File Allocation Table
family of file systems originally developed by Microsoft
File Allocation Table (FAT) is a file system developed for personal computers and was the default file system for the DOS and Windows 9x operating systems. Originally developed in 1977 for use on floppy disks, it was adapted for use on hard disks and other devices. The increase in disk drive capacity over time drove modifications to the design that resulted in new versions: FAT12, FAT16, FAT32, and exFAT.
FAT was replaced with NTFS as the default file system on Microsoft operating systems starting with Windows XP. Nevertheless, FAT continues to be commonly used on relatively small capacity solid-state storage technologies such as USB flash drives, SD cards, MultiMediaCards (MMC) and eMMC because of its compatibility across operating systems and embedded systems, and ease of implementation.
Uses
Historical
FAT was used on hard disks throughout the DOS and Windows 9x eras. Microsoft introduced NTFS with the Windows NT platform in 1993, but FAT remained the standard for the home user until the introduction of Windows XP in 2001. Windows Me was the final version of Windows to use FAT as its default file system.
For floppy disks, FAT has been standardized as ECMA-107 and ISO/IEC 9293:1994 (superseding ISO 9293:1987). These standards cover FAT12 and FAT16 with only short 8.3 filename support; long filenames with VFAT were partially patented. While FAT12 is used on floppy disks, FAT16 and FAT32 are typically found on the larger media.
Modern
FAT is used internally for the EFI system partition in the boot stage of EFI-compliant computers.
The public source identifies “File Allocation Table” as family of file systems originally developed by Microsoft. This brief keeps that definition visible, then builds a research path around File, Allocation and Table.
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This entry incorporates text from “File Allocation Table” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.