Sounds about right. VMS is the only OS (that I know of) that uses all 4 processor privilege modes. Side note: The 21064 has such bizarre IPR mappings, the rea

Sounds about right. VMS is the only OS (that I know of) that uses all 4 processor privilege modes. Side note: The 21064 has such bizarre IPR mappings, the read values have lots of bits scrambled around compared to their write counterparts. This is likely a hardware design decision affecting the programmer's model, if I had to guess.