I haven't been following this thread too closely so I may have missed something, but it seems to me that the proposed solutions are overly complex. One simple solution that comes to mind is to define a set of vendor unique SCSI commands, one for each of the registers in the IDE command stack and then do all the emulation in the device driver on the host side. The interface card is just then a simple state machine; really simple if u make it a non arbitrating protocol implementation and use PIO for data transfers (SCSI-1 lives :-). Tom