🚀 go-pugleaf

I'm trying to use my NorthStar Advantage (a all-in-one computer) 
as a dumb terminal to a TurboDOS system.  The problem is that 
every commo package I've tried so far is too slow for any speeds 
higher then 1200 baud or so.  I want 4800 baud minimum, 9600 baud 
desired.  (19.2k? dream mode on)

I don't need *any* facilities in the way of file handling, just a 
basic terminal with editing (cursor control, clear screen, 
insert/delete line, inverse video - which are all provided by the 
video driver anyway.)

The modem7/mex overlays are not fast enough - or more properly, 
the computer does not execute the video driver bdos/bios calls 
fast enough.  The effect is characters are lost, most commonly 
one or two after a linefeed.  The 'host' TurboDOS does recognise 
the DTR line and stops output accordingly if DTR drops.  The 
Advantage i/o also can be interrupt driven (but is not under 
cp/m).

I've written a tiny commo program that does nothing but ship 
characters to/from the modem port from/to the console 
output/input via IN/OUT and bdos func 6.  All my attempts to 
control DTR to avoid character loss has been unsuccessfull.  (I 
don't know how to write a interrupt-driver or I would have tried 
that too.)

So, has anyone tried/done a hack for the Advantage to allow 
serial i/o at speed above 2400 baud?  My normal dealer says max 
is 1200 baud and won't help further.  With a cooperating host 
(i.e. acknowledges the DTR line) I'm sure higher speeds are 
possible.  But how?

bob