These SIMM have IBM made chips in group of 9 chips of 4 bits each all identical to make parity of 36 bits wide. No matter what I set the sense detect pins correctly (Industry or IBM) I kept getting error right away during memory test POST on this compaq Deskpro 4/33i. Even set to 4MB 80ns with these IBM sticks still produces error. Exchange them all out for another correctly designed SIMMs worked.

When I exchanged for any SIMMs they works listed:

8 x 4MB x 4 bits with 4 x 4mb 1bit
8 x 4MB x 4 bits with single 4MB x 4 bits of the quad CAS 24 pin IC
2x 4mb x 16bits with 4 x 4mb 1 bits
2x 4mb x 16bits with single 4mb x 4bits of the quad CAS 24 pin IC
4x 4MB x 8 bits with single 4mb 4 bit quad CAS IC 24 pin IC
4x 4mb x 8 bits with 4x 4mb x 1 bit.

parity 72 pins modules requires 4 cas lines to work right especially for the four bit parity chips. that odd IBM made 4mb of 9 chips all same of 4 bits each does not work correctly. I was not happy that I have small collection of these I can not use.

This beyonds me how did IBM managed to able to use these in their IBM yet other SIMMs above will also work in theirs as well?!

Cheers,