A2091 and Zorro-II DMA memory

[Zac67]

Memory is required for DMA to work (=Direct Memory Access) - the A2091 works with chip RAM as well. Extended RAM (beyond 16 MB/24 bit address space) can't be addressed so it's useless.

[Zac67]

...,  and the 4 GB limit of PCI etc. I guess 64-bit systems have a bit left before they need this technique

That's what we once thought of 32 bit, too...