SIMM Identification 

This file describes the presence detect system for 72-pin SIMMS. The 
information was taken from Document 16026 on the IBM PS Help Center 
Automated Fax System, 800-IBM-3395.

The presence detect pins, 67-70, tell the system the size and speed of 
the SIMM. Using good ESD practices and a digital volt/ohm meeter measure 
the resistance between pins 67-70 and 72.

The pins are numbered sequentially, starting from the notched end, i.e., 
pin 72 is the pin closest to the un-notched end of the SIMM.

Use caution to not put the meter leads on pins other than those used for 
presence detect. Depending on the voltage used by the DVM, damage to the 
SIMM could occur.

"I" indicates infinite resistance to pin 72.
"G" indicates <10 ohms to pin 72.

pin	pin	pin	pin	size	speed		notes
70	69	68	67	

I	I	I	I				not a valid SIMM
I	I	I	G	1 MB	120 ns
I	I	G	I	2 MB	120 ns
I	I	G	G	2 MB	 70 ns
I	G	I	I	8 MB	 80 ns
I	G	I	G      16 MB     70 ns
I	G	G	I	2 MB	 80 ns
I	G	G	G	8 MB	 70 ns
G	I	I	I				reserved
G	I	I	G	1 MB	 85 ns
G	I	G	I	2 MB	 85 ns
G	I	G	G	4 MB	 70 ns
G	G	I	I				reserved
G	G	I	G	1 MB	100 ns
G	G	G	I	2 MB	100 ns
G	G	G	G	4 MB	 80 ns