> 	Having got a pc with 16550's for the express purpose of
> driving serial ports at high speed, I am a tad dismayed that I'm
> getting silo overflows on the system.

Me too, me too. :-(  My system is a P120 with 16550a UARTs.  I get
_lots_ of FIFO overruns at 57600 bps with PPP.  I was going to run
at least six ports at this speed, but using one causes way too many
errors already. :-(

I guess that old A2232 serial card on the Amiga was pretty good -
I'm still running 6 ports at 38400 with _no_ problems on a slow
68030 system (which performs much better than a 20 times faster
Pentium, it seems).

Should we lower the FIFO treshold?  Is there some other trick?
At 57600 bps and FIFO treshold at 8 bytes, the system should have
1.38 ms time to service the interrupt.  WHAT is the Pentium
doing for so long? ;-)  I would think the CPU runs some 100,000
instructions or more in that time.  I wonder what instructions -
the machine is completely idle, other than running ftp and PPP.

Any ideas?

  -jm