[jpstewart]

FWIW, I found a high resolution photo on-line of some 32MB O2 RAM modules. I was able to read the part numbers HM5216165TT10H and D4516161G5 off the chips. (Same stuff, two different manufacturers.) You can Google for that part number to find the datasheets for the chips and extrapolate some info from there. They are discontinued products, of course. 

If anyone has a higher-capacity O2 RAM module (or photo), find the part number on the chip, get the datasheet, and compare the two.

As weblacky observed, the modules have parity or ECC: there are 9 RAM chips per module.

I haven't been able to get a part number from the smaller (SPD?) chip in the middle of the RAM module.