I managed to find on the web copies of the manuals for HP CS/80  
("Command Set for the 80s" -- used by HP-IB hard disks and cartridge  
tape drives) and SS/80 ("Subset 80" -- used by HP-IB floppy drives).

We, of course, have drivers for CS/80 disks (rd) and tapes (ct), but  
the drivers are not well-documented internally.  We do not have a  
driver for HP-IB floppies.

If anyone is interested in these, let me know, and I'll send you the  
PDFs.

-- thorpej