[Coco] deluxe rs232 pak / MPI

Tue Nov 24 20:20:48 EST 2009

On Tue, Nov 24, 2009 at 7:30 PM, Gene Heskett <gene.heskett at verizon.net> wrote:
> On Tuesday 24 November 2009, Aaron Wolfe wrote:
>>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.
>>
> The slot switch must be to the slot the pack is in at powerup unless the MPI
> has been jumpered.  If it has been jumpered, then the packs eprom should be
> pulled as there are other packs you may have plugged in that will also have
> that as an exec address.
>

hmm.  I can't get the EXEC to work even when the rs232 pak is directly
connected to the CoCo, no MPI.  Could this mean a bad rs232 pak?

I think I have to have the MPI's switch set to the slot my drivewire
rompak is in so that the HDB DOS rom loads.
Does this mean I cannot use the rs232 pak as the same time, or maybe
this just means I must wire the IRQ lines together?

>>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?
>
> I believe that most folks put it in the front slot, aka slot 1, byte
> $FF7F=00.
>

is there a setting in NitrOS-9 to tell it to set FF7F to 00?  Would
this break the drivewire rompak in another slot?  (this rom is how I
am booting nitros9)

>>do i need to wire all of the interrupt lines in the MPI together to
>>make this work?
>
> Mine has been so wired for about 22 years, excellent idea if for no other
> reason than all IRQ's _do_ get through to the cpu.  In your case, it sounds
> like the IRQ from data rx'd may have gotten through, but the slot switch, or
> the logic at $FF7F, is preventing the IRQ service routine from accessing the
> pack, which in turn clears the IRQ, so you effectively have an IRQ stuck on.
>
>>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.
>
> There is a possibility that the Aztec inverter supply in the pack has gone to
> that great retirement pasture.  Since you have the MPI, you have the plus and
> minus 12 volt supplies the chips need available in the mpi.  You have to
> remove the Aztec assembly, and wire the cards edge connector to feed those
> voltages in where the Aztec was feeding them.  ISTR I had to superglue a
> couple of strips of thin copper plate into the blank spaces to do that.
> PITA, but it works for me, and has been for at least a decade.
>
> That rewired pack will NOT work in a coco3, as the coco3 has no -12 volt line
> at all, and the load on the +12 line may be the straw that writes fini to the
> coco3's power transformer if its not actively cooled.
>

I guess that option is out, I am using a coco3.   But does that mean I
could never use the rs232 pak on a coco3, since the coco3 have no -12v
line?  sorry if I'm being dense.

>>-Aaron
>>
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>>
>
>
> --
> Cheers, Gene
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