Thanks for responding. If we are talking about desktops or laptops, then this patent would seem relevant:

US5787445: Operating system including improved file management for use in devices utilizing flash memory as main memory

It's the only patent listed that doesn't mention handheld devices, though it would seem to include them. I assume the operating system refers primarily (or exclusively?) to MicroOS. To what extent is MIcroOS used in flash-based devices?