mchk 2 --- tbuf error on 750 running 4.2 BSD

[David C. Martin]

In article <654 at gatech.CSNET> spaf at gatech.UUCP (Gene Spafford) writes:
>In article <83 at zeta.UUCP> jeb at zeta.UUCP (John Berry) writes:
>>
>>We are running VAX 11/750's with UNIX 4.2 BSD. We have just had DEC
>>install REV 7 of the L0003 board, which we hoped would clear up the
>>mchk 2 --- tbuf error problems. Well it has not. Can anyone out there
>>in network land give me any insight to what is happening. DEC cannot
>>find any problems when they run diagnostics. 
>
>This is an old and frustrating problem.  I've had it show up on at least
>4 750's I've worked with.  The problem is, indeed, with the L0003
>board.  Let me tell you how it has been explained to me (if anyone has
>a more detailed explanation, please let us know).

Okay, I will.  I already mailed John, but perhaps this could be rehashed
one more time.  The problem does lie in the L0003 board, but the solution 
is easy.  VMS has microcode to alleviate these parity problems, and 
using the /boot program which reads microcode off the disk, the problem
can be easily solved.  Mike Karels wrote up a patch and we have been running
it at UC Berkeley for quite some time with favorable results.  If there is
sufficient need, I will dig this up for those of you who need it, the microcode
loading program was previously posted to the NET, so check your archives for 
that.

-- 

David C. Martin - Sun Microsystems / UC Berkeley
uucp: ..!ucbvax!sun!dcmartin                   usps: 2280 California St #8
arpa: dcmartin at Berkeley                              Mountain View, CA 94040
at&t: 415/960-7458 (O) - 415/967-0506 (H)