Re: commodore 8000 extension above the $8000-$8FFF or $E800-$E8FF

Den Sun, 18 Feb 2018 22:11:53 +0100 skrev didier derny
<didier@aida.org>:
> Is there many extension above the area  $8000-$8FFF and / or
> $E800-$E8FF ? there is the 64k ram extension
> is there any other board ?  superpet ?  madison zram ?
> 
> I made a vga board for the commodore 8000...
> this board works fine with the base 8032 board
> for the 64k extension I'll add it directly on the vga board
> 
> I'm trying to list what could make the vga board fail
> the board works by capturing the write in the screen memory
> it also capture the write in the io area to reconfigure the output in 
> case of video configuration change...
> 
> one solution is perhaps to add 2 wire for the cs  screen ram / io area
> (for example I don't want to capture a write in $8000 but in the 64 
> extension)

IIRC you can with some jumpers use signals from the user port to map in
the last 32k of the 128k in an 8296 in some places above $8000. (Part
of that 32k space is always used as video ram).

I'd suggest reading the 8296 manual/supplement and check the
schematics. There are two versions of the schematics, the old from
funet is almost unreadable, while this version is good:
http://6502.org/users/sjgray/temp/CBM8296_ServiceManual_DinA4_alle.pdf

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