From LQWiki

FAT-12 - FAT stands for File Allocation Table, and is a system used by Microsoft to create filesystems on disks. FAT-12 uses a 12-bit addressing scheme, as opposed to the 16 or 32 bit schemes used by later filesystems. FAT-12 was used on hard drives up to 32 Mb (Yes, Virginia, they used to make them that small.) It is currently used on floppy diskettes under DOS and Windows. Linux can format/read/write to FAT-12 floppies.