[Coco] Coco 3 Memory Map Questions

[Darren A]

On Thu, Feb 11, 2016 at 10:51 AM, Dave Philipsen wrote:

> I would have to agree with Darren.  However, since the chip select of the
> ROM is controlled by the GIME it is possible (although not likely) that the
> GIME could cause something other than the ROM contents at 7FFx to show up
> when the CPU addresses FFFx.



The GIME, through control of the ROM's chip select, obviously determines
which addresses the ROM will respond to. It cannot however alter the
address being presented to the ROM on A0-A14.  To map a CPU access of $FFFx
to the $BFFx locations ($3FFx inside the ROM) the A14 address line would
need to be inverted. There is nothing on the address bus between the CPU
and the ROM to do this.

It is possible for the GIME to map the vectors to $7FFx, but that is not
what we are talking about.

- Darren