Your system stands a very good chance of supporting parity ram as
non-parity when the BOIS selection is disabled.  I frequently installed
30 pin parity ram mixed with 72 pin non-parity in 486's and had no
problems when I disabled the BIOS parrity selection.  I don't know what
you mean by staggered.  Do you have 30 pin simm slots?  Are they
empty?  If you only have 72 pin slots you can probably install any
combination of single sided and double sided simms.  Singles are
usually 4 and 16, double 8 and 32. If you have 30 pin simms you
probably have limited options with 8 and 32 meg simms since the
bank numbers between the simm slots overlap.  This usually means
a jumper has to be moved to assign bank zero to 30 pin or 72 pin ram,
since a double sided 72 pin simm occupy one slot but uses to banks,
( 0 and 1) and 4 30 pin simms make up on bank (usually).

So the short answer turns out to be buy non-parity 16 meg and put it in a
currently occupied slot, removing one of the installed four meg simms.
The long answer is there really are not that many permutations to choose
from and even without the manual you should be able by trial and error to
find a way to install a 16 meg non-parity simm and get all the ram
recognized.
tom turak
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David Abbe wrote:
> i have a 486 that was pieced together from spare parts lying around.  it
> was given to me with no documentation.
> It initially had 4 meg of memory, then another 4 meg was added.  The
> chips are different looking, one is staggered one is not.  I still am
> unsure how to tell if it is parity or non.  Looking on the chips themselves
> i see that it is 72 pin, and on one of them there are 16 (chips) and the other 12.
> I had thought that parity would have an odd number of chips on the memory
> module, so now that makes these non-parity, my bios has a selection for
> parity error checking, though it is disabled....so what do you all think?
>
> David A. Abbe
> [log in to unmask]