Well, I'm trying to emulate this ancient SCSI adapter for a long time, and has got some progress, however, I'm stuck in a phase that the doc doesn't mention at all or badly documents it.
The part where I'm stuck is: where does it fetch the CDB buffer contents? Via DMA? If so, how? It's not like IDE I guess (which does it in 0x1f0 and 0x170).

If anyone is willing to help me, it would be greatly appreciated, thanks.