Another issue with the 750, 730, and 8600 is that they are not as exact
at the 780 and CVAX simulators, because certain critical documents
(microcode, some subsystem specifications, some schematics) are not
available. For example, the 750's simulated Massbus and Unibus adapters
started out as clones of the 780s and have received only minimal
modifications. Both simulated versions contain <too much> logic and
error checking; the 750 was done with 400 gate TTL gate arrays, and
gates were precious. VMS is not sensitive to the remaining differences;
other operating environments might be. (For example, the 750 didn't
check that register accesses were longword and aligned, and this was
used in both the 750 boot ROMs and the diagnostic supervisor.)
For the 750, the UBA750 spec is online (although the register
descriptions in it are obscure). The RH750 register secs can be inferred
from the Emulex workalike, the SC750.
/Bob
_______________________________________________
Simh mailing list
[email protected]
http://mailman.trailing-edge.com/mailman/listinfo/simh
