[Coco] MPI writing to $c000

[RETRO Innovations]

On 1/24/2016 8:44 AM, Robert Gault wrote:
>
> I doubt I can help with your PAK but the obvious issue that comes to 
> mind is whether you have set the MPI data at $FF7F correctly so that 
> your external ROM/RAM has access. After all, your device works when 
> directly connected to a Coco. :)
I hav put a scope on the WE line, and I am seeing the trigger, so I 
believe the correct slot is selected.
>
> The high nibble at $FF7F selects the MPI slot for RAM/ROM. The low 
> nibble selects the slot I/O at $FF40-$FF5F.
>
> Perhaps you meant that even with the MPI set to the correct slot for 
> your cart the RAM is not working. If that is the case, are you having 
> failures with any other cart that contains a ROM when plugged into the 
> MPI?
All my MPI carts ROMs read fine.
> If your device is unique in having MPI problems, then look for wiring 
> issues using a Coco schematic showing the expansion connections.
Jim