<> > [...] dma address is Registers 0/1/2 [...]
<>    
<>    As I have shown above, these are always initialized to all zeros,
<> proving that HDC9224's ability to address 16 MB is not used in BabyVAXe
<> and all transfers have to go through a special buffer.

Init'ing them to zero is indicitive of nothing.  Depending on how many
DMA address bits are actually used it only means the DMA will start at
address 0 of buffer at offset(mapped?).

The real question was is there another address loaded somewhere else
and also is the transfer length loaded some where else other than the 
9224?  If they are only loaded to the 9224 then the operation is
exclusive to the 9224. If they (dma address and xfer length) are loaded
to a non 9224 register then there is external logic that must be resolved.
The NCR5380 has neither a transfer length or a DMA address register so
it will transfer whatever the PIO or DMA says to.

Allison