What’s what with Microsoft’s patent claims, and a modest suggestion on how to avoid all this patent nonsense now, and in the future: Get the FAT out!
At first glance, Microsoft suing TomTom, the navigation device manufacturer, for patent violations, appeared to be patent business as usual. A closer look at the Microsoft/TomTom lawsuit (PDF Link) showed that three of Microsoft’s eight patents don’t concern navigation systems, but file system usage within TomTom’s Linux-powered devices.
Specifically, Microsoft is claiming that TomTom, and by implication Linux, is in violation of U.S. Patent No. 5,579,517 (“the ’517 patent”l), entitled “Common Name Space for Long and Short Filenames;” U.S. Patent No. 5,758,352 (“the ’352 patent”), entitled “Common Name Space for Long and Short Filenames;” and U.S. Patent No. 6,256,642 (“the ’642 patent”), entitled “Method and System for File System Management Using a Flash-Erasable, Programmable, Read-only Memory.”
While the names of the first two patents are identical, they actually refer to two different aspects of using ‘long’ file names in file systems. In older, 16-bit Microsoft FAT (File Allocation Table) and NTFS (New Technology File System) file systems supported a maximum of 8 characters for the base file name and 3 characters for the file extension. Including the dot separator, this gave 16-bit systems a maximum of 12-characters for a name. With the advent of 32-bit operating systems, the methods in these patents were introduced to ensure backwards compatibility between MS-DOS, early versions of NT, and Windows 2 and 3.x and later Windows operating systems such as Windows 98. The last patent covers a way to handle these file systems on Flash memory.