rwl++++ A1T2L - DMA Source Address for Channel 2 low byte
rwh++++ A1T2H - DMA Source Address for Channel 2 high byte
rwb++++ A1B2 - DMA Source Address for Channel 2 bank byte
bbbbbbbb hhhhhhhh llllllll
This specifies the starting Address Bus A address for the DMA transfer,
or the beginning of the HDMA table for HDMA transfers. Note that Bus A
does not access the Bus B registers, so pointing this address at say
$00:2100 results in open bus.
The effect of writing this register during HDMA to the associated
channel is unknown. However, current theory is that only $4324 will
affect the transfer. The changes will take effect at the next HDMA
init.
During DMA, $4322/3 will be incremented or decremented as specified by
$4322/3. However $4324 will NOT be adjusted. These registers will not be
affected by HDMA.
This register is set to $FF on power on, and is unchanged on reset.