[Simh] Needed: RH750 specification

[Phil Budne]

Tim wrote:
> This is a case of the *software* not conforming to the SRM, and relying
> on an UNDEFINED implementation choice.  BB* is not allowed to have an
> operand in I/O space, and the result of such an instruction is
> UNDEFINED.

I hope there is a special corner in Hell(*) reserved for people who
think C "bitfields" are a good way to do I/O register access!  Yeah,
it's a pain to read, modify and write a specific width of data, but
there's NO telling what the compiler will generate, and whether it
will work.

(*) I guess it's a sub-corner of the corner for people who say
"it's working fine for me right now"