Main memory is organized into a storage heap and a dynamic heap, the former being the persistent store. The storage heap contains databases. These are not SQL/Oracle style databases, but rather a simple ordered collection of records. Each record has a header with some basic information, plus a handle that points indirectly to a chunk of memory. This means each record can have a different size, and you can resize a record to be bigger without shifting the later records. This database concept works well for storing PIM data such as addresses, events, and memos. With this approach, each application is responsible for presenting it's own record list, so there is no equivalent to the open dialog of Windows/Mac. The result is a simple device that's easy for people to understand.
Palm devices like the m500 have a file system on their expansion card, but the user isn't exposed to the entire complexity of it, but rather is presented in the Launcher with a flat list of all the applications on the card. -- Peter Epstein -- For information on using the Palm Developer Forums, or to unsubscribe, please see http://www.palmos.com/dev/tech/support/forums/
