Why Some Models Can Get Windows Mobile 5.0 Upgrades... and Some Can't

When Windows Mobile 5.0 was unveiled earlier this week, I don't think enough attention was paid to one of its better features: persistent memory storage.

With this, Pocket PCs will retain all their data, even when the battery is completely depleted.

Anyone who has ever accidentally let their handheld run out of power -- which means everything on it was erased -- can appreciate the advantages of this.

To fix this serious limitation, Microsoft has completely revamped the way Pocket PCs handle their memory.

The Current System

Handhelds have two different types of memory: RAM and ROM. With the current Windows Mobile handhelds, RAM is used both to store applications and files, and to hold applications while they are actually running. ROM is where a backup version of the operating system is held, plus some models give users some space in ROM for additional storage.

In order for RAM to keeping holding everything that is stored in it, power must be supplied to it constantly. Even when your handheld is off, it keeps supplying power to RAM.

Incidentally, this is why handhelds don't have 512 MB of RAM or more. This would drain the battery much too quickly. You'd run out of power every night, even if you never used your device at all.

ROM, on the other hand, continues to hold its contents even without power. If you let your handheld's battery run out and lose everything in RAM, any files stored in ROM are still there.

The New System

Persistent memory Storage means that future handhelds will use RAM and ROM very differently.

Pocket PCs running Windows Mobile 5.0 will use RAM only for currently running applications, and nothing else.

All storage of applications and files will be done in ROM.

I think you can see the advantages of this. If your device runs out of power, you don't lose your applications and files, or the contents of your address book and calendar.

Also, with RAM no longer being used for storage, your current device will have a lot more space for running applications. It's going to be like getting a big RAM upgrade.

I've read some doomsayers predicting that constantly having to pull things out of ROM will really slow future Pocket PCs down. I'd like to point out that current Windows Mobile smartphones already handle RAM and ROM in this way, and they aren't unusably slow.

The Downside

At this point, I'm sure some of you are asking, "What does this have to do with my iPAQ rx3415 not getting an OS upgrade?"

For all of persistent memory storage's advantages, is does have one drawback. It requires Windows Mobile 5.0 handhelds to have lots of ROM space. In addition to giving you enough room for all your applications and files, there still needs to be a backup copy of the operating system in there.

This isn't any big deal with future models, or current ones that offer plenty of extra ROM space, like the Axim X50v.

But many recent Pocket PCs just don't have enough ROM space to let persistent memory Storage work. And this means they can't be upgraded to Windows Mobile 5.0.

Well, probably some of them could be, but would you really want a handheld with about 4 MB of internal storage?

This doesn't mean that you should get mad at HP or the other licensees for making handhelds without 128 MB of ROM.

Developing a handheld takes a long time. Work on a device that came out last summer probably started in mid 2003. That's a little early to know that it needs something for an operating system upgrade that won't be available until mid 2005.

Update: I didn't mean to imply that insufficient ROM space is the only reason why some models won't get upgraded. There are certainly some Pocket PCs that physically could handle the upgrade but won't get it.

This is happening for a variety of reasons. Some are obvious. The Axim 30 series isn't getting the upgrade because Dell is about to discontinue these models. No Toshiba device are getting the upgrade because this company has pretty much dropped out of the handheld market.

However, for some Pocket PCs the situation is less clear. In my opinion, the minimum amount of ROM in a Windows Mobile 5.0 device ought to be 128 MB, and a lot of the devices getting upgrades have this. However, there are some iPAQs with 64 MB of ROM that are getting an upgrade, and some that aren't. There are even recent iPAQs with more that 64 MB of ROM space that aren't getting it.

People have come up with various explanations for this. I noticed only after writing this editorial that none of HP's models targeted at the consumer market -- as opposed to the business market -- are getting upgrades.

An article on Dave's iPAQ points out that the only models getting the upgrade use an Intel PXA270 processor.

Anyway, to sum up, while a lack of ROM space certainly prevents some models from being upgraded to Windows Mobile 5.0, it clearly isn't the only reason.