Special thanks to forum member t-rexky for sending in the datasheet for the NCR 53C9X SCSI Controller!
http://www.nextcomputers.org/NeXTfiles/Docs/Hardware/Datasheets/SCSI_Controller/NCR53C9X_Datasheet.pdf
oh wow. I havent visited the site in ages. Im amazed to see this file finally was found :D nice.