I'm a bit disappointed that this discussion thread has mostly been about nostalgia (which is great) and not the technical details TFA brings up. Really curious about the "everything is a database" concept and how it contrasts with other operating systems. Based on the article it sounds like the choice to design Palm OS like that was because of "strongly influenced by the classic Mac OS," and for "computing memory consumption"?
First, apps had no filesystem available, only a database which they could use as a datastore. It was not a particularly powerful or fancy database, everything had to be done via the C++ API rather than a query language IIRC. But it simplified app development quite a bit and made the apps smaller and more robust.
Second, there was a set of common tables available to all apps that provided the basic PIM data, including addresses, calendar, todo, email and notes. This meant that third party apps could safely interoperate with this data alongside the builtin apps and extend functionality.
