[Coco] GIME questions

[Robert Gault]

David Gacke wrote:
> Hi Robert,
> 
> Here's the setup I've got. I've got a daughterboard I made jammed into
> the 6809 socket of my CoCo 3. Then I have a ribbon cable back to my
> dsPIC demo board with a 30F6014 on it.
> 
> Connected to that, I have a Microchip ICD2 pod for downloading new code
> into the microcontroller.
> 
> The CoCo 3 itself is a stock model with 512K of RAM.
> 
> But from what you're saying, maybe I have a high order address line
> hosed up or something.  I'll double check those again with the scope to
> verify.
> 
> Who knows. Maybe I've just got bit addr15 and addr14 shorted or
> something goofy.
> 
> 
> Thanks for your help.
> 
> Dave 
> 
 ><snip>

I was about to suggest the same thing. Why don't you scan memory from 
$0-$7FFF in both normal and 32K ROM mode and see if the ROMs echo in the 
$0-$7FFF region. If they do, then both your high order bits and RAM/ROM 
selection isn't working correctly.

It is a result similar to a 128K Coco3 when the MMUs are set to $00. 
Some early programs needed to be rewritten when 512K boards showed up 
because the programs ignored bit high order MMU bits.