> > Well, the Cyclades cards use a chip which only has 12 bytes of FIFO for
> 
> Ouch! That's less than a 16550. Perhaps that explains why the
> Cyclades card was cheaper than the 8-port (and even some of the 4
> port) 16550-based boards I've seen.

Dunno.  The automatic hardware handshake makes the Cyclades better than a
normal 16550, IMHO.

> > On the other hand, if you swap the DTR
> > and RTS wires in your serial cable, the Cyclades hardware can automatically
> > negate RTS before the FIFO overruns.
> 
> So the Cyclades has the ability to turn off DTR automatically when
> a FIFO is about to overrun? How odd. Is this settable per-port? Or
> do I end up with a modem that hangs up if it overruns if I don't
> have an extra cable with DTR and RTS swapped, and have to use a
> normal cable instead?

The driver has a global setting for this, but it is settable either per-port
or per-4-ports in the hardware (can't remember).  I recommend using a special
cable and enabling the option..  When the option is disabled, RTS and DTR
work like you'd expect - but RTS is under software control, so if your CPU
gets too busy, you may lose data.

  -jm

-- 

                     ---> http://www.jmp.fi/~jmarin/ <---