[Coco] GIME questions

[Robert Gault]

David Gacke wrote:
> 
> 
>>Actually that is not the case. The code from Begmove ($C03F) through 
>>Endmove ($C36C) is copied.
> 
> 
> Right, this is what I "should" see, but I'm guessing I've got the GIME
> misconfigured somehow.
> 
> I know I'm seeing the ROM at $4000 as well because when I try and write
> over it, it doesn't care. The values don't change.
> 
> 
> I'm just not quite sure how to configure the GIME to do this
> intentionally.  What I was hoping for was an answer of:
> 
> 
> Here, jam this X value into FF90, and these X values into FFAx, then jam
> this other value into FF90 and you'll see the scenario you're talking
> about....
> 
> 
> Since we're on the GIME, can you modify the FFAx registers while the MMU
> is enabled?
> 
> Anyway, thanks very much for the advice. It's good to have a list where
> someone will tell me how I'm wrong when I actually need it!  :)
> 
> 
> 
> Dave
> 
> 

I'm not sure if you can move the ROM's to the $4000 location in memory. 
If it is possible, you would need to set either $FFA2 or $FFAA to $3E to 
make $C000-$DFFF echo there. Problem is there is no switch to convert 
$0-$7FFF to ROM.

If you really are seeing ROM's at $0-$7FFF, you are not emulating the 
GIME correctly. There is also no method in the specs for making a SAM 
MC6883 put ROM in the lower half of memory.