[Simh] PDP-11: CSM bug and fix

[John A. Dundas III]

Bob and all,

I ran across what I believe to be a bug in the CSM code:

         case 070:                                       /* CSM */
             if (CPUT (HAS_CSM) && (MMR3 & MMR3_CSM) || (cm != MD_KER)) {

According to the Architecture Handbook, CSM may be executed only if 
the MMR3 bit is set AND the mode is not Kernel.  Changing the code to:

         case 070:                                       /* CSM */
             if (CPUT (HAS_CSM) && (MMR3 & MMR3_CSM) && (cm != MD_KER)) {

also has the effect of making the ZKDKB0 diagnostic much happier.

Thanks,

John
-- 
John A. Dundas III
Director, IMSS Voice & Data Networks, Caltech
Mail Code: 1-10, Pasadena, CA  91125
Phone: 626.395.3392 FAX: 626.395.2122