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Thema: Peter! 8 MB PD for PS/2 Note N51sx Von: Jim Shorney Datum: Mon, 12 Jul 1999 20:53:11 -0500 Paging Mr. Wendt! Thank you again for your wonderful page on IBM presence detection for memory modules. I acquired a new toy last night, an 8551 N51sx notebook (traded one of my model 80's for it). I've been playing with it and decided it was badly in need of more RAM, so I went to your page and did some studying. After a few minutes of tinkering, I was able to determine that the PD code for an 8 MB Parity SIMM in this beast matches the configuration for 8 MB non-parity on your page (which is marked "reserved" in the parity RAM chart). That is, pin 70 shorted, all others open. I also determined that the machine does definitly require parity memory, but the industry standard 8 MB parity module works fine and passes diags. Had to trim that white nub on the socket down for it to seat properly, of course. The N51sx also seems to be an IML machine, FWIW. Now if I can just find a bigger SCSI drive for it... Has anyone had any luck using IBM OEM drives from Apple Powerbooks in x86 machines? I have one here, but have never gotten it to work properly in anything but a Powerbook, and it does seem to have an Apple ROM in it. Jim -- Jim Shorney jshorney@inebraska.com Lincoln, NE, USA http://incolor.inetnebr.com/jshorney
I try to bring a diagram of the module, how it probably looked like:
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8MB / 70ns - Before conversion:
+------------------------------------------------------------------------+
| ################ ################ ################ ################ |
| ##### Bank ##### ##### Bank ##### ##### Bank ##### ##### Bank ##### |
| ####### 1 ###### ####### 2 ###### ####### 3 ###### ####### 4 ###### |
| ################ ################ ################ ################ |
+-+ ooxo |
|1 ||||||||||||||||||||||||||||| __ |||||||||||||||||||||||||||| 72 |
+--------------------------------+ +----------------------------------+
^--Round notch about 2mm deep
||||
o= open connection 67-++++-70
x= zero ohm resistor ||
68--++--69
8MB / 80ns (N51) - After conversion:
+------------------------------------------------------------------------+
| ################ ################ ################ ################ |
| ##### Bank ##### ##### Bank ##### ##### Bank ##### ##### Bank ##### |
| ####### 1 ###### ####### 2 ###### ####### 3 ###### ####### 4 ###### |
| ################ ################ ################ ################ |
+-+ ooox |
|1 ||||||||||||||||||||||||||||| __ |||||||||||||||||||||||||||| 72 |
+--------------------------------+ +----------------------------------+
^--Round notch about 2mm deep
o= open connection
x= zero ohm resistor
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© 1999 by Peter H. Wendt / pw-software production