That's a good question, and one I should have to face when deciding on my own A500 setup, which will either include the Derringer 50MHz '030 with 32MB 32-bit RAM and a GVP Impact-II SCSI, or the A530 Turbo 40MHz '030 with it's own on-board RAM (8MB max, currently loaded.)
IIRC, the GVP DMA controller can DMA into any RAM mapped into Zorro II memory space, that is, the 8MB RAM. I do not recall if that memory is required to be 16-bit or not, but it wouldn't suprise me. I think CPU cards map their RAM into either non-standard mapping or odd positioning (like my old MTec 020i) or into what would be considered Zorro III memory space.
