> Date: Sun, 28 Feb 1999 08:35:09 +0100
> From: Bernie <[EMAIL PROTECTED]>
> Subject: Re: win95 whith 486 dx250 MHZ whith 4 MB ram
>> The new 4 meg sims have three chips on them whith all the same part
>> number, these are the sims that don't work.
>> The 4 MB sims that do work have two chips whith the same part number and
>> one chip whith a different part number on it.
>> Well I ran on long enough for now, I think.
Generally SIMMs with an odd number of chips are parity and those with an
even number are non-parity and usually cannot be mixed. Some
motherboards demand parity; some do not. Also IBM motherboards of the
PS2 vintage especially seemed to demand IBM SIMMs. If these are 30 pin
and not 72 (72 have a notch approximately in the middle, 30 has no notch
and are somewhat shorter) chances are they are not EDO. Some mid-90's
motherboards had slots for both sizes; so you could mix them. Otherwise
you could not. Some 72 pin motherboards allow non-parity and some
parity MB allow you to set the CMOS to skip parity check, allowing the
use of non-parity SIMMs. Also all SIMMs come in a variety of speeds,
such as 60, 70, and 80 nannoseconds, usually the slowest sets the pace,
if mixed which is not an optimum situation either.
Generally it is not a good idea to mix different kinds of SIMMs or
different speeds, but sometimes you can fudge it. The box that I am
writing this on has mixed 30 pin parity and 72 pin non-parity SIMMs, but
I get an occational memory address fault; such as in Tom's Root Boot
Linux, which will not load on this box, but will on another with uniform
SIMMs.
One other thing, it is my impression that 30 pin SIMMS have to be loaded
in sets: 4 for parity and 2 for non-parity, but I may have the numbers
wrong, definitely in pairs. It's been years since I built this box, and
I am about ready to retire it. It seems that I needed a set of 4 1-MEG
parity SIMMs to get started then, but I was very green then and not much
better now; so that may be incorrect.
Memory is so cheap these days that it is most certainly cheaper to buy a
properly matched set than to spend the time to match a group of orphan
SIMMs, unless you have both the expertise and a lot of spare time (and a
little luck).
This is all about PC SIMMs, I have no idea what MAC uses.
End
Peace
Dale Hoogeveen Email: [EMAIL PROTECTED]
Home site: http://www.net-info.com/~dutch
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