Hi all,
  The relevant documentation is "MSCP Basic Disk
Functions Manual",
 AA-L619A-TK, and "Storage System Diagnostics And Utility Protocol",
 AA-L620A-TK, which in turn are parts of the UDA50 Programmer's
 Documentation Kit (QP-905-GZ).  My copy is version 1.2, April 1982. 
anyone has this documents here, and don't need it anymore ?
thanks,
emanuel