RSTS / Simh disk drive confusion

[Al Kossow]

Best rule for SIMH or E11 purposes is
NOT to mix "RM" and "RP" drives on a single RH11/RH70.

--

There was some discussion/questions from Bob Supnik about this
on the simh developers list this week if mixed drives were or
were not supported on the PDP11 operating systems. It sounded
like they were not, so I'm surprised that they may have been 
on V9 and earlier.

The problem comes about because the RM and RP massbus controllers
have slightly different register sets.