where and how are the programs stored? ROM ? Then How?

[Guest]

Hello,
When we deploy an application to the device using Visual Studio .NET,
the application is transfered to the device (PPC). As far as I know, Windows
Mobile operating systems,
do not have a file system, then where are these files ?

My guess is they are in ROM besides the O/S,
but I have no idea how the management or how many percent of ROM is reserved
for this operation.

and I have heard that Windows Mobile 5.0 supports persistant storage, is
this a disk with a file system?

If someone can clear my conflicts, I will be happier.

rifat yavuz
Microsoft Academic, Turkey

 

[Paul G. Tobey [eMVP]]

Sure they do. They might have several, in fact. The basic filesystem on
most devices is RAM-based. Many have a non-volatile folder off the root,
\Flash, \PSM, or whatever, which is Flash-based.

Some files in the RAM-based filesystem *are*, in fact, in ROM (programs in
the \Windows folder, for example).

Windows Mobile 5.0 will support a completely non-volatile filesystem.
Whereas, the root folder, the \Program Files folder, the \Windows folder are
now generally RAM-based, Windows Mobile 5.0 will support having all of those
places be Flash-based. When that happens, the \Windows folder won't be
dependent on the battery any more and, when the battery goes dead, you won't
lose the contents of your \Windows folder, etc.

Most Windows CE-based devices currently support PCMCIA cards that can
support files, too. An ATA Flash Compact Flash card, for example, will
appear as a \Storage Card folder on most devices. SD Cards can also be used
for this type of filesystem. Pocket PC devices don't generally support it,
but many Windows CE devices support hard disks for file storage.

Paul T.

 

[Daniel Moth]

You mentioned a few things but not RAM.. therein lies the answer...

Cheers
Daniel

 

[Guest]

Hello Paul,
Thanx for your great explanation. As I read the second paragraph,
I mentioned that I have very little knowledge about the situation when the
battery goes dead.

here I have my story, and would be so happy if you correct any of my
mistake.

ok, when we turn off the device or the battery goes dead, the ram is
flushed.(thats what we are taught at the uni. .)
when we turn it on, the windows folder and program files folder is read from
the ROM, and then loaded into RAM
where there is a special filesystem.

when we deploy a smart device application to the PPC device, the application
resides in that special filesystem that is
RAM-based. if we turn off the device this file system is written to ROM for
later retrieval. so when we turn on again we
can see the smart device application back in Program Files folder which is
mapped from a reserved area of ROM.
and if we delete the smart device application , its removed from RAM based
file system.. and upon turning the device off again, ROM is updated as if
synched with RAM-based file system. so the story goes....

am I correct?
thanx
Rifat

 

[Paul G. Tobey [eMVP]]

Sort of, yes. The RAM filesystem isn't actually copied from ROM, but you
can pretend that's what's going on.

Are you telling us that you're writing your program to non-volatile memory
or asking if that's what happens? No, generally that's *not* what happens.
When you turn the power 'off', it's not really off on most battery-powered
devices. The processor is suspended, but battery power is still maintaining
the state of RAM, including the RAM filesystem. When you turn the device
back 'on', effectively just unsuspending it, everything is exactly where you
left it; it never moved and was maintained by power from the battery. If
you remove both the main battery and the emergency battery, your program
will be gone. There's no automatic copy to non-volatile memory on any
device that I've ever seen.

Paul T.

 

[Steve Maillet \(eMVP\)]

"ok, when we turn off the device or the battery goes dead, the ram is
flushed.(thats what we are taught at the uni. .)" That's not generally true.
If the battery goes dead without any hardware/software to detect it and save
data in RAM the RAM is toasted and the contents are lost.