[vardump]

I had a weird Amiga 500. It had late OCS chipset, but on hardware level its Denise could display bitplanes from slow RAM (512 kB RAM expansion)! Unfortunately I never tested blitter, copper lists, sample playback etc. from this memory range, so no idea whether those worked as well. Of course all is DMA access, so my guess is they would have.

RAM was mapped at 0x80000-0x100000 from chipset point of view. CPU saw same data at 0xc00000-0xc80000.

[snarfy]

Yep, I had the 500 too. They called the updated chip Fat Agnus.