[Upgrading, Modifying and Unlocking] cavyman:
Not quite right, atompson. There are ultimately two types of memory: RAM and ROM. ROM is much slower than RAM, but does not have to be powered to retain its data (non-volatile memory). RAM, on the other hand, is typically far faster than ROM, but it loses its data whenever it loses its power (volatile memory).

I'm not familiar with the hardware of the entire Axim family, but I know that X50(v)s and X51(v)s have both types of memory. The physical type of ROM is different between the X50 series and the X51 series. It is that physical difference in the ROM that makes the real difference between the performance of WM5/WM6 on the X50(v) as opposed to the better performance on the X51(v). However, as far as I know, the physical type (and amount) of RAM is still the same between the two devices.

When looking at the specs for an Axim, you typically see details for the Storage Memory and then RAM. Storage Memory is actually a more fancy name for ROM. The ROM of your device, believe it or not, is what holds the actual "ROM" image that we like to call Windows Mobile <name your version> :p. That is how your files in Storage Memory persist even after your unit is powered off or after your battery dies. Everything in your RAM, however, disappears anytime the power is turned off in any way. (There is also the case of "standby" which basically turns your device off, but still keeps power going to the RAM so data is not lost)

The main difference between WM5/WM6 and WM2003 (and older versions), as far as storage/memory is concerned, is that WM5/WM6 use a newer concept referred to as Persistent Storage. In WM2003, you could install programs into RAM and when you would press the power button on your Axim, you would enter standby mode. So your Axim never really powered off completely. There was always some power going to your RAM so it didn't lose its data. However, if your main battery died and you didn't replace it with another battery (or begin charging your Axim), your Axim's internal backup battery would continue to power the RAM for some time until you would hopefully get your device powered again somehow. But, if you didn't get power to your device before the backup battery died, there was nothing left to power the RAM and it would lose its data. If any programs/files were stored in the RAM, they were gone. Plain and simple.

The concept behind WM5/WM6 is that MS removed the ability to save programs to RAM and forced all user programs to be stored to the BIS (Built-in-storage, aka ROM) so that even if your Axim ceased to receive power, it would still retain its data since ROM is non-volatile. However, this change is what caused so much trouble in the WM5 A01 and A02 ROMs for X50(v) users. The physical makeup of the ROM in an X50(v) worked just fine for WM2003, but it was not designed for a lot of activity (file system access) like the faster type of ROM in the X51(v) allows. There are some really detailed reasons for why this is the case in the different types of ROM, but it is more than I really need to get into here.

If you want all the details, there is an excellent Microsoft Blog that goes into all the physical details (NAND vs. NOR) and gets into the concepts of XIP (execute-in-place) which works with some types of memory and not others. I can't find the link I once had, but if you Google it, it shouldn't be too difficult to find. I'm sure there are some other really great resources out there if anyone wants to find out more.

Hope this helps somebody out! :cool: