What kind of cell is there in a Serial flash?

I am surveying a serial flash for storing data.
I found the datasheet do not definitely mention the flowwing issues:

1. What is there, NOR or NAND type cell, in a SERIAL FLASH?
2. Is a wear-leveling necessary for a serial Flash?

Is anyone can tell me?
Grateful to any comment.
Thanks.

Hmm...
Here "serial" means SPI.
e.g.
Serial Flash from ST:
http://www.st.com/stonline/products/families/memories/fl_ser/index.htm

Serial Flash from Chingistek:
http://www.chingistek.com/products/spi.cfm

Serial Flash from ATmel:
http://www.atmel.com/dyn/products/param_table.asp?family_id=668&OrderBy=part_no&Direction=ASC

How about the Bad Block Management.
Is it neccessary?

"York" <yukuan.jiang@gmail.com> wrote in message
news:1147855321.575401.47450@u72g2000cwu.googlegroups.com...
> How about the Bad Block Management.
> Is it neccessary?

If the blocks are not power-of-two sized eg 528 then the extra bytes are
intended for error correction, which means errors are to be expected.

Peter

Good Point. :)

"York" <yukuan.jiang@gmail.com> wrote in message
news:1147857121.450054.300740@j55g2000cwa.googlegroups.com...
> Good Point. :)

What point?
Please quote the context so us mortals can follow.

Peter

Peter Dickerson wrote:
> "York" <yukuan.jiang@gmail.com> wrote in message
> news:1147857121.450054.300740@j55g2000cwa.googlegroups.com...
> > Good Point. :)
>
> What point?
> Please quote the context so us mortals can follow.

Sorry! (I miss press the reply button.)
I means it is a good point as follows.

Peter Dickerson wrote:
> If the blocks are not power-of-two sized eg 528 then the extra bytes are
> intended for error correction, which means errors are to be expected.

York wrote:
> I am surveying a serial flash for storing data.
> I found the datasheet do not definitely mention the flowwing issues:
> 
> 1. What is there, NOR or NAND type cell, in a SERIAL FLASH?
> 2. Is a wear-leveling necessary for a serial Flash?

I've been told by an authoritative source
that SST serial flash uses exactly the same
NOR structure as their parallel flash.

>> How about the Bad Block Management.
>> Is it neccessary?
>
> If the blocks are not power-of-two sized eg 528 then the extra bytes are
> intended for error correction, which means errors are to be expected.
>
> Peter
>

That is a load of dingos kidneys...
Errors are to be expected in NAND flash devices, but not in NOR flash 
devices.
The device organisation has nothing to do with how the memory cell operates.

There is a finite number of erase cycle on any flash memory.
Errors are ALWAYS to be expected when you are close to the limit on erase 
cycles
The errors that will occur, results in bits not beeing able to erase 
properly.

The AT45 is NOR based and not NAND based so there should be no difference in 
errors
compared to a standard parallel flash memory.
Adding extra bytes (like in the AT45 series) will allow you to extend the 
life of the device BEYOND
the 50,000-100,000 cycles specified in the device (never devices are better 
than the original devices).

Some other key AT45 advantages are
* Small sector size (256-1024 bytes + extra)
* Dual SRAM databuffers allows fast read/modify write
* Common pinout from 1 Mbit to 64 Mbit.


Wear leveling is required for any flash.
Again the extra bytes helps because you can keep wear leveling info inside
the block.
Simplifies a lot

-- 
Best Regards,
Ulf Samuelsson
This is intended to be my personal opinion which may,
or may bot be shared by my employer Atmel Nordic AB

I finally found that almost all Serial Flashes uses NOR gates in their
memory cells. Error correcting mechanism is not necessary for NOR
type flashes. The wear-leveling is easy since NOR flash is byte-
programmable and leaving the factory with no bad memory cell.

Thanks for all you.
Thank you.

Jim Stewart wrote:
> York wrote:
> > I am surveying a serial flash for storing data.
> > I found the datasheet do not definitely mention the flowwing issues:
> >
> > 1. What is there, NOR or NAND type cell, in a SERIAL FLASH?
> > 2. Is a wear-leveling necessary for a serial Flash?
>
> I've been told by an authoritative source
> that SST serial flash uses exactly the same
> NOR structure as their parallel flash.