NAND OOB Questions...

[Charles Manning]

On Monday 05 June 2006 20:14, Thomas Gleixner wrote:
> On Thu, 2006-06-01 at 09:38 -0700, Steve Finney wrote:
> > 1) The Samsung K9F56* NAND chip allows doing more than one write
> > to the OOB area of a page without an erase; the second write
> > may zero bits that were set to 1 by the first write. Is the Samsung
>
> Bits can not be set to 1 by the first write. FLASH cells are set to 1 by
> erasing and programming can set bits to 0.
>
> > chip unusual in this, or is this normal NAND behavior? (I believe
> > this would be normal for NOR flash).
>
> On NOR you can do this almost unlimited. NAND is much more restricted
> vs. write ordering.

Just one point of clarification that tglx might not have spelled out clearly 
here.

In both NAND and NOR you cannot set a 0 bit back to a 1 bit by programming. 
You can only do this by erasing the erasable block.

Where NOR and NAND differ is that if you program a pattern into NOR that tries 
to set a 0 to a 1 then (in most cases) the programming operation will be 
aborted. However, NAND will program the zeros only and 1 bits are just "don't 
care".