I doubt if it's a custom inferface as the interface card also supports floppy drives and hdd's. Seems like it is a simple controller card (without com/lpt ports) with the additional CDROM audio feature.
I/O address 220 is used by the Soundblaster card in the system (SB16). That was indeed the stardard setting for those cards.
The drive: Aztech CDA 268-01A IDE (2x). Yes, that's strange: hooking an IDE CDROM up to an IDE controller makes the system crash.
Oh btw... my SB16 only has the IDE/ATAPI interface. The print does have holes for Panasonic/Creative CDROM drives, but there aren't any pins soldered in. On the other hand, this Aztech drive should be a regular IDE one, despite of the controller card that came with it (makes sense as the card/CDROM came from a 386 and those didn't support >508MB fs).