[Coco] deluxe rs232 pak / MPI

[Aaron Wolfe]

Hi,

I just acquired an rs232 pak and MPI.  The MPI seems to work fine with
my coco 3, at least my drivewire rom pak works fine through it.
I haven't been able to get the rs232 pak to work in basic or nitros9,
with or without the MPI.  I have the original documentation from
tandy, was wondering if things have changed for use in the coco 3.
Also I have the 6309 instead of 6809, maybe this has some effect.  The
MPI is 26-3024 "updated for use with the coco3".

the docs say to do "EXEC &HC000" or "EXEC 49152" to access the setup
routine in the pak's rom.  This results in various lockups on my coco
3.

looking through the nitros9 source I see that FF68 is base address for
T2, and FF6C for T3.  Tried both with basically the same results.  I
see there is a compiler flag for MPI usage, it is set.  I am not able
to try nitros9 without the MPI because currently I must boot from
drivewire  (really looking forward to that SD card pak, if you're
listening Roger :).  the rs232 pak does not appear to have been opened
for any modifications, label covering the screw was intact until I
opened it just now to look for obvious bad components.

when I "iniz /t2" or /t3, sometimes I get error 246, sometimes it
works.  when it works, an irq routine shows up in the "irqs" command
and the device is listed in "devs".  however, all attempts to pass
data do not seem to work.  sometimes the coco locks up about the same
time data is sent into the port, so I assume this means something
somewhere is working, sort of?  might just be coincidence to be
honest.

should I put the rs232 pak in a specific slot of the MPI?
do i need to wire all of the interrupt lines in the MPI together to
make this work?  saw some posts about that.
any tests I can do in basic, with the rs232 pak directly connected?  I
saw a post about peeking values, they said:

> ?PEEK(65384) usually reports 0 initially
> ?PEEK(65385) usually reports 16 initially
> ?PEEK(65386) and ?PEEK(65387) should report 0 initially

the answer in the thread was that the user doing the troubleshooting got:


?PEEK(65384) 0
?PEEK(65385) 112
?PEEK(65386) 0
?PEEK(65387) 0

I also get exactly these results, if that means anything.

Basically I am not sure if the rs232 pak works, it was in storage for
many years.  I am completely new to using an rs232 pak or an MPI, and
actually new to OS-9 as well, so there are a huge number of unknowns
here.  any hints or recommended practices are much appreciated. I'm
not sure what tests to do to start eliminating possibilities.

-Aaron