On devices with flash ROM (as opposed to mask ROM), you can write to the
flash memory using suitable tools. This memory, as well as the volatile RAM,
are attached to the processor and accessed directly in the usual way. Of
course, the flash ROM has a different range of addresses than the volatile
RAM. The operating system and some of the applications normally reside in
flash ROM, while applications the user installs reside in RAM. When the
device is hard reset, no copying of applications takes place. Applications
such as Datebook that reside in flash ROM stay there. They are never copied
into RAM, but are run directly from ROM. The data manager supports accessing
databases in both RAM and ROM. Since applications are stored in resource
databases on the device, that means applications can be stored in ROM, and
can be accessed via the data manager in the same way as applications in RAM.
I've heard that applications developed to run from RAM may not work when
placed in flash ROM. I don't know whether most applications would work from
ROM or not, but I suspect so. The Launcher won't let the user delete
applications from ROM. If the user wants to delete an application from flash
ROM, he needs to re-flash his device with a different ROM. Palm users don't
normally have access to any tools for flashing their ROMs other than
specific tools for upgrading to a newer OS version. If you want to see how a
new ROM works without taking the time to flash your device, try running it
in POSER.
--
Peter Epstein
--
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