Getting the Boot:VFAT

By Howard Gilbert

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 * Windows 95 and Windows NT use of FAT
 * Supports long file names

Windows 95 and Windows NT support VFAT. Technically, VFAT is not a new File System. It uses the same directory structure, format, and partition type as ordinary FAT. VFAT is simply a way to store more information in the FAT directory.

The most important feature of VFAT is the ability to store long file names. Since it is built on ordinary FAT, each file has to have an 8 character name and 3 character extension. However, VFAT then allocates additional directory blocks to hold a longer file name.

Programs running in DOS, OS/2, and Linux (and old 16-bit Windows programs) will not see the longer file name. Only WIN32 programs running in NT or Windows 95 can make use of the longer name.

Because VFAT uses the old FAT directory to add some unusual new entries, the VFAT additions can be damaged if the disk is manipulated by a DOS or OS/2 disk utility that does not understand the new structure. Even a simple DEL command under OS/2 for a FAT dataset with a long file name can leave the extra blocks in the directory. The Windows 95 SCANDISK utility can be run later to audit the VFAT structure and delete the extra directory blocks for files that no longer exist.

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