Design of the FAT file system
The FAT file system is a file system used on MS-DOS and Windows 9x family of operating systems. It continues to be used on mobile devices and embedded systems, and thus is a well suited file system for data exchange between computers and devices of almost any type and age from 1981 through the present.
| Developer(s) | Microsoft, SCP, IBM, Compaq, Digital Research, Novell, Caldera |
|---|---|
| Full name | File Allocation Table: FAT12 (12-bit version), FAT16 (16-bit versions), FAT32 (32-bit version with 28 bits used), exFAT (64-bit versions) |
| Introduced | 1977 (Standalone Disk BASIC-80) FAT12: August 1980 (SCP QDOS) FAT16: August 1984 (IBM PC DOS 3.0) FAT16B: November 1987 (Compaq MS-DOS 3.31) FAT32: August 1996 (Windows 95 OSR2) exFAT: November 2006 (Windows Embedded CE 6.0) |
| Partition IDs | MBR/EBR: FAT12: 0x01 e.a.FAT16: 0x040x060x0E e.a.FAT32: 0x0B0x0C e.a.exFAT: 0x07 e.a.BDP: EBD0A0A2-B9E5-443387C0-68B6B72699C7 |
| 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 right only with 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 |
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