[maemo-users] What is flash?

From: rob at myvoice.nl rob at myvoice.nl
Date: Tue Jul 22 10:28:21 EEST 2008
Karl got NAND and NOR swapped (read at the bottom).

"Flashing your n810" means that the NAND flash will be erased and new  
software version will be downloaded to your device and stored in the  
NAND flash.

So if you flash your n810 (or n800 or n770), all data is removed from  
flash and a brand new Linux OS will be written into the flash. Since  
all user data (bookmarks, contacts, media files, ...) is also written  
in flash this data is lost while flashing your device.

With Diablo for the n810 there is an end to flashing (and thus loosing  
all your data). Now a same mechanism as on the PC is used: packages  
are updated via a package manager so a new kernel, libraries or a  
Nokia application can automatically be installed. I do not know if  
this is only done on a user request or if you have to initiate this  
yourself. Unfortunately my n810 got fried after 1 day and I was unable  
to install Diablo :-( (will hopefully get a new one this week).

Quoting Karl Kobel <karlkobel at sbcglobal.net>:

> NAND is like non-volatile RAM and is used for program execution. It
> takes more space to create a bit, so are smaller in size. Not sure, but
> I don't believe this type is used in the Nokia's.
> NOR is higher in density, and is the type used in SD cards.

It's the other way around:

NOR flash is used for program execution, NAND for SD cards and such.
Normally both types are used: a small NOR flash contains a program  
(called boot-loader) to load the real software from NAND flash into RAM.
After loading and unpacking (sometimes images are stored in NAND flash  
in a kind of .zip file) the real software (Linux kernel) will be  

If you like to compare this to your PC then the BIOS is NOR flash  
(this is where the boot-loader is stored that will load the software  
from your hard disk) and the hard disk can be compared with the NAND  



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