PS/2 model 35 ram compatibility ?

[whaka]

Hello,

Is the model 35 using a proprietary pinout for ram ?
I know it require parity, but it seems to be not enough. I tried a pair of 8MB (HP branded) 18 chips 2Mx36 organisation, as the ibm one. but nope... they doesn't work at all.
I get a real ram error code, like when there's no ram in any slots.

Thanks.

 

[WBST]

IBM PS/2 presence detection pre-dates the so-called "industry standard" variety:
https://eprm.ardent-tool.com/eprm/f232.htm

 

[whaka]

many thanks.

damn... i had no clue about that.
this very probabely explain why the HP sticks have 4 empty resistors pads... i'll check if they're connected to the identifiaction bit.
and if it is, then i'll try to mod them.

thanks again.

 

[whaka]

and of course they are
just have to directly solder bridge (they use 0ohm resistors on ibm sticks) the pads which connect pin 69 to ground, to identify as 8MB 70ns.
i can't test for now as i work on the psu, but i think it'll be fine now.

thanks again for the tip.

 

[whaka]

tested, approved