What do you think will be the benefits of this new O.S. ?
The O.S. will not reserve anymore an ammount of battery space for the 72h of security time before next recarge, due to the Persistant storage, and more than this, the ram will not be continually powered to retain data...
Considering some other optimizations, what do you think that'll be the improvements?
20%... maybe 30%... or 40% or what else?
thx

The Axim X50 has 1100 Mah battery, so all in all, i would say a 30-40 percent increase in battery life. If you have a larger battery, such as a 2200 mah, then the percentile would be smaller. Either way, your gaining more battery life.

Out of interest where did you get those numbers from?

#1) what does the size of the battery have to do with % increase in battery life?!?

#2) You probably dont want to know where those numbers come from!!!

Why won't memory need to be continually powered with WM 2005. Although RAM isn't used for Storage memory anymore, it is still being used for Program memory, which I'm assuming holds the state of any apps that are currently opened. If I want to be able turn off the PDA (or have it automatically power off) and be able to return to where I was when I turn it back on, then I beleive the memory still has to be powered. And I don't believe it matters how much of the memory is actually being used - it all needs to be powered.

Anyway I may be wrong, but I'd be surprised (pleasantly, of course) if I saw a major increase in battery life with WM 2005.

Ken

I'm with Ken. We really don't know how it is all going to go down, but there will also be increased I/O overhead (moving things back and form between RAM and BIS) as well as the CPU running at max more often.

I'm guessing that the acutal gain in battery life will be minimal - but this is ONLY a guess (i.e., I have no real data).

Current PDA: Dell Axim X50v
Past PDAs: Palm IIIxe, Casio E125, Audiovox Maestro, Kyocera 7135

Would you believe that moving to PS can double your battery life and enable devices with significantly more storage than were previously possible?

Here's why. Remember that RAM requires power to keep its data. The amount of power needed is linear with the amount of RAM. That is to say, 64M of RAM needs twice as much power to keep it running as 32M does. 128M needs four times as much power as 32, etc. And this power drain is constant. The RAM is sucking your batteries dry while the device is in use and while it's suspended. It even continues to drain your batteries when they are "critically low" and the system won't let you turn it on. Also, people didn't buy 128M RAM devices for the program space. They bought them to store stuff in. And those devices had lousy battery lives as a result.

Flash ROM, on the other hand, burns pretty much the same amount of power regardless of how much you have. A 32M flash part burns about the same amount of power as a 128M flash part does. And a 1G flash part is pretty much the same as well. So, by moving to a system where I store my stuff in flash, not RAM, I can put more storage in without requiring a bigger battery to compensate.

But wait, there's more. Pre-Persistent Storage, Windows Mobile had what we called "the 72 hour rule." If you've ever seen a PocketPC run low on batteries, at some point it pops up a dialog that says something like, "You're running out of power, you should stop now." If you keep using it, it'll come back a little later with a more dire warning saying something to the effect of, "You'd better save your data now, because you're on the verge of losing it." Then, a bit after that it comes on and says, "That's it, I'm shutting you down." At that point, you can't use the device again until you plug it in. How much battery charge do you think you have then? 5% maybe?

Try half.

Yes, when we shut you down because your batteries were "critically low," they were still 1/4 to 1/2 full. Why? Because, if the batteries ever fully died, it would be catastrophic. You'd lose your data, and that's, in our opinion, one of the worst things that can happen. So we made a requirement and held our OEMs to it. The requirement was that, at the point where we decided the batteries were "critically low," they had to still have enough power to keep the RAM charged for 72 hours. The idea there was that you could discover that you were out of power on Friday on the way home and you'd still have your data on Monday when you got back to your charger.

A typical battery holds 1000mAh of charge. 128M of RAM takes about 500mAh to stay resident for 72 hours. 64M takes about 250. This is why you never saw a 256M WM 2003 device. It would have run for a minute then decided its batteries were critically low.

This is why switching to Persistent Storage can radically improve your battery life. With PS, we removed the 72 hour requirement. We'll let you run your batteries completely dry, because we know your data will still be safe. Right off the bat, that buys you a significant chuck of time. It also means that no one ever has to make a 128M RAM device again. They can fall back to 64M devices, which burn less power, and store the user data in tons and tons of flash. You'll definitely see 128M flash devices. And there's no barrier to keeping you from seeing 256M, 1G, etc devices. That couldn't have been done with RAM.

Downsides? Yes, nothing is free. Flash is much slower than RAM. Reading and writing large amounts of data will take longer on a PS device than it did on a RAM device. That initial sync that pulls down 400 contacts and 5000 emails will take longer. Some write operations will seem a bit more sluggish. But I believe you'll find that the upsides significantly outweigh the downsides.


as i read from http://blogs.msdn.com/windowsmobile/...14/438991.aspx

I understand that if you move to a device with all persistant storage you may get significant increases in battery life. I think Palm has done that recently on some of their devices.

But if you take today's devices such as the X50 and just uprade them to WM 2005, you're not really moving to persistent storage. You're just moving some things from RAM to persistent storage. You still have the same RAM that you need to keep completely powered if you want to retain your application state. So I don't see a gain in battery life there. Now the memory architecture does lessen the need for more RAM. So you can get by with a 64mb device rather than a 128mb device more easily and that could save battery.

I also understand the 72 hour thing. My Ipaq 2210 allowed you to change that so I would set it to 24 hours since I did an automatic backup every day. It gave me longer battery life but not dramatically longer. But again, with current devices, you still have the same amount of memory you need to continue powering when the battery gets too low. Now with WM 2005 they may have decided they don't need to protect the program memory (which, BTW, might hold that large TextMaker doc you've been working on but forgot to save). So they just run the battery down very low before shutting off and if you end up running the battery down completely, you'll only lose what you had in program memory. I'd be surprised if that's the approach they took, but I really don't know.

Ken

Thanks for the blog link...looks like a useful place to read from time to time.

-pedagogue

Actually, upgrading an X50v to WM5 will bring you persistent storage. That's what the built-in flash memory is for. You'll of course still have to have RAM, but you have to have RAM no matter what. A device can't run without RAM.

Thank you very much for the blog pointer and the post. That article caused me to have an aha moment regarding all of the PS in the x50v. It looks like WM5 will really improve the x50v.

jerry

Nobody said that with WM2005 PPCs will stop using RAM.
The article in the blog explain very well how the RAM and ROM will work under Magneto.

Well it will improve battery life, but at a cost of being a lot more sluggish. Maybe PIE will be better though.

IMO, wm5 will greatly improve it.
I guess RAM would only be used for programs. That's not a big deal tho, it's already like that in my x50v..

I hope there's a clear memory option when you shut down the axim, it'd like that!

Is it possible to remove the 72 hour rule in 2003se?