Microsoft FAT Patents valid

The Inquirer reports:

THE US Patent and Trademark Office has declared that patents Microsoft holds on file allocation tables (FAT) are valid, opening up the question once more on how Linux will be affected.

The Linux OS uses the FAT file system.

If you use a Microsoft box, as I do, you know about FAT files, because of course your machine blows up on a fairly regular basis and you get to look under the hood far more than you ever bargained for. Here‘s what makes FAT so phat:

File systems have come a long way since MS-DOS and early versions of Windows. Those operating systems organized files under the FAT file system, which represents logical areas of the disk in allocation units called clusters, and maps the locations of file data to those areas using a file allocation table (FAT). FAT is also called FAT16 because it uses a 16-bit address space for tracking files and clusters.

FAT clusters vary with the size of the disk. FAT’s 16-bit address space can support up to 65,536 clusters (216). With a 65MB disk, cluster sizes were just 1KB in size, but they ballooned as disks emerged that were able to hold gigabytes of data. And since only a single file can be written to a cluster, this created inefficiencies that ended up wasting as much as 50% of available space on a 2GB disk drive.


FAT32, which debuted with Windows 95 OEM Service Release 2 (OSR2), introduced a 32-bit address space. By increasing the size of the file allocation table, it could support more clusters that were smaller in size on large disk drives, reducing the potential for wasted drive space.

Another FAT32 innovation was that it could handle file names with up to 255 characters, whereas FAT could only handle names with up to eight characters. Users could finally create long file names to better describe the contents.

The advent of FAT32 extended the maximum addressable volume size from 2GB to 2TB and improved reliability by allowing the system to switch to a copy of the file allocation table if the default copy should become damaged. But FAT32 also added to file system overhead and was therefore inefficient to run on disks smaller than 260MB.

Whatever it is, and as much as Microsoft is the software developer we all love to hate, evidently this works well enough for Linux to want to use it. It brings to mind Mr. Bill’s recent statement that, despite its oligopolistic tendency to snarf up all sorts of businesses and business sectors, Microsoft considers its main competition to be, not Google, but IBM. Think those thoughts.


Dan Ravicher, [the Public Patent Foundation]’s executive director and founder, said, “If Microsoft sues anyone for infringing them, the defendant in any such suit can raise any defense they’d like, including invalidity, and even including invalidity in light of this same prior art.”

Indeed, “The patent office’s decision has no preclusive effect on a court, and there are indeed cases where the patent office made a decision in a re-examination supporting a patent and a court later looked at the same exact issue, disagreed with the PTO, and found the patent invalid,” said Ravicher.

True, but it does sound a little overheated, maybe even desperate. All things considered, this is a result that Microsoft — and anyone similarly situated — would want. If it had come out the other way, I don’t expect he would have said the same thing, do you?

UPDATE: Blogger Different River writes:

Mr. Coleman,

I was going to leave a comment on this post[.] But when I clicked on “leave a response” nothing happened. (Yes, having problems with my comments — RDC.)

Anyway, the article you quote says that “The Linux OS uses the FAT file system.” This is true, but leaves an incorrect impression –that Linux can’t exist without this Microsoft-owned system.

The Linux OS has its own native filesystem, ext3 (there is an earlier version called ext2). There are alternative filesystems available also, such as reiserfs, which some peopel believe in like a religion, and I suppose these different systems are optimal for differentpurposes.

Linux can also use FAT, but the only reason anyone would use FAT under Linux would be on a machine configured to run both Windows and Linux (but not at the same time — you have to choose when you boot up the computer. Linux would use FAT to access a Windows drive partition, or to share data with the Windows system (not in real-time of course;after the next reboot).

Of course, lots of people do this — it enables you to have both Windows and Linux while owning only one computer, and to have at least some of the data accessible regardless of which OS you are running at the moment. For a long time, I had on a single computer (1) a FAT32 partition for Windows, (2) an ext3 partition for Linux, and (3) a FAT32 partition for data that I wanted to be able to access in eitherOS. I think this is very common.

If the result of this holding is that Linux systems can no longer access FAT disk partitions, Linux would lose that capability. But the impression left by the unqualified statement “The Linux OS uses the FAT file system” leaves the imrpession that without FAT, Linux isdead. And that’s not even close to being true.
Furthermore, after Windows Me (or maybe 98), the default filesystem for Windows is NTFS, not FAT. And Linux doesn’t deal with NTFS very well. For someone running (say) WinXP and Linux, it won’t work to pass data between the two OSs on an NTFS partition, but Linux seems to be surviving anyway.


I certainly did not mean to imply that Linux was dead or even mortally injured.  This is a development to watch, however.  Thanks, DR!


Author:Ron Coleman

I write this blog.

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