I have recently acquired a NEC MobilePro 790 PocketPc from 2001.

The specifications says that the device has 48MB memory, including 32MB of RAM and 16MB of flash storage. It also has a ROM that stores the OS (I guess), that is Windows CE 3.0.

As it has 16MB of flash storage, you would think that the PocketPC user's information would be stored on them, but they actually doesn't seem to be. If I remove the battery, my account informations (Name, address...) and settings (Date, time, touchscreen calibration...) are reset and the PocketPC will run the configuration wizard on boot as if it was first time is was used.

I also found a setting in the configuration panel that allows to split the RAM between "Programs" and "Storage". By default, 16MB is allocated to each.

So my question is, are the NEC MobilePro's settings really stored in RAM, and does it really have any PSA (Persistent Storage Area)? Also, do most PocketPCs work the same way?

PS: I am sorry if PocketPCs don't fit in the RetroComputing Stack Exchange but I feel like they are obsolete and thus fit in retrocomputing.

2 Answers 2


The RAM is the means of (relatively) persistent storage. Even when the device is "turned off", the contents of RAM are maintained using battery power. Power to the RAM is provided by the main battery, and by a "backup battery" that's there specifically to keep your data safe when the main battery is dead, or while it's being removed. If the backup battery also dies, your data is gone. According to the manual, a fully-charged backup battery can hold the data in RAM for 7 days after the main battery is drained.

In general for a system like this, there are two keys to keeping your data safe:

  1. Charge it regularly. Just like a cell phone, if you use it regularly, then you may as well make a habit of charging it nightly, like a cell phone. NEC suggests charging it for 10 hours continuously after leaving it with the batteries completely drained; in normal use it shouldn't take as long.

  2. Sync it. The ActiveSync software is provided to sync data to a computer, and most things can be restored from the computer if they're lost, as long as they were synced recently. (Note: I have no idea how well this software works on modern machines).

Since this is a 15-year-old machine, an additional step, if you're up to it, is to disassemble it to find the backup battery, determine whether it holds a charge, and replace it if it doesn't. If you lose your data immediately after removing the main battery pack, the backup battery is suspect and might need replacement.

Reference: user manual.

  • There is a diagnostic of the backup battery in the control panel that says it's in "Good shape", and apparently the NEC MobilePro 790 is either new or was not used a lot as it seems in really good shape (The main battery is also diagnosed as in "Good shape" in the control panel). And so what you mean is that there isn't any real permanent storage like real flash memory? Sep 13, 2016 at 20:06
  • @user2109 the OS is stored on flash, and it's possible to copy apps there, but data stays in RAM. There is also a CF slot.
    – hobbs
    Sep 13, 2016 at 23:45
  • Isn't the OS stored in ROM (Read Only Memory)? If not, why is there a ROM module? Sep 14, 2016 at 8:13

Ah yes! The start of the "instant-on" revolution. According to this website, it has:

  • 16MB of internal ROM, with 14 MB available for storage; and
  • a CompactFlash slot that you can stick a 16 MB card into.

I'm trying to remember if that range had an emergency coin cell battery to keep data while you changed the batteries - I can't see any reference to that however. I think the LiIon battery was supposed to keep the data, and you were supposed to recharge it before it ran out.

  • The NEC MobilePro 790 seems to have a coin cell battery. There is diagnostic of the "well being" of the "Safety battery" in the control panel. Moreover I noticed one when I disassemblied mine to check how it was made inside. But still, the account and settings are reset when removing the battery even if the "Safety battery" is marked as "In good conditions" in the control panel. Sep 13, 2016 at 19:58

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