More than 128 mB on a CSPPC?

[omnicron10]

I believe the biggest problem with more ram on a CSPPC or MKIII is the fast slot on A3000 and A4000 can only address 128mb of ram.  I don't think there are physically more address lines that can be used to allow the A3000/A4000 to access more than 128MB even with 060 on the CPU card.  It also might be an issue with how the expansion library works with the fast slot to add ram to 32 bit space.  If it is not a hardware issue, it might require patching OS ROM functions to allow them to support more than 128mb on the fast slot.   The best option I could think of that might work would be a Z3 board that connections to a fast slot CPU card that allow the additional config of memory over 128MB of ram on a a fast slot card.  The actual Z3 bus would not have to actually have the ram on it but a few of the signals and allocation functions could work that way and the actual memory would be local on the fast slot for the data transfer.  Not sure that would work but if it is a hardware issue then that could solve it.  Just an idea.

[omnicron10]

There might not be a limit if you patch exec or other functions like they had to do with the Vampire 2 on the A600 (and A500 I believe).

It was stated on http://www.apollo-core.com/knowledge.php?b=5¬e=2047&x=1&z=L4DAbc that there is no physical limit.  What exactly that means is not clear.  Software or electrical is still possible.

[omnicron10]

According to this, the slot has all address lines.

http://www.thule.no/haynie/systems/amiga3k/docs/a3kcpu.pdf

Local bus slot memory doesn't use autoconfig and only 128mb was reserved, however I'm sure it would have been possible to have worked round that if that hadn't seemed like a ridiculous amount of memory when the cpu cards were designed. If I were designing an accelerator today then I'd have 4gb of ram soldered to it and then have the rom on the cpu card wait until everything else had been autoconfig'ed and then map all the unused address space as ram.

Good find on the PDF. I remember seeing that before.  I was looking for it again.  The fast slot looks like it is just and extension of the 030 bus.  I still think patching the KS will be needed to support more than 128mb of ram on that bus.  From reading posts on the zorram and DKB and other large Z3 memeory expansions, there are a lot of bugs in expansion.library that will require fixing to make things happen easily.