Microsoft's FAT patent and licensing page

Method and system for accessing a file using file names having different file name formats filed 1992, granted 1998
Common name space for long and short filenames filed 1995, granted 1996
Common name space for long and short filenames filed 1996, granted 1998
Method and system for providing a common name space for long and short file names in an operating system filed 1997, granted 2001

This is really absurd. If you read the first three patents, their substance is that you can store long filenames alongside short ones and maintain a link between the two. If the person supplies a long filename you can abbreviate it to a unique string (like "abc-1.exe", "abc-2.exe" etc) in order to create the short file name for the older part of the system. You have to wonder why the patent clerk doesn't consider these ideas to be completely obvious. You don't have to be a computer programmer to see that these ideas are obvious.

The last patent, granted in 2001, really takes the cake. In this patent Microsoft claims its entire drive access API complete with register flags and interrupts along with more minutia concerning long file names. It's kind of ironic that Microsoft is claiming patents in an area where their whole system has long been seen as being particularly defective. The whole long filename thing is only necessary because of the poor design of the original operating system. I guess now obvious ad hoc hacks to fix it qualify as brilliant innovations deserving of patents.