Penguin
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FAT12 was Microsofts File system designed for floppies.

FAT is an acronym for File Allocation Table, which refers to the table which lists where on the disk files are stored.

The reason it is called FAT12 is that each Cluster is represented in the File Allocation Table by a 12 bit number. Some values:

|^Value|^Meaning |>000|<The cluster is unused and available |>FF7|<The cluster has a bad sector in it and will not be allocated |>FF8-FFF|<The last claster of a file |>other|<The cluster number of the next cluster in the file.

Usually the FAT is stored as the second cluster on the disk, there are two copies kept, so if one is corrupted the other can be refered to. The first cluster is the boot sector and contains a table of how the disk is layed out.

Note that FAT12 can only address up to 64mb in size, so FAT16 was introduced.

FAT12 also has the 8.3 filename charactoristics.