Maybe the answer then is to jumper the 8-Up board to provide just 2 meg. That would give me a total of 6 meg which would still let me use the Bridgeboard (which I'm using to help debug another retro project - an old 386-SX) but still provide 2 meg to run the Amiga side.
That might work. The original 68000 was very limiting in address space so only 8MB was designated to Zorro II space. The A2630, 8-up, Bridgeboard and any other boards in your Zorro II slots all want to share that same space. Many other accelerators, like GVP, have a jumper to address it's memory outside of Zorro II space which is physically possible because the 68030 has a much larger address space and it's memory doesn't have to go through the Zorro II bus. Unfortunately, C= didn't make very good accelerators. You will have to squeeze all your memory into that 8MB address space unless you upgrade to a more advanced accelerator.
Or is there some code I can run to fool the system into thinking it's only got a certain amount of fast ram? Then I could just leave the 8-Up board as is.
No. I don't think it's possible. The 4MB on the A2630 with 4MB on the 8-up is all that the A2630 supports according to the original documentation. There may be a hack or ROM upgrade for the A2630 to map it's 4MB outside of Zorro II space that I don't know about. It would also be possible to add a ACCESS 32 or DKB 2632 ram expander and disable the 4 MB but it would probably be just as cheap and easier to find a better accelerator (maybe with SCSI and supporting 16MB+ outside Zorro II space) as they are pretty cheap now days. You might list your location to see if anyone local has better "cheap" hardware.
