 1996.  i looked and looked and
looked at changes but i wasn't able to find anything.  charles
hannum fixed some splhigh()'s to be some lower value about 6 months
ago, and the problem became less severe, but it still exists.  i'm
currently able to run my SS2 serial port (ttya) at 38400 bps but
i have a dedicated machine -- it does little else except act as a
router for me.


i haven't yet tried out the new zs code gordon contributed.