[Coco] Trying to understand Cart Usage on Coco3

[Robert Gault]

RETRO Innovations wrote:
> OK, one more question:
>
> I have a 16kB EPROM on the cart port of my EPROM cart, attached to A13-A0.  If I
> turn off the ROM with ffde,0 and then read c000, does that read 0000 of the
> eprom or 1000?  I seem to recall something about the A13 line being inverted on
> ROM reads on the Coco3.
>
> JIm
>
>

That does not ring any bells. There is no indication in the CC3 service manual 
that any of the A lines are reversed; p51.

The GIME settings regarding ROMs, select external 32K ROMs or 16K internal + 16K 
external, so that should not be a problem. $C000 in memory should be $0000 in 
the EPROM. $E000 in memory should be $2000 in the EPROM.
I've programmed a custom Disk ROM so that a special Backup program resides at 
$E000, second half of a 16K EPROM. This is installed in a Disk Controller.

Robert