Microsoft’s FAT Patent Rejected

The U.S. Patent Trademark Office has rejected all claims to patents for a
Windows file format held by Microsoft.

Under a reexamination process initiated earlier this year by the recently
formed Public Patent Foundation (PUBPAT), The USPTO rejected all claims of Microsoft’s technology, which includes its internally developed FAT Allocation Table
(FAT) file system . The FAT file system is one of the technologies Microsoft has placed in its royalty-bearing licensing portfolio.

The patents came under scrutiny after critics claimed that the licensing
policy was the beginning of Microsoft’s efforts to shut down Linux. Linux
support for FAT32, used in today’s systems, started with the 2.0.34 kernel.

“The Patent Office has simply confirmed what we already knew for some
time now, Microsoft’s FAT patent is bogus,” Dan Ravicher, PUBPAT’s executive
director, said in a statement. “I hope those companies that chose to take a
license from Microsoft for the patent negotiated refund clauses, so that they
can get their money back.”

In its defense, Microsoft said it had not claimed
control over the entire FAT system, but only over the technology that has been built
up around the original code.

“We have some rights, but no one person has firm, strong control over all
aspects of FAT,” David Kaefer, director of business development for
Microsoft’s intellectual property and licensing unit, told the Associated

The ruling is just the first step in a very lengthy process. Microsoft
now has a few months to appeal the USPTO decision as part of what’s known as
“patent prosecution,” a process to determine whether the patent should
stand. The Patent Office examiner will look at the response and may modify
the ruling. At that point Microsoft has the opportunity to respond to that.
Then when the examiner makes a final ruling. Microsoft has the right to take
its case to the U.S. Supreme Court. Analysts say patent prosecution can be a
process as lengthy as the appeal of a patent infringement case.

However, Ravicher said third party requests for reexamination, like the one
filed by PUBPAT, are successful in having the subject patent either narrowed
or completely revoked roughly 70 percent of the time.

What is FAT File?

The FAT file system is used to keep track of the location and sequence of
specific files stored on a PC’s hard drive, a floppy disk or a flash memory
card. Most operating systems store computer files by dividing the file into
smaller pieces and storing them in separate clusters. The FAT file system,
first developed in the 1970s by Bill Gates, lets the OS keep track of
each file within the clusters and identify unassigned clusters for new

When a computer user wants to read a file, the FAT file system reassembles each piece of the file into one unit for viewing. Microsoft
explained that the FAT file system was based on the BASIC programming
language and was developed to allow programs and data to be stored on

Microsoft describes its patent as “the ubiquitous format used for
interchange of media between computers, and, since the advent of
inexpensive, removable flash memory, also between digital devices.”

The license covers four patents:

  • 5,579,517: “Common name space for long and short filenames”
  • 5,745,902: “Method and system for accessing a file using file names
    different file name formats”
  • 5,758,352: “Common name space for long and short filenames”
  • 6,286,013: “Method and system for providing a common name space for long
    and short file names in an operating system”

All four of these patents deal with the virtual FAT , a
system driver that acts as an interface between an application and the system’s
FAT. One of the limitations of the FAT file system technology is that it
can store only files with eight-letter words; VFAT allows for the longer
file names commonly used to today.

Pricing for the Fat file system license has been set at 25 cents per unit,
with a cap on total royalties of $250,000 per manufacturer. The 25 cents per
unit fee is available for devices that use removable media to store data,
including PDAs, digital cameras, digital camcorders and portable digital
audio players.

Even if Microsoft were to levy a charge against everyone — not just the
manufacturers, as it does under the current licensing policy — it would only affect
the use of VFAT technology.

Companies that wanted to continue using FAT and avoid the license fees
could do so by taking out the VFAT system driver and forcing customers to
come up with eight-letter filenames.

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