Stupid PDA "WHY" Question

diesel · 02-25-03, 01:34 PM

This might be a stupid question but out of curiosity why were PDA's designed in such a way that when your batteries completely die or you hard reset, all programs and data are lost and everything is reset back to its original state? Why is it that when you save something to the PDA's memory, that it's not truly saved like on a computer hard drive.

On a pda, if there's no power left in the device, all data is lost. On a regular computer that is not the case. What was the reason for this as far as PDA's are concerned?

Thanks.

Curious Eric

02-25-03, 01:39 PM

It has to do with the type of memory used. Some memory doesn't need power. I'm sure the reason is due to cost.

Cesio · 02-25-03, 01:57 PM

It isn't a stupid question but I don't understand it? Sorry!

If you do something on your PDA and save it, it's saved isn't it? Isn't that why there's a backup battery?

"Why is it that when you save something to the PDA's memory, that it's not truly saved like on a computer hard drive."

Eh? If you type something in Word (when Word isn't set to backup every x number of minutes) and turned a computer off, you'd lose that too.

Sorry if I'm replying to a point to you didnt' make! ;)

rcase13 · 02-25-03, 01:58 PM

I would think the main reason would be that regular harddrives require huge amounts of power to run. Where as CF or SD require very little. Even the IBM Micro drive requires huge amounts of power when compared to regular CF and SD memory.

Basically I think it's power related.

My .02

Rodney

Mike C · 02-25-03, 02:08 PM

... and it works fine, as long as the backup battery is good.

People have had trouble with the backup battery not making contact, or otherwise not doing it's job, so it would be prudent to make a good backup to the PC, and test your reserve power by removing the main battery. It should just go into suspend, with no loss of data.

IronMonkeyGF · 02-25-03, 02:26 PM

The Axim probably uses Dynamic RAM because it takes up less space since there is not as much circuitry as in static RAM. The dynamic RAM requires a resfresh to keep the capacitors charged since they lose charge over time, so if there is no power to refresh the capacitors, the data is lost. I only know this because I'm studying for my Computer Architecture final tomorrow, well....I'm taking a break right now. Wish me luck. ;)

numsquat · 02-26-03, 10:42 AM

It's not different than using RAM on your computer. If your computer locks ups using Word or such and you reset, you loose it. Same on a laptop if the battery goes dead.

Get a mem card. Funny how people will complain about buying a mem card for a PDA but won't wouldn't buy a computer w/o a hard drive. Outside of WMA's, 90-95% of my programs and stuff are either in ROM or on the mem card and I back up my RAM twice a day to the mem card. Haven't had a problem getting back to "normal" quickly and easily doing it this way. Sometimes programs take a second or two longer to load from the mem card but the safety of not loosing stuff is worth it.

JakeRich · 02-26-03, 11:02 AM

The technology is such that RAM, the volatile kind that goes away when power fails, is faster and consumes less power to read/write. The downside is that it has to be refreshed frequently to keep it working. I think in the normal operation of the Axim it's refreshed something on the order of once every 8 clock cycles. If that refreshment does not occur, the charge starts to die and data is lost.

The NON-volatile memory, ROM, CF/SD cards, etc. is much slower to read and write and consumes more power to do that read and write. The upside is that once written, it survives power failure and doesn't need to be refreshed.

So, basically, even when you "save" to the main memory, it's in a volatile media unless you do something to move it to non-volatile memory. That "something" is called backup.