FAT8

FAT8 (Original 8-bit FAT; a variety of FAT, which stands for File Allocation Table) is a simple filesystem with limited capabilities. The "8" refers to the number of bits in table entries. This was the original version of FAT created at Microsoft for use with versions of BASIC that had built-in disk support; it was then adopted by Tim Patterson of Seattle Computer Products, who adapted it into FAT12 for use in his disk operating system that eventually got licensed to Microsoft (and in turn to IBM) as PC-DOS / MS-DOS.

Resources

 * Wikipedia