At 12:40 PM 2/1/00 -0800, Aaron J. Grier wrote:
>On Tue, Feb 01, 2000 at 10:22:55AM -0500, nm 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.
>
>Some of us have access to surface-mount (dis-)assembly equipment -- is
>this documented anywhere?

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.

At one end of the simm there are two rows of four solder pads.  One
row is connected to Vss (GND) and the other is connected to pins
67 (PRD1), 68 (PRD2), 69 (PRD3), 70 (PRD4).

If you bridge a pair of pads with a small resistor or a drop of
solder you ground that particular bit.

PRD1	PRD2	mem. size
---------------------------------------------
GND	GND	4 or 64 Mbyte
Open	GND	2 or 32 Mbyte
GND	Open	1 or 16 Mbyte
Open	Open	8 Mbyte

PRD3	PRD4	access time
-------------------------------------------------
GND	GND	50 or 100 nsec
Open	GND	80 nsec
GND	Open	70 nsec
Open	Open	60 nsec

He goes on to say that if the pads are not present, you can connect
a particular PRD pin to pin 72 with a small piece of wire to achieve
the same goal.

Big thanks to Dolf de Waal.

Nick Maniscalco