Linked by Eugenia Loli on Tue 10th Jan 2006 23:44 UTC, submitted by Derek Newhall
Microsoft After 2 years of examination the U.S Patent and Trademark Office has reversed its two earlier unofficial decisions and decided that Microsoft's File Allocation Table file system constitutes a "novel and non-obvious" system enabling it to be patented. This coupled with Microsofts plans to charge licensing fees for use of the system could cause many problems for open-source operating systems that implement the file system, or even to mp3 players. Elsewhere, has an interview with Microsoft's "open source point man" Martin Gregory.
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by Treza on Wed 11th Jan 2006 12:05 UTC
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Some remarks
- AFAIK, the patent concerns the handling of long filenames in FAT filesystems, not the FAT filesystem itself.
- The principle of operation of FAT is quite good for size limited devices, it is superior to ext2 for example, except for the broken filename handling and file ownership attributes.
- Maybe a filesystem targeted to FLASH medias should try to balance the number of writes in the whole area because FLASH/EEPROM cells are write/erasure cycles limited. The FAT Table is modified after all writes in the FAT filesystem which is no good for FLASH ( but maybe actual flash disk chips have provisions for enabling extra writes in that region, I don't know )
- The FAT filesystem was derived from Digital Research CP/M filesystem, from day 1 the limited filename length was a problem ( back at that time, 25+ years ago, Apple ][ DOS wasn't limited ). Many ways to overcome that problem was developped, for example OS/2 and the CDROM "RockRidge ISO9660" used an extra file with long filenames or filenames with Upper/lowercase caracters, spaces and accents. There are still problems between Windows and Linux concerning the range of allowable characters and filenames on CDROMs.
- There were many previous works of dealing with FAT problems anterior to Microsoft's solution, these ways weren't mainstream because of 2 reasons :
- Microsoft did never support these extensions.
- The best way to handle that was to slightly alter the format of directory sectors, and Microsoft could have developped a new version of DOS that could totally break the compatibility with 'enriched content' directories : The separate file concept of 'RockRidge' allows full backward compatibility whereas altering directories can break it if Microsoft wants it.
What's impressive is that Microsoft delivered a broken format, everyone knew it, everyone could have developped a new format or alter that format easily but only Microsoft could fix it in a fully Microsoft-compatible way.
- I think that some flash card vendors have officially licenced the FAT filesystem to Microsoft ( Sandisk )

There is a general threat with formats controlled too heavily by a single entity, for example, more and more PDF files ( datasheets, ... ) only works with the latest version of Adobe Acrobat Reader : You will be forever allowed to produce PDF files but with the complexification of the PDF format, it will be more and more difficult to process these files. In such domains, the differences pushed by RMS and the FSF between free and 'libre' are cleary shown : Basically FAT and PDF are free use, but not 'libre', a malicious corporation can screw you at any time.

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