Re: curious questions

[Markus Schiltknecht <markus@bluegap.ch>]

Hi,

thanks for your quick answer!

Jörn Engel wrote:
> You can erase no less than one erase-block.  For NAND, you cannot easily
> write less than one page.  Sometimes subpage writes work, sometimes they
> don't, they have strange limitations and are best ignored in the
> beginning.

So, with mtd, I can erase the erase-block spanning pages 0 to 63, and 
then, write to page 0, wait for more data and only then write page 1, right?

>> Can I repeatedly write to a NAND flash page, to set its bits to 1 
>> (without resetting any bit to 0) (or vice-versa for XOR)?
> 
> Erase sets bits to 1, writes sets them to 0.

Ah, that applies to NAND as well as NOR, good.

> With old NOR flashes, you can repeatedly write the same area to flip
> single bits.  Writes with all 1's are essentially noops, so to set a
> single bit write a word will all but one bit set to 1.  With ECC you'd
> have to flip bits on the ECC backwards, which doesn't work.  NAND has
> ECC, so ordinarily this trick won't work.

Yeah, ECC certainly wouldn't work for that. Good explanation, thanks.

Markus