Windows Mobile 5 for Pocket PC was based on Windows CE 5 and contained numerous fixes and improvements over Pocket PC 2003 SE.
Pocket PCs running previous versions of the operating system generally stored user-installed applications and data in RAM, which meant that if the battery was depleted the device would lose all of its data. Windows Mobile 5.0 solved this problem by storing all user data in persistent (flash) memory, leaving the RAM to be used only for running applications, as it would be on a desktop computer. As a result, Windows Mobile 5.0 Pocket PCs generally had a greater amount of flash memory, and a smaller amount of RAM, compared to earlier devices
