Originally Posted by Al Kossow
is the pro hard disk controller schematic somewhere?

Apparently not. There's schematic of second clone, though: http://www.emuverse.ru/downloads/computers/DVK/docs/kzhd.djvu

The story, apparently, is that once Pro got cloned (with its disk controller), the design was reused in the DVK series, as a Q-bus controller. That document is for the DVK one.