WinCE

At the Santa Cruz Flea Market I got, among other things, a Magellan Maestro 4050. I already have a slightly later unit, but this one has bluetooth. They run WinCE 5 which means most relevantly that they have persistent storage. WinCE 4 and earlier devices almost uniformly have only volatile memory, so when your battery runs out, your device resets itself to its factory settings. This was likely the best design decision Microsoft could have made, because WinCE 4 was an unreliable pile of debris that would corrupt its own installation at the slightest opportunity.