> I don't know how the 5000/240 (or any other model) handles mixed
> SIMM sizes, so I'm not sure how the memory would look in those cases.

I have "Personal DECstation User's Guide" at hand, and it refers to
SIMM module installation procedure at chapter 9.  In page 9-4 I can
see a caution statement as

     CAUTION: The connectors in your system unit must all contain
     the same type of memory module: either 2-megabyte or 8-megabyte
     modules.  Your system won't work properly if you mix the two
     types.

Tohru Nishimura
Nara Institute of Science and Technology