Microsoft Explains the Advantages of Persistent Storage

Ed Hardy · 07-18-2005, 10:47 AM

A discussion on the advantages of Persistent Storage has been added to the Windows Mobile Team Blog. The advantages include a greatly increased battery life and the ability for future Pocket PC to have far more built-in storage.

Read more at http://www.brighthand.com/article/Pe...Thing?site=PPC

rsc1000 · 07-18-2005, 12:03 PM

Q: is more power required to read from and write to flash ROM than RAM?

Timothy Rapson · 07-18-2005, 12:31 PM

Right now I only run into one memory problem on my Zire. I have a map of the world in Adobe format that I can't use in Adobe. Why?

Well, with 14 MB free of 28-32 MB available, I get an Adobe message that says it can't load this 2-3 MB file (I am guessing that it is VERY compressed, but how in the world can this be? Anyway it is.) says I don't have enough RAM to run it full sized. I have freed a lot of memory and seen it full sized once, but it still didn't zoom in to the size I have it available on my desktop, which is huge, but exactly what I want in a world map. Alas.

I hope WM 2k5 fixes this, because having it all PLUS this on an Axim X50v with the graphics chip making it scale as smooth and fast as on my desktop, while living twice as long per charge without fear of losing my contents....well that makes my heart go all pitter patter.

Or maybe it will make the whole OS go all twitchy like some of the older PPCs versions and I will find out that a reboot takes forever now like on the T5 that uses Palms version of this persistent memory trick.

....Eagerly awaiting that first review of the X60v right here.

Heda · 07-18-2005, 01:46 PM

while technically what MS says might be true about saving battery, they forget to tell u if u do turn the device completely off u are going to have to wait for it to bootup everytime u turn it on (should take about the same amount of time as a soft reset does now). the only reason PPC's have instant-on right now is because the "current session" is saved into RAM, which means PPC's are only in stand-by not turned off. which tells me that even if u want your WM 5 handheld to be instant-on your going to have to put it in stand-by also, which will drain battery, which means we're back to square 1. the main difference being now though, if your devices runs out of juice everything is still safely in ROM.

Timothy Rapson · 07-18-2005, 01:55 PM

By the way, Casio and Sharp have offered numerous models that used 100% flash memory. They had great battery life. I was told way back then that even though Flash was slower than RAM, at the speeds of those days (A 66MZ processor was overkill in mono PDA) it didn't matter because even slower flash memory was faster than the processor could read/write to it anyway.

I expect this fits very well with Samsung's huge leaps in speed, cost, and capacity of flash memory. Intel chips for sure, and I think just about all ARM chips are now shipping with flash memory right on the CPU.

I am seeing 1 GIG SD cards (flash memory, that I am assuming is just the same chip as the makers put in PDAs) go for just $50 a lot lately. NewEgg was offering a 66X accelerated chip today for $57 and you didn't even have to mess with a rebate. I've seen 512 cars for just $19!. If they could spend that same amount and put that flash memory in an Axim X60v adding only $20 to the price, I might never have to buy a memory card for it. Or I could use a 512 card just for mobile backups. I already have two 256s, one 512, and one 1 GIG card. They just keep getting bigger and cheaper. Wish they didn't always seem to make me mess with the rebate forms though.

Wonder if I would have the guts to let that battery run down to completely empty regularly though. Too dicey.

Ed Hardy · 07-18-2005, 03:18 PM

Quote:

Originally posted by Heda
while technically what MS says might be true about saving battery, they forget to tell u if u do turn the device completely off u are going to have to wait for it to bootup everytime u turn it on

I think you misunderstand what Microsoft is doing. While applications and files will be stored in Flash ROM, the device's RAM will be used to hold currently running applications.

This means that every time you turn a Pocket PC on, it will still be in the state that it was when you last turned it off. You won't be booting it up from a "cold" state.

Only in the rare situation when you let the handheld's battery completely run dry will it have to boot up.

Effectively, users will hardly be able to tell a difference between the way current Pocket PCs work and the way they'll work under Persistent Storage... unless they let their battery run out. Then they'll be happy to discover that they haven't lost everything stored on the device.

dennarda · 07-18-2005, 03:49 PM

Correct me if I am wrong, but this is nothing new. Isn't this equivalent to the features available on the Tungsten T5 and a variety of other PDA's that have been available for a while? I agree it is a great feature, but it seems a bit late to explain how wonderful it is. It's like tell us about the advantages of color screens

Heda · 07-18-2005, 03:54 PM

read my post more carefully Ed. i didnt misunderstand anything MS said. keep in mind when i say shutting off and stand-by i mean it (i dont say shutting off when reffering to current PPC's because they dont technically). everything u said only restated what i already said. i will rebreak it down again though i suppose.

current PPC's do NOT shut off, they just stand-by

current PPC's are instant-on because they save the "current session" into RAM, which requires them to be in stand-by, which requires draining juice.

if WM 5 PPC's are instant-on that means they will ALSO be in stand-by, which means they will also drain juice.

the difference between WM 5 & current PPC's if u run out of juice ur data will be safely stored in ROM.

if u truely turn off a WM 5 device it WILL have to boot up which will take about as long as a soft reset does on current PPC's.

keep in mind this new storage technique will come at a cost, programs will start up slower because the programs are going to be pulled from the much slower ROM, where as before they were pulled from the much faster RAM.

surur · 07-18-2005, 04:25 PM

The difference is that you wont necessarily need 128Mb now, whereas before (I feel) it was essential. This reduces your battery usage as you only have 1/2 the amount of ram to keep alive (64 vs 128).

The second advantage is being able to go all the way to 0%, vs apparently 50%, greatly increasing available battery life.

Surur

ctitanic · 07-18-2005, 04:38 PM

what I don't understand is what he is saying about the battery level. is this means that when the battery level says that the battery is at 5%, lets say, and your PPC goes off no letting you to turn it on again, in reallity the battery level is wrong and the real power % is may be 35 % or more?

is that what he is saying?