Hi A V:

One of My computers is a 486-DX266 Circa 1995. it has slots for 30 Pin
simms and 72 Pin Simms. Like yours I can set it to run either parity or
non parity. My original 4 MB Simms came with 12 chips on them. There was
six chips on each side in groups of 3 each.
I learned, by pleading and begging, that each group of three consisted
of 1 MB of Ram plus a parity check chip. I will bet that yours are the
same.

I will wager that the 4 MB Simm  that you have with 16 chips are counted
in groups of fours. That is in each group of 4 there are 3 ram chips of
250K each plus one parity chip.

When buying replacement Simms the number of chips on each simm is not
important as long as they add up to the required amount stated For
Example: 1X36 = 4 MB
         2X36 = 8MB
         4X36 = 16 MB

The above example is for parity chips only.

How many Simms slots do you have? Do you also have slots for 30 Pin
chips? You should check your manual to see what combination of chips can
be installed. If you only have the two 72 Pin Simm slots, you will have
to replace both slots with the exact same amount of Ram. that is if you
put 8 MB in one slot, you must put eight MB in the other slot. If you
have 30 Pin slots in addition to the 72Pin,let me know and I can tell
you what I do.

I hope that this information is of some value to you. Perhaps someone
else on the list will either confirm or correct my information. I only
work on my computers. Some of the persons on this list are
professionals.
TurtleAL



A V wrote:
> i have a 486 that was pieced together from spare parts lying around.  it
> was given to me with no documentation.  running win3.1, and blah blah old
> stuff.
> 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.  i wish to add more, possibly
> 16 meg, but how do i tell?  so far, since it's a 486 i'm assuming parity
> because of the age.  but 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?
>
> installation will be fine and easy (so he says) and everything else fine
> just how do i tell???
>
> Thank you in advance....very much
> David A. Abbe
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