>I now have the chance to buy yet another Zorro II RAM card (a SupraRam 2000
>populated to 4Mb this time) very cheap. The problem is that I know the 2000
>is not capable of taking more than 8Mb of AutoConfig RAM, so would I have a
>problem in my 3000 with 12Mb on cards designed for the 2000?
Yes, you would have the same problem on the A3000. The A3000 hardware
actually opens up another 1.5MB of I/O space for Zorro II use, but the
software folks repeatedly refused to tell expansion.library about
that. It's mainly an issue if you have a BridgeCard or other large I/O
device and still want 8MB. There was no way to add more memory on the
A3000's Zorro II bus, since the system areas, like Chip RAM, ROM,
motherboard I/O, etc. are in the same places as on the A2000. The
A3000/A4000 Zorro bus map looks like this:
$00200000-$009fffff Zorro II Memory
$00a00000-$00b7ffff Zorro II I/O (Unused by the OS)
$00e80000-$00efffff Zorro II I/O
$10000000-$3fffffff Zorro III (Unused by the OS)
$40000000-$7fffffff Zorro III
There's no obvious reason they OS doesn't use those mentioned areas,
except maybe to make the life the expansion.library author easier.
Cards would work properly in those areas.
Dave Haynie | ex-Commodore Engineering | Ki No Kawa Ryu Aikido
Sr. Systems Engineer | Class of '94 | "Life was never
Scala Inc., US R&D | "See us in the movie!" | meant to be painless"