File Allocation Table

FAT
Developer(s)	Microsoft, NCR, SCP, IBM, Compaq, Digital Research, Novell, Caldera
Full name	File Allocation Table
Variants	8-bit FAT, FAT12, FAT16, FAT16B, FAT32, ExFAT, FATX, FAT+
Introduced	1977 with Standalone Disk BASIC-80
Partition IDs	MBR/EBR: FAT12: 0x01 e.a. (Extended Attribute); FAT16: 0x040x060x0E e.a.; FAT32: 0x0B0x0C e.a.; BDP: EBD0A0A2-B9E5-4433-87C0-68B6B72699C7;
Structures
Directory contents	Table
File allocation	Linked list
Bad blocks	Cluster tagging
Limits
Max volume size	FAT12: 32 MB (256 MB for 64 KB clusters); FAT16: 2 GB (4 GB for 64 KB clusters); FAT32: 2 TB (16 TB for 4 KB sectors);
Max file size	4,294,967,295 bytes (4 GB − 1) with FAT16B and FAT32
Max no. of files	FAT12: 4,068 for 8 KB clusters; FAT16: 65,460 for 32 KB clusters; FAT32: 268,173,300 for 32 KB clusters;
Max filename length	8.3 filename, or 255 UCS-2 characters when using LFN
Features
Dates recorded	Modified date/time, creation date/time (DOS 7.0 and higher only),; access date (only available with ACCDATE enabled),; deletion date/time (only with DELWATCH 2);
Date range	1980-01-01 to 2099-12-31 (2107-12-31)
Date resolution	2 seconds for last modified time,; 10 ms for creation time,; 1 day for access date,; 2 seconds for deletion time;
Forks	Not natively
Attributes	Read-only, hidden, system, volume, directory, archive
File system; permissions	FAT12/FAT16: File, directory and volume access rights for read, write, execute, delete only with DR-DOS, PalmDOS, Novell DOS, OpenDOS, FlexOS, 4680 OS, 4690 OS, Concurrent DOS, Multiuser DOS, System Manager, REAL/32: execute with only FlexOS, 4680 OS, 4690 OS;; individual file / directory passwords not with FlexOS, 4680 OS, 4690 OS;; world/group/owner permission classes only with multiuser security loaded; ; FAT32: Partial, only with DR-DOS, REAL/32 and 4690 OS;
Transparent; compression	FAT12/FAT16: Per-volume, SuperStor, Stacker, DoubleSpace, DriveSpace; FAT32: No;
Transparent; encryption	FAT12/FAT16: Per-volume only with DR-DOS; FAT32: No;

File Allocation Table (FAT) is a file system developed for personal computers and was the default filesystem for MS-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 drives capacity required three major variants: FAT12, FAT16 and FAT32. FAT was replaced with NTFS as the default file system on Microsoft operating systems starting with Windows XP. Nevertheless, FAT continues to be used on flash and other solid-state memory cards and modules (including USB flash drives), many portable and embedded devices because of its compatibility and ease of implementation.

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