I think only the latest Treo had 128MB - the last PDA (Lifedrive) had 64MB, the TX 32MB.

(One should remember though that there wasn't mass storage+RAM as we typically think of it - the memory of the Palm devices was storage and active memory in one. Battery-backup'ed until the very latest models. There wasn't a filesystem as such. So all this memory should be thought of as memory for applications, nor like storage in an Android device.)

Do you recall how the memory worked for the expanded storage on Palm OS devices that supported it? I had a Sony Clie TG-50, which supported Sony's proprietary pro duo memory cards, allowing me to expand the storage with a 2gb card, from the original 11mg of usable shared memory. I also recall that there was some sort of directory app, which allowed for the observing of files on either the device or the card. I'm curious how this would have worked.

I should check this - I still have some SD cards which I used with my T3 (I had two Tungsten T3 PDAs actually). But I think they were simply FAT-accessed, i.e. different from the internal storage. I'm unable to verify that at the moment. It's correct that there was an entry in the system menu or some such to look at the card. Again I can't check this - battery is out on both my T3 devices, and charging got more and more tricky over the years (the Palm socket was a very weak point)

.. should not be thought of.. was what I meant to write. The memory is neither app memory nor storage, but both at once. The once-Windows based PDAs also used a combined memory setup, but there one section of the memory was for running apps, the rest for storage, i.e. different from PalmOS.