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Entry type: FAQ Entry ID: 7222410, Entry date: 04/17/2001

Definition of terms: FAT file system

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What is to be understood by the "FAT" file system?

The FAT file system is the file system used by MS-DOS to organize and manage files. The "FAT" (=File Allocation Table) is a data structure that MS-DOS generates when formatting on the floppy disk.

When MS-DOS saves a file on a formatted floppy disk, the operating system stores the information about the saved file in the FAT, so that MS-DOS can call the file again when requested to do so later. MS-DOS can only use the "FAT" type as file system.

There are two FAT file systems: "FAT16" (usually also call "FAT") and "FAT32". Both file systems have different sizes of partitions and clusters. "FAT32" is supported by the Microsoft operating systems only from Windows 95B and higher. This means that the MS-DOS, Windows 3.x and Windows NT systems do not support the FAT32 system. Therefore, data stored on a partition of the "FAT32" type cannot be read from these systems.


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