Advance work for UBA update

Define some UBA and IO addressing macros.
KDP Update

o Split hardware and microcode initialization to more closely model hardware
o Implement maintenance registers used for microcode loading so more creative versions work.
o Handle RSX's non-segmented data messages (it computes header CRCs.)
o Halt the KMC on OS errors; give each a unique halt code to debug.
o Handle power-up RESET differently to account for RAM structures that survive bus reset.
o Do less in master clear - it does not initialize most state.
o Add RSX's variant of COMM IOP-DUP to the known microcode list.  (Still need to determine version.)

RSX now talks to TOPS-10 DECnet Phase IV - KDP - KDP.