> From port-alpha-owner-clowenst=ucsd.edu@netbsd.org Sat Feb  5 10:18 PST 2000
> Date: Sat, 05 Feb 2000 13:16:43 -0500
> From: nm <nmanisca@vt.edu>
> Subject: Re: 3000/300 : SCSI speed & RAM questions
> X-Sender: nmanisca@mail.vt.edu
> To: Brook Milligan <brook@biology.nmsu.edu>
> Cc: port-alpha@netbsd.org
> 
> At 09:25 PM 2/4/00 -0700, Brook Milligan wrote:
> >   >> I have heard that it is possible to use drops of solder to convert a
> >   >> non-recognized 32MB simms to a recognized 32MB simms but it is not
> >   >> trivial.
> >
> >   Dolf de Waal seems to be very knowledgable in this area.  He is
> >   the person who informed me of the presence detection bits.
> >
> >   The following information is almost directly from Dolf de Waal.
> >
> >   There are four presence detection bits on ps/2 simms.  Two of
> >   the bits indicate the access time.  The other two indicate
> >   the memory size.
> >
> >Are there any "official" documents that describe this setup?  I
> >presume there is no requirement for SIMM vendors to sell products with
> >the correct jumpering of these pads?
> 
> I really have no idea if this is a requirement for simms or not.  I
> have never come across any technical docs related to something like
> this.  Sorry.

Time for some reality check, or net search, or both.  There is a JEDEC
standard for SIMM memory, it is probably the one named JESD21-C.  Since
it costs $150 to buy, I have not looked at it.  This information comes
from the JEDEC web site.
	http://www.jedec.org

Documentation on various 72-pin SIMMs, with full pinout specifications,
including presence detect bits can be found at
	http://www.micron.com/mti/msp/html/obsoleteds.html#DRAM SIMM

Another tabulation of SIMM pinouts can be seen at
	http://www.computerbooksonline.com/repair/chapter51.htm

This took about 10 minutes of Web search and browsing, and sure beats three
rounds of speculation.

    carl

        carl lowenstein         marine physical lab     u.c. san diego
        {decvax|ucbvax} !ucsd!mpl!cdl                 cdl@mpl.ucsd.edu
                                                  clowenstein@ucsd.edu