[ECOS] FAT32 over NAND

Jonathan Larmour jifl@eCosCentric.com
Wed Jan 21 02:18:00 GMT 2009

Paul D. DeRocco wrote:
>>From: Jonathan Larmour
>>There are also patent issues. FTLs are covered by patents by M-Systems,
>>Inc. in the US and Europe at least. You cannot develop or sell a product
>>containing an FTL in those markets without getting a licence from
>>(unless it's used in a PCMCIA device, for which M-Systems grants a
>>no-royalty licence).
> The SmartMedia specification, originally from May 1999, establishes a
> standard for reading and writing SmartMedia cards, which are just single
> NAND flash chips in a pluggable package, and it describes how a FAT16 file
> system must map to the flash chip, by aligning the cluster boundaries to the
> erasable block boundaries. There is no support for wear leveling beyond what
> can be done while the power is turned on (i.e., maintaining a rover for
> allocating the next block), and FAT16 is limited to 64K clusters which makes
> it appropriate only for smaller sizes. Does the M-Systems patent cover any
> translation layer one might write for a SmartMedia card?

That implementation doesn't sound like an FTL, but then without things 
like wear-levelling or dealing with the inevitable bad blocks, it doesn't 
sound terribly useful either! I doubt that that conflicts with the patent. 
You could write a (non-standard) FTL that worked on top of it of course, 
but that's presumably not what you're talking about.

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