It should not cause any issues if the boards are mapped correctly for memory. As long as they each have their own unique address, you should and can use multiple boards and more ram as fast ram. Not only was this something we did back in the day, but I have a system doing it right now as I mentioned. No issues what so ever. I can populate all that ram with a problem. I AM using only official stock boards in this machine, all z2 and no 3rd party stuff. There IS a caveat to this however.. You need a 4.6 (if I am remembering right from that far back) or better rev motherboard at the least. It might be a Rev 5 series, I will have to dig up some of my tech data from back then to be sure. Rev 6 boards should work fine and the B2000 boards, which I have one of those as well, are going to be a problem because they were never sold. The B2000 boards we gave to dealers ONLY as SHOW units because they have an inherent flaw in the design that has to do with DMA and zorro issues. So they are going to be a problem with a few things for anyone trying to use those for anything more than a standard basic Amiga system.
Pardon my skepticism, but if it's true that you have 24MB on the Zorro II bus running stable with no sneaky/subtle issues, then this is new knowledge that I think is not known in the community. Can you share a screengrab of your output from ShowConfig? That will give some basic info on the addresses involved. And it would be great if you could find and scan/share some vintage technical bulletins relating to this. I'm sure many would be interested.
I think the B2000 Zorro/DMA issues you mention might refer to rev 3.8 or 3.9? Have a look at Dave Haynie's
notes about revisions.
Another way to get around that, is z3 cards or CPU slot cards or if I remember right, there are even a couple video card slot ram cards that also work.. not sure on this latter one though but I thought I remembered seeing it available somewhere. My other machine has 128 meg ram but I am using the CPU slot for that. The stock machine, I have the 24 meg in because I am using 4096 block CF cards for the drives which eat ram and validation is an issue if you don't have enough of it, as you know.
Not just another way, I thought Zorro III and the CPU bus were the
only way to get >8MB until you mentioned your 2058 magic.
BTW, did you note I found the other problem while troubleshooting. Bad 7.0 rom burns for the two sets I bought.. Replacements are on the way so for now using my official set in one and the 8.0 set in the main machine I use.
Yup, good catch. I think I mentioned there that rev 8 ROMs for the 2091 are also not generally known, so you may want to get those dumped/shared, too.