Ultrix 4.0's Perception of Memory Size

[Dave Robbins]

In article <11029 at bunny.GTE.COM> I write:
>I am running Ultrix 4.0 on a DECStation 3100 with 24MB of memory.  The PROM
>code recognizes and tests 24MB of memory, but when Ultrix is booting up it
>insists that there is only 12MB of memory.  Why?

I received several good followups via mail and news, and ... following the
advice of more than one respondent, I dropped back into the PROM code and
ran the self-test.  All 24MB passed the self-test, but still /vmunix insisted
that there was only 12MB of memory.  Following one suggestion, I switched off
the machine, opened up the box, and shuffled the SIMMs in the second 12MB.
When I switched it back on again, the self-test still found 24MB of good memory
(at least I didn't kill any of the SIMMs in the process :-).  But ... when I
booted /vmunix this time, *it found 24MB of memory* -- imagine that!  So, I am
now happily running with the system actually thinking it can use all of the
memory that exists on the machine.

Many thanks to all of you who responded to my query.  Collectively, your
suggestions did the trick.

Of course, I might wonder:  what is it about the SIMMs that the self-test
sees them all but /vmunix sometimes doesn't?  Oh well, mine is not to reason
why.
-- 

Dave Robbins                    GTE Laboratories Incorporated
drobbins at gte.com                40 Sylvan Rd.
...!harvard!bunny!drobbins      Waltham, MA 02254