Re: how much space does Win Mobile 2003 take?

From: ACE!!! (ace_rules_bbs_at_hotmail.com)
Date: 11/24/04 

Date: Wed, 24 Nov 2004 01:32:31 -0800

Hello Andrea,

You are correct, regular desktop pc's running Microsoft Windows indeed
have an identically set up registry to store vital configuration data.
However here comes the big difference: A desktop has a harddisk to
permanently store data, whereas a PPC does not. that was the short
explanation ;) :)

The long explanation:

Typical desktop: uses a harddisk to store data, and RAM for executing
programs and processes. during shutdown, everything stored in RAM that
has to be stored again is written back to the harddisk. Able to retain
all settings after being shut down including the time, regional settings
programs, documents and all other data for years to come.

Typical PPC: uses ROM to store the OS, and RAM to load parts of the OS,
execute the OS and programs, but also to store user data. This is divided
50/50 on the first boot, and is automatically managed by the OS to keep
a balance between available RAM for running programs and the ability to
store your documents and other stuff. A PPC does not 'shut down', it goes
into a 'Hibernate' mode where the processor goes idle and the screen off,
but RAM and the internal clock remain active.
Here is where a PPC differs from a desktop pc, the RAM part functions as
both RAM and harddisk, with one exception: the RAM part needs a constant
power feed to be able to retain data as opposed to a harddisk. Vital parts
of the Windows Mobile operating system are loaded into RAM when the PPC
is initialised for the first time, to be executed in RAM from that point
on. One of these vital parts includes the Windows Mobile registry.
To protect the device from OS corruption and provide you with an easy
way to restore the device to factory settings, the ROM part of your PPC is
set to be read only, and therefore the registry remains in RAM.
(Even though the ROM is flashable, but this is only for updates/upgrades
of the internal OS and third party drivers/firmware.)
Now, when your PPC completely loses power.. the RAM part can no longer
store your data and settings, and the device performs a 'hard reset'.
The RAM is now empty and when you turn the PPC back on after recharging
it, it will once again put you through the first initialisation process
with the touch screen alignment and cut/paste tutorial. But leaves you
without your precious preference settings and your documents, the clock is
reset, the regional settings are gone, etc.
In essence, you have a 'new' PPC.

A desktop computer doesn't do this as everything gets written back to disk
from RAM when you hit that shutdown button. At worst even when the desktop
OS decides it no longer wants to boot up, your settings and documents are
still there, but you just can't get in without a repair/bootdisk.
To give you a little buffer between the iminent death of your documents
and settings, modern PPC's have been equipped with a backup battery to
keep RAM powered even when you pull the main battery. although limited and
not strong enough to power the entire device, this was deemed 'enough' by
the PPC manufacturers, and to add another safeguard the PPC's were also
equipped with a backup facility that can detect whether the battery is
getting too low to operate, and will initiate a full backup to whatever
storage space you assigned it to (internal store or a card, for example)
so you may restore after power faillures.
A part I forgot to explain was that most PPC's also have a part of ROM
that is left over from storing the OS, (Think iPAQ FileStore here) and is
made user accessible so you can store some of your own programs and data
there. HP's new iPAQ's are now sporting up to 128MB Flash ROM of which
almost half is available for the user to store his/her data into without
risking the loss of this data when the device loses power. Flash ROM does
not need any power to retain data. A downside of the ROM is that it is
slower than RAM, and has limited write cycles available (think of it as a
CD-RW, only with many many more cycles) You don't have to expect Flash ROM
to suddenly fail on your PPC however, the internal technology is advanced
enough to outlast your PPC's life with typical use.
Also a lot of PPC's have expansion slots that can take more flash memory
in the form of Multimedia/Secure Digital/Compact Flash cards, and some
fancy PPC's even sport an USB host port so you can use USB sticks.
Mind you, external storage like that does not add to the PPC's RAM.
(we'd love that, but alas) It can be an intricate world for PPC's!

I hope that was coherent enough. it's early ;)

~S.

"Dott. Ing. Andrea NOTARI" <anotari@libero.it> wrote in
news:O7gQXza0EHA.1940@TK2MSFTNGP15.phx.gbl:

> Hi again ACE,
> just after reading your answer to my third question, I believed I got
> the main point. However, after discussing with a few friends some days
> later, the following doubt arose:
> you say that whatever stored in the windows registry gets lost if the
> litium battery expires (let's forget about the back-up battery for
> simplicity). But if I consider an ordinary personal computer, I suppose
> I can find the same win registry utilized by the OS (e.g. XP). But when
> I shut the machine off, and on again the next day, I have lost nothing.
> Whereas you say it's not the same with a PPC and back-up solutions are
> needed to retrieve data. Now, I wonder where the difference lies between
> a PPC and an every-day PC...
>
> Thanks again for your informative reaction.
>
> ANdrea
> 

-- 
======================
ACE!!! a.k.a. ~S.
OS. Osaris / Psion 5mx
iPAQ 5550 / Nokia 6310
http://www.xarane.com
======================
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