Well, OK, I'm dredging up an old thread, but I thought I'd give an update.
Also, I'm considering moving my board to an Alpha, thus the crosspost.

On Fri, Sep 29, 2000 at 10:36:10PM -0400, Thor Lancelot Simon wrote:
> The 16650 is a StarTech (now "Exan" or something like that) part.  They
> also make the 16850, which is like a 16650 with some more useful features.
> Both have automatic control of RTS/CTS triggered by a threshold FIFO level,
> which is a major, major win at high speeds.  These require some special
> support in the driver, and I'm not personally convinced that the 16650 
> support in our "com" driver actually DTRT at the moment (it did once).

I've been using my 4-port 16650 board for since perhaps October 2000. I
haven't seen a single dropped character in all that time, which is pretty
nifty on a 486SX/33. 

I was kinda annoyed that I had to track down the undocumented config
file option "options COM16650" before the board was probed as a 16650
instead of 16550. 

My config file has this in it:

options		COM16650
com0	at isa? at port 0x3f8 irq 4
com1	at isa? at port 0x2f8 irq 3
com2	at isa? at port 0x3e8 irq 5
com3	at isa? at port 0x2e8 irq 9

Works like a champ. Can we enable the COM16650 option by default now?

Incidentally, if I wanted to add two more serial ports then where is
the "standard" place to put them? Where would MS-DOS expect to find
"COM5" and "COM6"?

Alternatively, if I moved the board to an AXPpci33 (which already has
two serial ports) then where would I put the highest 2 serial ports?

Thanks.
-- 
Kevin P. Neal                                http://www.pobox.com/~kpn/
           On the community of supercomputer fans:
"But what we lack in size we make up for in eccentricity." 
  from Steve Gombosi, comp.sys.super, 31 Jul 2000 11:22:43 -0600