File Allocation Table 12. FAT12 is the name used to refer to the original version of the FAT file
system which was introduced in 1980. It only supports volumes up to a maximum of 16 megabytes.
Initially it did not support a hierarchy of directories. Support for hierarchical directories was
added later. The 12 in FAT12 comes from the fact that a 12 bit binary number is used to store the
cluster number being addressed. FAT12 is commonly referred to as FAT. It is the files system used
on floppy diskettes. FAT12 does not natively support alternate data streams or file
permissions and it is not a journaling file system.