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Virtual FAT (VFAT)

When Microsoft introduced Windows 95 in, well, 1995, they made several improvements to the operating system when compared to its predecessors. One of the changes made was an enhancement to the classical FAT16 file system that had been in use up until that point. The new variation of FAT was called Virtual FAT or VFAT for short. (Note that many people use the terms "FAT" and "VFAT" interchangeably, even though they are technically not the same. All "FAT" partitions created under Windows 95 or later operating systems are really VFAT partitions.)

VFAT has several key features and improvements compared to FAT12 and FAT16:

• Long File Name Support: One of the most annoying limitations of operating systems prior to Windows 95 was the eleven-character file name restriction. For most people, VFAT's most important accomplishment was enabling the use of long file names by the Windows 95 operating system and applications written for it, while maintaining compatibility with older software that had been written before VFAT was implemented.
• Improved Performance: The disk access and file system management routines for VFAT were rewritten using 32-bit protected-mode code to improve performance. At the same time, 16-bit code was maintained, for use when required for compatibility.
• Better Management Capabilities: Special support was added for techniques like disk locking, to allow utilities to access a disk in "exclusive mode" without fear of other programs using it in the meantime.

Despite the new name and new capabilities, VFAT as a file system is basically the same as FAT. Most of the new capabilities relate to how the file system is used, and not the actual structures on the disk The only significant change in terms of actual structures is the addition of long file names. Even here, VFAT supports these using what is basically a hack, as opposed to anything really revolutionary. See the discussion of long file names for more information on how VFAT implements longer file names under Windows 9x/ME.

Note that as with FAT, much of the rest of the discussion of file systems in other subsections in this area of the site deals with VFAT.

Next: 32-Bit FAT (FAT32)

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