View source for File Allocation Table

{{Short description|File system used by MS-DOS and Windows 9x}}
{{further|Design of the FAT file system}}
{{Use mdy dates|date=April 2016|cs1-dates=y}}
{{Use American English|date=July 2018}}
{{Anchor|FASTFAT}}<!-- for parked anchors -->
{{Infobox file system
| name = FAT
| image = 
| developer = [[Microsoft]]<!-- original FAT, FAT16, FAT32 -->, [[NCR Corporation|NCR]], [[Seattle Computer Products|SCP]]<!-- FAT12 -->, [[IBM]], [[Compaq]]<!-- Compaq MS-DOS 3.31-->, [[Digital Research]]<!-- lots of extensions -->, [[Novell]]<!-- lots of extensions continuing the DRI line of products -->, [[Caldera (company)|Caldera]]
| full_name = File Allocation Table
| variants = 8-bit FAT, [[#FAT12|FAT12]], [[#FAT16|FAT16]], [[#FAT16B|FAT16B]], [[#FAT32|FAT32]], [[exFAT]], [[#FATX|FATX]], [[#FAT+|FAT+]]
| introduction_date = {{Start date|1977}}
| introduction_os = [[Standalone Disk BASIC-80]]
| partition_id = [[Master Boot Record|MBR]]/[[Extended Boot Record|EBR]]:{{ubli
 | FAT12:&nbsp;<code>{{abbr|0x|Values in C-notation for hexadecimal numbers}}[[Partition type#PID_01h|01]]</code> e.a. (Extended Attribute)
 | FAT16:&nbsp;<code>{{abbr|0x|Values in C-notation for hexadecimal numbers}}[[Partition type#PID_04h|04]]</code><code>[[Partition type#PID_06h|0x06]]</code><code>[[Partition type#PID 0Eh|0x0E]]</code> e.a.
 | FAT32:&nbsp;<code>{{abbr|0x|Values in C-notation for hexadecimal numbers<span id="FAT32X"></span>}}[[Partition type#PID_0Bh|0B]]</code><code>[[Partition type#PID_0Ch|0x0C]]</code> e.a.
 | [[Basic data partition|BDP]]: <code>EBD0A0A2-B9E5-4433-87C0-68B6B72699C7</code>
 }}
| directory_struct = Table
| file_struct = [[Linked list]]
| bad_blocks_struct = Cluster tagging
| max_file_size = 4,294,967,295 bytes (4&nbsp;[[gigabyte|GB]] − 1)<!-- 2^32 − 1 --> with FAT16B and FAT32<ref name="GB4" />
| max_files_no = {{ubli
 | FAT12: 4,068 for 8&nbsp;[[kilobyte|KB]] clusters <!-- 2^12 − 12 (reserved clusters) − 16 (number of 8&nbsp;KB clusters for directory entries) -->
 | FAT16: 65,460 for 32&nbsp;KB clusters <!-- 2^16 − 12 (reserved clusters) − 64 (number of 32&nbsp;KB clusters for directory entries) -->
 | FAT32: 268,173,300 for 32&nbsp;KB clusters <!-- 2^28 − 12 (reserved clusters) − 262144 (number of 32&nbsp;KB clusters for directory entries) -->
 }}
| max_filename_size = [[8.3 filename]], or 255 [[UCS-2]] characters when using [[Long filename|LFN]]<ref group="nb" name="NB_LFN_UNI">Since [[Windows 2000]], Microsoft Windows uses [[UTF-16]] instead of [[UCS-2]] for the [[Unicode in Microsoft Windows|internal "Unicode"]]. In UTF-16, a "character" (code point) may take up two code units.</ref>
| max_volume_size = {{ubli
 | FAT12: 32&nbsp;[[megabyte|MB]]<!-- with 2^16 sectors á 512 bytes, or with 8&nbsp;KB clusters --> (256&nbsp;MB for 64&nbsp;KB clusters<!-- and EBPB -->)
 | FAT16: 2&nbsp;GB (4&nbsp;GB for 64&nbsp;KB clusters)
 | FAT32: 2&nbsp;[[terabyte|TB]] (16&nbsp;TB for [[4Kn|4 KB sectors]])
 }}
| dates_recorded = {{ubli
 | Modified date/time, creation date/time (DOS&nbsp;7.0 and higher only),
 | access date (only available with [[ACCDATE (CONFIG.SYS directive)|ACCDATE]] enabled),<ref name="Microsoft_2006_ACCDATE" />
 | deletion date/time (only with DELWATCH 2<!-- with Novell DOS 7, Caldera OpenDOS 7.01, DR-DOS 7.02 and higher -->)
 }}
| date_range = [[Epoch of 1980-01-01|1980-01-01]] to [[Year 2100 problem|2099-12-31]] ([[Year 2108 problem|2107-12-31]])
| date_resolution = {{ubli
 | 2&nbsp;seconds for last modified time,
 | 2&nbsp;seconds for creation time,
 | 1&nbsp;day for access date,
 | 2&nbsp;seconds for deletion time
 }}
| forks_streams = Not natively
| attributes = [[FAT file attributes|Read-only, hidden, system, volume, directory, archive]]
| file_system_permissions = {{ubli
 | FAT12/FAT16: File, directory and volume access rights for [[FAT file access rights|read]], [[FAT file access rights|write]], [[FAT file access rights|execute]], [[FAT file access rights|delete]] only with [[DR-DOS]], [[PalmDOS]], [[Novell DOS]], [[OpenDOS]], [[FlexOS]], [[IBM 4680 OS|4680&nbsp;OS]], [[IBM 4690 OS|4690&nbsp;OS]], [[Concurrent DOS]], [[Multiuser DOS]], [[Datapac System Manager|System Manager]], [[REAL/32]]: {{ubli
  | execute with only FlexOS, 4680&nbsp;OS, 4690&nbsp;OS;
  | individual file / directory passwords not with FlexOS, 4680&nbsp;OS, 4690&nbsp;OS;<!-- at least I could not find any user or programmer's documentation for it so far -->
  | [[FAT file access rights|world/group/owner]] permission classes only with multiuser security loaded
  }}
 | FAT32: Partial, only with DR-DOS, REAL/32 and 4690 OS<!-- version 2 and higher -->
 }}
| compression = {{ubli
 | FAT12/FAT16: Per-volume, [[SuperStor]], [[Stacker (disk compression)|Stacker]], [[DoubleSpace]], [[DriveSpace]]
 | FAT32: No
 }}
| encryption = {{ubli
 | FAT12/FAT16: Per-volume only with [[DR-DOS]]
 | FAT32: No
 }}
| data_deduplication = 
| copy_on_write = 
| OS = 
}}

'''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.<ref>{{Cite web |title=File Allocation Table (FAT): What It Is, Types, Versions, Advantages & Disadvantages |url=https://www.includehelp.com/operating-systems/file-allocation-table-fat.aspx |access-date=2025-06-01 |website=www.includehelp.com}}</ref> Originally developed in 1977 for use on [[floppy disk]]s, it was adapted for use on [[Hard disk drive|hard disks]] and other devices. The increase in disk drive capacity over time drove modifications to the design that resulted in versions: [[#FAT12|FAT12]], [[#FAT16|FAT16]], [[#FAT32|FAT32]], and [[exFAT]]. 

FAT was replaced with [[NTFS]] as the default file system on Microsoft operating systems starting with [[Windows XP]].<ref>{{cite web |url=https://windows.microsoft.com/en-us/windows-vista/comparing-ntfs-and-fat-file-systems |title=Comparing NTFS and FAT file systems |publisher=Microsoft |access-date=2014-01-27 |archive-date=2016-06-20  |archive-url=https://web.archive.org/web/20160620004455/http://windows.microsoft.com/en-US/windows-vista/Comparing-NTFS-and-FAT-file-systems |url-status=live }}</ref> Nevertheless, FAT continues to be commonly used on relatively small capacity [[solid-state storage]] technologies such as [[USB flash drive]]s, [[SD card]]s, [[MultiMediaCard]]s (MMC) and [[eMMC]] because of its compatibility across [[cross-platform software|operating systems]] and [[embedded systems]], and ease of implementation.<ref>{{Cite web |title=A brief introduction to FAT (File Allocation Table) formats |url=http://www.wizcode.com/articles/comments/a-brief-introduction-to-fat-file-allocation-table/ |url-status=dead |archive-url=https://web.archive.org/web/20150925082826/http://www.wizcode.com/articles/comments/a-brief-introduction-to-fat-file-allocation-table/ |archive-date=September 25, 2015 |access-date=2015-09-24 |website=www.wizcode.com |df=mdy-all}}</ref>

== Uses ==
<span id="ECMA"></span><span id="ISO"></span>

=== Historical ===
FAT was used on [[hard disk drive|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 [[Microsoft Windows|Windows]] to use FAT as its default file system.

For floppy disks, FAT has been standardized as [[Ecma International|ECMA]]-107<ref name="Ecma-107" /> and [[International Organization for Standardization|ISO]]/[[International Electrotechnical Commission|IEC]]&nbsp;9293:1994<ref name="ISO_9293_1994" /> (superseding ISO&nbsp;9293:1987<ref name="ISO_9293_1987" />). These standards cover FAT12 and FAT16 with only short [[8.3 filename]] support; [[long filename]]s with [[#VFAT|VFAT]] were partially [[#Patents|patent]]ed.<ref name="Patent_5758352" /> While [[#FAT12|FAT12]] is used on floppy disks, [[#FAT16|FAT16]] and [[#FAT32|FAT32]] are typically found on the larger media.

=== Modern ===
FAT is used internally for the [[EFI system partition]] in the boot stage of [[Extensible Firmware Interface|EFI]]-compliant computers.<ref name="efi" />

FAT is still used in drives expected to be used by multiple operating systems, such as in shared Windows and [[Linux]] environments. Microsoft Windows additionally comes with a pre-installed tool to convert a FAT file system into NTFS directly without the need to rewrite all files, though this cannot be reversed easily.<ref>{{cite web |date=11 July 2021 |title=How to Convert a Drive from FAT32 to NTFS without Data Loss |url=https://windowsloop.com/how-to-convert-a-drive-from-fat32-to-ntfs-without-data-loss/ |url-status=live |archive-url=https://web.archive.org/web/20210808233345/https://windowsloop.com/how-to-convert-a-drive-from-fat32-to-ntfs-without-data-loss/ |archive-date=2021-08-08 |access-date=8 August 2021 |website=WindowsLoop |language=en-us}}</ref> 

The FAT file system is used in removable media such as [[floppy disk]]s, [[superfloppy|super-floppies]], [[memory card|memory]] and [[flash memory]] cards or [[USB flash drives]]. FAT is supported by portable devices such as [[Personal digital assistant|PDA]]s, [[digital camera]]s, [[camcorder]]s, [[Portable media player|media player]]s, mobile phones, [[game console]]s, as well as [[embedded system]]s such as [[boombox]]es and [[DVD player]]s and [[vehicle audio]] systems with built-in [[USB]] ports and [[SD card]] readers.<ref>{{cite web |url=https://blinksandbuttons.net/what-format-does-a-usb-need-to-be-for-a-dvd-player/ |title=What Format Does a USB Need to Be for a DVD Player? Simplifying Compatibility Requirements |date=2024-08-01 |access-date=2025-09-04 |author=James Ellison |website=Blinks and Buttons }}</ref><ref>{{cite web |url=https://www.pcmag.com/how-to/fat32-vs-exfat-vs-ntfs-which-format-is-best-for-your-storage-drive |title=FAT32 vs. ExFAT vs. NTFS: Which Format Is Best for Your Storage Drive? |author=John Bogna |website=PCMag |date=23 July 2024 |access-date=2025-09-04 }}</ref>

The [[Design rule for Camera File system|DCF]] file system adopted by almost all [[digital camera]]s since 1998 defines a logical file system with [[8.3 filename]]s and makes the use of either FAT12, FAT16, FAT32 or exFAT mandatory for its physical layer for compatibility.<ref name="DC-009-2010" />

== Technical details ==
<span id="Technical design"></span><!-- N.B.: Parked formerly used anchors here to maintain link integrity for as long as not all incoming links have been fixed up to point to [[Design of the FAT file system]] instead. -->
{{anchor|Layout|RSVD_SECTORS|DATA_AREA}}
{{anchor|Boot Sector|Bootsector|BSIBM_OFS_000h|BSIBM_OFS_003h|BSIBM_OFS_1FDh|BSIBM_OFS_1FEh|BSST_OFS_000h|BSST_OFS_002h|BSST_OFS_008h|BSST_OFS_1FEh}}
{{anchor|BSMSX_OFS_000h|BSMSX_OFS_003h|BSMSX_OFS_01Eh|BSMSX_OFS_020h|BSMSX_OFS_026h|BSMSX_OFS_027h|BSMSX_OFS_02Bh|BSMSX_OFS_030h|BSMSX_OFS_1FEh}}
{{anchor|BIOS Parameter Block|BPB|BPB20|BPB20_OFS_00h|BPB20_OFS_02h|BPB20_OFS_03h|BPB20_OFS_05h|BPB20_OFS_06h|BPB20_OFS_08h|BPB20_OFS_0Ah}}
{{anchor|media|BPB20_OFS_0Bh|BPB30|BPB30_OFS_0Dh|BPB30_OFS_0Fh|BPB30_OFS_11h|BPB32|BPB32_OFS_13h|BPB331|BPB331_OFS_0Dh}}
{{anchor|BPB331_OFS_0Fh|BPB331_OFS_11h|BPB331_OFS_15h}}
{{anchor|Extended BIOS Parameter Block|EBPB|EBPB_OFS_19h|EBPB_OFS_1Ah|EBPB_OFS_1Bh|EBPB_OFS_1Ch|EBPB_OFS_20h|EBPB_OFS_2Bh}}
{{anchor|FAT32 Extended BIOS Parameter Block|EBPB32|EBPB32_OFS_19h|EBPB32_OFS_1Dh|EBPB32_OFS_1Fh|EBPB32_OFS_21h|EBPB32_OFS_25h|EBPB32_OFS_27h|EBPB32_OFS_29h|EBPB32_OFS_35h}}
{{anchor|EBPB32_OFS_36h|EBPB32_OFS_37h|EBPB32_OFS_38h|EBPB32_OFS_3Ch|EBPB32_OFS_47h}}
{{anchor|Exceptions|FATID|FS Information Sector|File Allocation Table|CLUST_0|CLUST_1|BAD_CLUST|FAT_EOC}}
{{anchor|Directory table|DIR|Directory entry|DIR_OFS_00h|DIR_OFS_08h|DIR_OFS_0Bh|attributes|DIR_OFS_0Ch|DIR_OFS_0Dh|DIR_OFS_0Eh}}
{{anchor|Format_Time|DIR_OFS_10h|Format_Date|DIR_OFS_12h|DIR_OFS_14h|access rights|DIR_OFS_16h|DIR_OFS_18h|DIR_OFS_1Ah|DIR_OFS_1Ch}}
{{anchor|VFAT long file names|VFAT_OFS_00h|VFAT_OFS_01h|VFAT_OFS_0Bh|VFAT_OFS_0Ch|VFAT_OFS_0Dh|VFAT_OFS_0Eh|VFAT_OFS_1Ah|VFAT_OFS_1Ch|Size limits|Fragmentation}}
{{Main|Design of the FAT file system}}
The file system uses an index table stored on the device to identify chains of data storage areas associated with a file, the ''[[Design of the FAT file system#FAT|File Allocation Table]]'' (''FAT''). The FAT is statically allocated at the time of formatting. The table is a [[linked list]] of entries for each ''[[cluster (file system)|cluster]]'', a contiguous area of disk storage. Each entry contains either the number of the next cluster in the file, or else a marker indicating the end of the file, unused disk space, or special reserved areas of the disk. The ''root directory'' of the disk contains the number of the first cluster of each file in that directory. The operating system can then traverse the FAT, looking up the cluster number of each successive part of the disk file as a ''cluster chain'' until the end of the file is reached. ''Sub-directories'' are implemented as special files containing the ''directory entries'' of their respective files.

Each entry in the FAT linked list is a fixed number of bits: 12, 16 or 32. The maximum size of a file or a disk drive that can be accessed is the product of the largest number that can be stored in the entries (less a few values reserved to indicate unallocated space or the end of a list) and the size of the disk cluster. Even if only one byte of storage is needed to extend a file, an entire cluster must be allocated to it. As a result, large numbers of small files can result in clusters being allocated that may contain mostly "empty" data to meet the minimum cluster size.

Originally designed as an 8-bit file system, the maximum number of clusters must increase as disk drive capacity increases, and so the number of bits used to identify each cluster has grown. The successive major variants of the FAT format are named after the number of table element bits: 12 ([[#FAT12|FAT12]]), 16 ([[#FAT16|FAT16]]), and 32 ([[#FAT32|FAT32]]).

== Variants ==
There are several variants of the FAT file system (e.g. [[#FAT12|FAT12]], [[#FAT16|FAT16]] and [[#FAT32|FAT32]]). FAT16 refers to both the original group of FAT file systems with 16-bit wide cluster entries and also to later variants. "[[#VFAT|VFAT]]" is an optional extension for long file names, which can work on top of any FAT file system. Volumes using  VFAT long-filenames can be read also by operating systems not supporting the VFAT extension.

=== <span id="FAT8"></span><span id="FAT10"></span>Original 8-bit FAT ===
<!-- NB. "FAT8" and "FAT10" are used as handy invisible anchors, but they never were the official names for these FAT variants, and therefore must not be used in the visible text. -->
{{infobox file system
| name = 8-bit FAT
| full_name = 8-bit File Allocation Table
| developer = [[Microsoft]], [[NCR Corporation|NCR]], [[Seattle Computer Products|SCP]]
| variants = 
| introduction_date = {{ubli
 | 1977/1978: [[NCR Basic +6]] for NCR
 | 1978: [[Standalone Disk BASIC-80]] (16-byte directory entries)<ref name="Microsoft_1979_BASIC80-50" /><ref name="Microsoft_1979_BASIC80-51" />
 | (1978: [[Standalone Disk BASIC-86]] internal only)
 | 1979-06-04: [[Standalone Disk BASIC-86]] for SCP (16-byte directory entries)
 | 1979: [[MIDAS (operating system)|MIDAS]] (32-byte directory entries)
 }}
| partition_id = 
| directory_struct = 
| file_struct = 
| bad_blocks_struct = 
| max_volume_size = <!-- TBD -->
| max_file_size = 8 MB
| max_files_no = <!-- TBD -->
| max_filename_size = [[6.3 filename]]<!-- displayed with decimal dot as "123456.789" --> (binary files), 9&nbsp;characters<!-- displayed with space as "123456 789" --> (ASCII files)<ref name="Microsoft_1979_BASIC80-50" /><ref name="Microsoft_1979_BASIC80-51" />
| max_directory_depth = No sub-directories
| dates_recorded = No
| forks_streams = 
| attributes = Write protected, [[EBCDIC]] conversion, read after write, binary (random rather than sequential file)<ref name="Microsoft_1979_BASIC80-50" /><ref name="Microsoft_1979_BASIC80-51" />
| file_system_permissions = 
| compression = 
| encryption = 
| data_deduplication = 
| OS = 
| filename_character_set = [[ASCII]] (<code>0x00</code> and <code>0xFF</code> not allowed in first character)<ref name="Microsoft_1979_BASIC80-50" /><ref name="Microsoft_1979_BASIC80-51" /><!-- In reality, character set is most probably more limited due to BASIC language restrictions. -->
| file_size_granularity = record-granularity (128&nbsp;bytes<!-- 256 bytes for mini-disks? -->)<ref name="Microsoft_1979_BASIC80-50" /><ref name="Microsoft_1979_BASIC80-51" />
}}
The original FAT file system (or ''FAT structure'', as it was called initially) was designed and implemented by [[Marc McDonald]],<ref name="Duncan_1988_MS-DOS_Encyclopedia" /> based on a series of discussions between McDonald and [[Bill Gates]].<ref name="Duncan_1988_MS-DOS_Encyclopedia" />
It was introduced with [[8-bit]] table elements<ref name="Microsoft_1979_BASIC80-50" /><ref name="Microsoft_1979_BASIC80-51" /><ref name="Duncan_1988_MS-DOS_Encyclopedia" /> (and valid data cluster numbers up to <code>0xBF</code><ref name="Microsoft_1979_BASIC80-50" /><ref name="Microsoft_1979_BASIC80-51" />) in a precursor to [[Microsoft]]'s ''[[Standalone Disk BASIC-80]]'' for an [[Intel 8080|8080]]-based successor<ref group="nb" name="NB_NCR_FAT" /> of the [[NCR 7200 model VI]]<!-- model I and IV did not came with BASIC, whereas the still cassette-based model VI did in Q1/1977 --> data-entry terminal, equipped with 8-inch (200&nbsp;mm) floppy disks, in 1977<ref name="Manes_1993_Gates" /> or 1978.<ref group="nb" name="NB_NCR_FAT" />
In 1978, ''Standalone Disk BASIC-80'' was ported to the [[Intel 8086|8086]] using an emulator on a DEC [[PDP-10]],<ref name="Hunter_1983_Softalk" /> since no real 8086 systems were available at this time.
The FAT file system was also used in Microsoft's [[MIDAS (operating system)|MDOS/MIDAS]],<ref name="Duncan_1988_MS-DOS_Encyclopedia" /> an [[operating system]] for 8080/Z80 platforms written by McDonald since 1979.
The ''Standalone Disk BASIC'' version supported three FATs,<ref name="Microsoft_1979_BASIC80-50" /><ref name="Microsoft_1979_BASIC80-51" /><ref name="Schulman_1994_Undocumented-DOS" /> whereas this was a parameter for MIDAS. Reportedly, MIDAS was also prepared to support 10-bit, 12-bit and 16-bit FAT variants. While the size of directory entries was 16 bytes in ''Standalone Disk BASIC'',<ref name="Microsoft_1979_BASIC80-50" /><ref name="Microsoft_1979_BASIC80-51" /> MIDAS instead occupied 32&nbsp;bytes per entry.

[[Tim Paterson]] of [[Seattle Computer Products]] (SCP) was first introduced to Microsoft's FAT structure when he helped [[Bob O'Rear]] adapting the ''[[Standalone Disk BASIC-86]]'' emulator port onto SCP's [[S-100 bus]] 8086 [[Central processing unit|CPU]] board prototype during a guest week at Microsoft in May 1979.<ref name="Hunter_1983_Softalk" /> The final product was shown at [[Lifeboat Associates]]' booth stand at the [[National Computer Conference]] in New York<ref name="Hunter_1983_Softalk" /> on June 4–7, 1979, where Paterson learned about the more sophisticated FAT implementation in MDOS/MIDAS<ref name="Duncan_1988_MS-DOS_Encyclopedia" /> and McDonald talked to him about the design of the file system.<ref name="Manes_1993_Gates" />

=== FAT12 ===
<!-- NB. The header "FAT12" is used in redirects to this page. -->
{{infobox file system
| name                    = FAT12
| developer               = [[Seattle Computer Products|SCP]], [[Microsoft]], [[IBM]], [[Digital Research]], [[Novell]]
| full_name               = [[Design of the FAT file system#FAT12|12-bit File Allocation Table]]
| introduction_date       = {{ubli
 | 1980-07 ([[QDOS 0.10]], 16-byte directory entries)
 | 1981-02-25 ([[86-DOS 0.42]], 32-byte [[FAT directory entry|directory entries]], several reserved sectors)
 | c. 1981–08/10 ([[PC DOS 1.0]], 32-byte directory entries, 1&nbsp;reserved sector)
 | 1982-03-03 ([[MS-DOS 1.25]], 32-byte directory entries, 1&nbsp;reserved sector)
 }}
| partition_id            = [[Master Boot Record|MBR]]/[[Extended Boot Record|EBR]]:{{ubli
 | [[#FAT12|FAT12]]: <code>{{abbr|0x|Values in C-notation for hexadecimal numbers}}[[Partition type#PID 01h|01]]</code> e.a.
 | [[Basic data partition|BDP]]: <code>EBD0A0A2-B9E5-4433-87C0-68B6B72699C7</code>
 }}
| max_volume_size         = {{ubli
 | 16&nbsp;MB (with 4&nbsp;KB clusters)
 | 32&nbsp;MB (with 8&nbsp;KB clusters)<!-- larger volumes should use logical sectored FAT partition IDs or FAT16 partition IDs -->
 }}
| max_file_size           = Limited by volume size
| file_size_granularity   = 1&nbsp;byte
| max_files_no            = 4,068 for 8&nbsp;KB clusters<!-- 2^12 - 12 (reserved clusters) - 16 (number of 8&nbsp;KB clusters for directory entries) -->
| max_filename_size       = [[8.3 filename]] with [[OEM character set|OEM]] characters, <br />255 [[UCS-2]] characters<ref group="nb" name="NB_LFN_UNI"/> when using [[Long filename|LFN]]
| max_directory_depth     = 32&nbsp;levels or 66&nbsp;characters (with [[Current Directory Structure|CDS]]), <br />60&nbsp;levels or more (without CDS)
| dates_recorded          = {{ubli
 | Modified date (not with 86-DOS before 0.42),
 | modified time (not with PC&nbsp;DOS 1.0 and 86-DOS), creation date/time (DOS 7.0 and higher only),
 | access date (only available with [[ACCDATE (CONFIG.SYS directive)|ACCDATE]] enabled),<ref name="Microsoft_2006_ACCDATE" />
 | deletion date/time (only with DELWATCH 2<!-- with Novell DOS 7, Caldera OpenDOS 7.01, DR-DOS 7.02 and higher -->)
 }}
| date_range              = [[Epoch of 1980-01-01|1980-01-01]] to [[Year 2100 problem|2099-12-31]] ([[Year 2108 problem|2107-12-31]])
| date_resolution         = {{ubli
 | 2&nbsp;seconds for last modified time,
 | 10&nbsp;ms for creation time,
 | 1&nbsp;day for access date,
 | 2&nbsp;seconds for deletion time
 }}
| attributes              = [[FAT file attributes|Read-only]] (since DOS&nbsp;2.0), [[FAT file attributes|hidden]], [[FAT file attributes|system]], [[FAT file attributes|volume]] (since [[MS-DOS 1.28]] and [[PC DOS 2.0]]), [[FAT file attributes|directory]] (since [[MS-DOS 1.40]] and PC&nbsp;DOS&nbsp;2.0), [[FAT file attributes|archive]] (since DOS&nbsp;2.0)
| file_system_permissions = {{ubli
 | File, directory and volume access rights for [[FAT file access rights|read]], [[FAT file access rights|write]], [[FAT file access rights|execute]], [[FAT file access rights|delete]] only with [[DR-DOS]], [[PalmDOS]], [[Novell DOS]], [[OpenDOS]], [[FlexOS]], [[IBM 4680 OS|4680&nbsp;OS]], [[IBM 4690 OS|4690&nbsp;OS]], [[Concurrent DOS]], [[Multiuser DOS]], [[Datapac System Manager|System Manager]], [[REAL/32]]:{{ubli
  | execute right only with FlexOS, 4680&nbsp;OS, 4690&nbsp;OS; individual file / directory passwords not with FlexOS, 4680&nbsp;OS, 4690&nbsp;OS<!-- at least I could not find any user or programmer's documentation for it so far -->;
  | [[FAT file access rights|world]]/[[FAT file access rights|group]]/[[FAT file access rights|owner]] permission classes only with multiuser security loaded
  }}
 }}
| compression             = Per-volume, [[SuperStor]], [[Stacker (disk compression)|Stacker]], [[DoubleSpace]], [[DriveSpace]]
| encryption              = Per-volume only with [[DR-DOS]]
}}
Between April and August 1980, while borrowing the FAT concept for SCP's own 8086 operating system [[QDOS 0.10]],<ref name="Hunter_1983_Softalk" /> Tim Paterson extended the table elements to '''12 bits''',<ref name="Paterson_2007_Design-DOS" /> reduced the number of FATs to two, redefined the semantics of some of the reserved cluster values, and modified the disk layout, so that the root directory was now located between the FAT and the data area for his implementation of '''FAT12'''. Paterson also increased the nine-character (6.3) filename<ref name="Microsoft_1979_BASIC80-50" /><ref name="Microsoft_1979_BASIC80-51" /> length limit to eleven characters to support [[CP/M]]-style [[8.3 filename]]s and [[File Control Block]]s. The format used in Microsoft ''Standalone Disk BASIC's'' 8-bit file system precursor was not supported by QDOS. By August 1980, QDOS had been renamed to [[86-DOS]].<ref name="BYTE_1980_86-DOS" /> Starting with [[86-DOS 0.42]], the size and layout of directory entries was changed from 16&nbsp;bytes to 32&nbsp;bytes<ref name="SCP_1981_86-DOS_1.0_Addendum" /> in order to add a file date stamp<ref name="SCP_1981_86-DOS_1.0_Addendum" /> and increase the theoretical file size limit beyond the previous limit of 16&nbsp;MB.<ref name="SCP_1981_86-DOS_1.0_Addendum" />
[[86-DOS 1.00]] became available in early 1981. Later in 1981, 86-DOS evolved into Microsoft's [[MS-DOS]] and [[IBM]] [[PC DOS]].<ref name="Duncan_1988_MS-DOS_Encyclopedia" /><ref name="Paterson_2007_Design-DOS" /><ref name="Wallace_1992_Harddrive" />
The capability to read previously formatted volumes with 16-byte directory entries<ref name="SCP_1981_86-DOS_1.0_Addendum" /> was dropped with [[MS-DOS 1.20]].

FAT12 used 12-bit entries for the cluster addresses; some values were reserved to mark the end of a chain of clusters, to mark unusable areas of the disk, or for other purposes, so the maximum number of clusters was limited to 4078.<ref name="Norton2" /><ref name="Jenkinson_2000_Forensic" /> To conserve disk space, two 12-bit FAT entries used three consecutive 8-bit bytes on disk, requiring manipulation to unpack the 12-bit values. This was sufficient for the original floppy disk drives, and small hard disks up to 32 megabytes. The [[#FAT16B|FAT16B]] version available with DOS&nbsp;3.31 supported [[32-bit]] sector numbers, and so increased the volume size limit.

All the control structures fit inside the first track, to avoid head movement during read and write operations. Any bad sector in the control structures area would make the disk unusable. The DOS formatting tool rejected such disks completely. Bad sectors were allowed only in the file data area. Clusters containing bad sectors were marked unusable with the reserved value <code>0xFF7</code> in the FAT.

While 86-DOS supported three disk formats (250.25&nbsp;KB, 616&nbsp;KB and 1232&nbsp;KB, with [[FAT ID]]s <code>0xFF</code> and <code>0xFE</code>) on 8-inch (200&nbsp;mm) floppy drives, IBM [[PC&nbsp;DOS 1.0]], released with the original [[IBM Personal Computer]] in 1981, supported only an 8-sector floppy format with a formatted capacity of 160&nbsp;KB (FAT ID <code>0xFE</code>) for single-sided 5.25-inch floppy drives, and [[PC&nbsp;DOS 1.1]] added support for a [[double-sided disk|double-sided]] format with 320&nbsp;KB (FAT ID <code>0xFF</code>). [[PC DOS 2.0]] introduced support for 9-sector floppy formats with 180&nbsp;KB (FAT ID <code>0xFC</code>) and 360&nbsp;KB (FAT ID <code>0xFD</code>).

86-DOS&nbsp;1.00 and PC&nbsp;DOS 1.0 directory entries included only one date, the last modified date. PC&nbsp;DOS 1.1 added the last modified time. PC&nbsp;DOS 1.x [[file attribute]]s included a hidden bit and system bit, with the remaining six bits undefined. At this time, DOS did not support sub-directories, but typically there were only a few dozen files on a [[floppy disk|diskette]].

The [[PC XT]] was the first PC with an IBM-supplied hard drive, and PC&nbsp;DOS 2.0 supported that hard drive with FAT12 ([[FAT ID]] <code>0xF8</code>). The fixed assumption of 8&nbsp;sectors per clusters on hard disks practically limited the maximum partition size to 16&nbsp;MB for 512&nbsp;byte sectors and 4&nbsp;KB clusters.

The ''[[BIOS Parameter Block]]'' (''BPB'') was introduced with PC&nbsp;DOS&nbsp;2.0 as well, and this version also added read-only, [[archive bit|archive]], [[volume (computing)|volume label]], and [[Directory (file systems)|directory]] attribute bits for hierarchical sub-directories.<ref name="two" />

[[MS-DOS 3.0]] introduced support for high-density 1.2&nbsp;MB 5.25-inch diskettes (media descriptor <code>0xF9</code>), which notably had 15&nbsp;sectors per track, hence more space for the FATs.

FAT12 remains in use on all common [[floppy disks]], including 1.44&nbsp;MB and later 2.88&nbsp;MB disks (media descriptor byte <code>0xF0</code>).

=== <span id="FAT16"></span>Initial FAT16 ===

{{infobox file system
| name                    = FAT16
| developer               = [[Microsoft]], [[IBM]], [[Digital Research]], [[Novell]]
| full_name               = [[Design of the FAT file system#FAT16|16-bit File Allocation Table]]<br />(with 16-bit sector entries)
| introduction_date       = 1984-08-14 (PC DOS 3.0)<br />1984-08 (MS-DOS 3.0)
| partition_id            = [[Master Boot Record|MBR]]/[[Extended Boot Record|EBR]]:{{ubli
 | [[#FAT16|FAT16]]:&nbsp;<code>{{abbr|0x|Values in C-notation for hexadecimal numbers}}[[Partition type#PID_04h|04]]</code> e.a.
 | [[Basic data partition|BDP]]: <code>EBD0A0A2-B9E5-4433-87C0-68B6B72699C7</code>
 }}
<!-- needs more refinement as this is version dependent:
| max_volume_size         = 16&nbsp;[[megabyte|MB]] (with 2&nbsp;KB clusters) --><!-- larger volumes should use logical sectored FAT partition IDs or FAT16B partition ID -->
| max_file_size           = 4,294,967,295 bytes (4&nbsp;GB − 1)<!-- Not "limited by volume size" if volumes larger than 4 GB are possible. -->
| file_size_granularity   = 1&nbsp;byte
| max_files_no            = 65,536 for 32&nbsp;KB clusters<!-- 2^16 − 12 (reserved clusters) − 64 (number of 32 KB clusters for directory entries) -->
| max_filename_size       = [[8.3 filename]] with [[OEM character set|OEM]] characters, 255&nbsp;[[UCS-2]] characters<ref group="nb" name="NB_LFN_UNI"/> when using [[Long filename|LFN]]
| max_directory_depth     = 32&nbsp;levels or 66&nbsp;characters (with [[Current Directory Structure|CDS]]), <br />60&nbsp;levels or more (without CDS)
| dates_recorded          = {{ubli
 | Modified date/time, creation date/time (DOS 7.0 and higher only),
 | access date (only available with [[ACCDATE (CONFIG.SYS directive)|ACCDATE]] enabled),<ref name="Microsoft_2006_ACCDATE" />
 | deletion date/time (only with DELWATCH 2<!-- with Novell DOS 7, Caldera OpenDOS 7.01, DR-DOS 7.02 and higher -->)
 }}
| date_range              = [[Epoch of 1980-01-01|1980-01-01]] to [[Year 2100 problem|2099-12-31]] ([[Year 2108 problem|2107-12-31]])
| date_resolution         = {{ubli
 | 2&nbsp;seconds for last modified time,
 | 10&nbsp;ms for creation time,
 | 1&nbsp;day for access date,
 | 2&nbsp;seconds for deletion time
 }}
| attributes              = [[FAT file attributes|Read-only]], [[FAT file attributes|hidden]], [[FAT file attributes|system]], [[FAT file attributes|volume]], [[FAT file attributes|directory]], [[FAT file attributes|archive]]
| file_system_permissions = {{ubli
 | File, directory and volume access rights for [[FAT file access rights|read]], [[FAT file access rights|write]], [[FAT file access rights|execute]], [[FAT file access rights|delete]] only with [[DR-DOS]], [[PalmDOS]], [[Novell DOS]], [[OpenDOS]], [[FlexOS]], [[IBM 4680 OS|4680&nbsp;OS]], [[IBM 4690 OS|4690&nbsp;OS]], [[Concurrent DOS]], [[Multiuser DOS]], [[Datapac System Manager|System Manager]], [[REAL/32]]:{{ubli
  | execute right only with FlexOS, 4680&nbsp;OS, 4690&nbsp;OS;
  | individual file / directory passwords not with FlexOS, 4680&nbsp;OS, 4690&nbsp;OS<!-- at least I could not find any user or programmer's documentation for it so far -->;
  | [[FAT file access rights|world]]/[[FAT file access rights|group]]/[[FAT file access rights|owner]] permission classes only with multiuser security loaded
  }}
 }}
| compression             = Per-volume, [[SuperStor]], [[Stacker (disk compression)|Stacker]], [[DoubleSpace]], [[DriveSpace]]
| encryption              = Per-volume only with [[DR-DOS]]
}}
In 1984, IBM released the [[PC AT]], which required PC&nbsp;DOS&nbsp;3.0 to access its 20&nbsp;MB hard disk.<ref name="IBM_1984_PCDOS30" /><ref name="IBM_1985_Reference" /> Microsoft introduced MS-DOS&nbsp;3.0 in parallel. Cluster addresses were increased to 16-bit, allowing for up to 65,526&nbsp;clusters per volume. However, the maximum possible number of sectors and the maximum [[Disk partitioning|partition]] size of 32&nbsp;MB did not change. Although cluster addresses were 16&nbsp;bits, this format was not what today is commonly understood as '''FAT16'''.
A [[partition type]] <code>[[Partition type#PID_04h|0x04]]</code> indicates this form of FAT16 with less than 65,536&nbsp;sectors (less than 32&nbsp;MB for sector size 512). The benefit of FAT16 was the use of smaller clusters, making disk usage more efficient, particularly for large numbers of files only a few hundred bytes in size.

As MS-DOS&nbsp;3.0 formatted all 16&nbsp;MB-32&nbsp;MB partitions in the FAT16 format, a 20&nbsp;MB hard disk formatted under MS-DOS&nbsp;3.0 was not accessible by MS-DOS&nbsp;2.0.<ref name="Microsoft_69912">{{Cite web |url=http://c-bit.org/kb/69912/EN-US/ |title=Microsoft Knowledge Base article: "MS-DOS Partitioning Summary" |access-date=2018-06-02  |archive-date=2018-06-12  |archive-url=https://web.archive.org/web/20180612143554/http://c-bit.org/kb/69912/EN-US/ |url-status=live }}</ref> MS-DOS&nbsp;3.0 to MS-DOS&nbsp;3.30 could still access FAT12 partitions under 15&nbsp;MB, but required all 16&nbsp;MB-32&nbsp;MB partitions to be FAT16, and so could not access MS-DOS&nbsp;2.0 partitions in this size range. MS-DOS&nbsp;3.31 and higher could access 16&nbsp;MB-32&nbsp;MB FAT12 partitions again.

=== Logical sectored FAT ===
{{See also|Extended boot record}}
<!-- NB. The header "Logical sectored FAT" is used in redirects to this page. -->

MS-DOS and PC&nbsp;DOS implementations of FAT12 and FAT16 could not access disk partitions larger than 32 megabytes. Several manufacturers developed their own FAT variants within their OEM versions of MS-DOS.<ref name="Novell_1993_FYI.M.1101"/>

Some vendors ([[AST Research|AST]] and [[NEC]]<ref name="Novell_1993_FYI.M.1101"/>) supported [[AST MBR<!-- NEC MBR -->|eight]], instead of the standard [[Partition table (master boot record)|four]], primary partition entries in their custom extended ''[[Master Boot Record]]'' (''MBR''), and they adapted MS-DOS to use more than a single primary partition.

Other vendors worked around the volume size limits imposed by the 16-bit sector entries by increasing the apparent ''size'' of the sectors the file system operated on. These ''logical sectors'' were larger (up to 8192&nbsp;bytes) than the ''physical sector'' size (still 512&nbsp;bytes) on the disk. The DOS-BIOS or System BIOS would then combine multiple physical sectors into logical sectors for the file system to work with.

These changes were transparent to the file system implementation in the DOS kernel. The underlying DOS-BIOS translated these logical sectors into physical sectors according to partitioning information and the drive's physical geometry.

The drawback of this approach was increased memory used for sector buffering and deblocking. Since older DOS versions could not use large logical sectors, the OEMs introduced new partition IDs for their FAT variants in order to hide them from off-the-shelf issues of MS-DOS and PC DOS. Known partition IDs for logical sectored FATs include: <code>[[Partition type#PID_08h|0x08]]</code> ([[Commodore International|Commodore]] MS-DOS 3.x), <code>[[Partition type#PID_11h|0x11]]</code> ([[Leading Edge Hardware Products|Leading Edge]] MS-DOS 3.x), <code>[[Partition type#PID_14h|0x14]]</code> (AST MS-DOS 3.x), <code>[[Partition type#PID_24h|0x24]]</code> (NEC MS-DOS 3.30<ref name="Novell_1993_FYI.M.1101"/>), <code>[[Partition type#PID_56h|0x56]]</code> ([[AT&T Corporation|AT&T]] MS-DOS 3.x), <code>[[Partition type#PID_E5h|0xE5]]</code> ([[Tandy Computers|Tandy]] MS-DOS), <code>[[Partition type#PID_F2h|0xF2]]</code> ([[Sperry Corporation|Sperry IT]] MS-DOS 3.x, [[Unisys]] MS-DOS 3.3 – also used by [[Digital Research]] [[DOS Plus]] 2.1).<ref name="Brouwer_2002_Partition-IDs" /> OEM versions like Toshiba&nbsp;MS-DOS, Wyse&nbsp;MS-DOS&nbsp;3.2<!-- with 1024 bytes/sector --> and 3.3,<ref name="Microsoft_2000_Wyse-DOS" /> as well as Zenith&nbsp;MS-DOS are also known to have utilized logical sectoring.<ref name="Microsoft_2000_Logical-sectoring" /><!-- but partition IDs and other specifics of these formats are not known -->

While non-standard and sub-optimal, these FAT variants are perfectly valid according to the specifications of the file system itself.{{citation needed|date=June 2022}} Therefore, even if default issues of MS-DOS and PC&nbsp;DOS were not able to cope with them, most of these vendor-specific FAT12 and FAT16 variants can be mounted by more flexible file system implementations in operating systems such as DR-DOS, simply by changing the partition ID to one of the recognized types.<ref group="nb" name="NB_DRDOS_Logical-Sectoring">DR-DOS is able to boot off FAT12/FAT16 logical sectored media with [[BPB logical sector size|logical sector size]]s up to 1024 bytes.</ref> Also, if they no longer need to be recognized by their original operating systems, existing partitions can be "converted" into FAT12 and FAT16 volumes more compliant with versions of MS-DOS/PC&nbsp;DOS&nbsp;4.0–6.3, which do not support sector sizes different from 512&nbsp;bytes,<ref name="Brouwer_2002_Logical_FAT" /> by switching to a [[DOS 3.31 BPB|BPB with 32-bit entry]] for the number of sectors, as introduced since DOS&nbsp;3.31 (see [[#FAT16B|FAT16B]] below), keeping the cluster size and reducing the [[BPB logical sector size|logical sector size in the BPB]] down to 512&nbsp;bytes, while at the same time increasing the counts of logical sectors per cluster, reserved logical sectors, total logical sectors, and logical sectors per FAT by the same factor.

A parallel development in MS-DOS / PC&nbsp;DOS which allowed an increase in the maximum possible disk size was the extension of the number of FAT partitions on a hard disk beyond the earlier 4, and the replacement of "installable block devices" with native DOS FAT partitions. To allow the use of more FAT partitions in a compatible way, a new partition type was introduced in PC&nbsp;DOS&nbsp;3.2 (1986), the ''[[Extended boot record|extended partition]]'' (EBR),<ref name="Duncan_1988_MS-DOS_Encyclopedia" /> which is a container for an additional partition called ''logical drive''. Since PC&nbsp;DOS&nbsp;3.3 (April 1987), there is another, optional extended partition containing the next ''logical drive'', and so on. The [[Master Boot Record|MBR]] of a hard disk can either define up to four primary partitions, or an extended partition in addition to up to three primary partitions.

=== <span id="FAT16B"></span><span id="FAT16X"></span>Final FAT16 ===

{{infobox file system
| name                    = FAT16B
| developer               = [[Compaq]], [[Digital Research]], [[IBM]], [[Microsoft]], [[Novell]]
| full_name               = [[Design of the FAT file system#FAT16|16-bit File Allocation Table]]<br />(with 32-bit sector entries)
| introduction_date       = {{ubli
 | 1987-11 ([[Compaq MS-DOS 3.31]])
 | 1988-06-28 ([[DR DOS 3.31]])
 | 1988 ([[IBM DOS 4.0]])
 | 1988 ([[OS/2 1.1]])
 | 1988 ([[MS-DOS 4.0 (IBM-developed)|MS-DOS 4.0]])
 }}
| partition_id            = [[Master Boot Record|MBR]]/[[Extended Boot Record|EBR]]:{{ubli
 | [[#FAT16B|FAT16B]]:&nbsp;<code>{{abbr|0x|Values in C-notation for hexadecimal numbers}}[[Partition type#PID_06h|06]]</code><code>[[Partition type#PID_0Eh|0x0E]]</code> ([[Logical block addressing|LBA]]), e.a.
 | [[Basic data partition|BDP]]: <code>EBD0A0A2-B9E5-4433-87C0-68B6B72699C7</code>
 }}
| min_volume_size         = {{ubli
 | 8&nbsp;[[megabyte|MB]] (with 128&nbsp;byte sectors)
 | 32&nbsp;MB (with [[512e|512]]&nbsp;byte sectors)
 | 256&nbsp;MB (with [[4Kn|4&nbsp;KB]] sectors)
 }}
| max_volume_size         = {{ubli
 | 2&nbsp;[[gigabyte|GB]] (with 32&nbsp;[[kilobyte|KB]] clusters)
 | 4&nbsp;GB (with 64&nbsp;KB clusters) (NT&nbsp;4, PTS-DOS, EDR-DOS)
 | 8&nbsp;GB (with 128&nbsp;KB clusters and <!-- 128 s/c -->1 or <!-- 64 s/c -->2&nbsp;KB sectors) (NT&nbsp;4 and EDR-DOS only)
 | 8&nbsp;GB (with 128&nbsp;KB clusters and <!-- 256 s/c -->512 byte sectors) (EDR-DOS only)
 | 16&nbsp;GB (with 256&nbsp;KB clusters and <!-- 128 s/c -->2 or <!-- 64 s/c -->4&nbsp;KB sectors) (NT&nbsp;4 only)
 }}
| max_file_size           = {{ubli
 | 2,147,483,647 bytes (2&nbsp;GB − 1)<!-- 2^31 − 1 --> (without [[large file support|LFS]])
 | 4,294,967,295 bytes (4&nbsp;GB − 1)<!-- 2^32 − 1 --> (with [[large file support|LFS]])
 | limited by volume size only (with FAT16+<ref name="DRDOS_FAT+_R2" />)
 }}
| file_size_granularity   = 1&nbsp;byte
| max_files_no            = 65,460 for 32&nbsp;KB clusters<!-- 2^16 − 12 (reserved clusters) − 64 (number of 32 KB clusters for directory entries) -->
| max_filename_size       = [[8.3 filename]] with [[OEM character set|OEM]] characters, <br />255 [[UCS-2]] characters<ref group="nb" name="NB_LFN_UNI"/> when using [[Long filename|LFN]]
| max_directory_depth     = 32&nbsp;levels or 66&nbsp;characters (with [[Current Directory Structure|CDS]]), <br />60&nbsp;levels or more (without CDS)
| dates_recorded          = {{ubli
 | Modified date/time, creation date/time (DOS 7.0 and higher only),
 | access date (only available with [[ACCDATE (CONFIG.SYS directive)|ACCDATE]] enabled),<ref name="Microsoft_2006_ACCDATE" />
 | deletion date/time (only with DELWATCH 2<!-- with Novell DOS 7, Caldera OpenDOS 7.01, DR-DOS 7.02 and higher -->)
 }}
| date_range              = [[Epoch of 1980-01-01|1980-01-01]] to [[Year 2100 problem|2099-12-31]] ([[Year 2108 problem|2107-12-31]])
| date_resolution         = {{ubli
 | 2&nbsp;seconds for last modified time,
 | 10&nbsp;ms for creation time,
 | 1&nbsp;day for access date,
 | 2&nbsp;seconds for deletion time
 }}
| attributes              = [[FAT file attributes|Read-only]], [[FAT file attributes|hidden]], [[FAT file attributes|system]], [[FAT file attributes|volume]], [[FAT file attributes|directory]], [[FAT file attributes|archive]]
| file_system_permissions = {{ubli
 | File, directory and volume access rights for [[FAT file access rights|read]], [[FAT file access rights|write]], [[FAT file access rights|execute]], [[FAT file access rights|delete]] only with [[DR-DOS]], [[PalmDOS]], [[Novell DOS]], [[OpenDOS]], [[FlexOS]], [[IBM 4680 OS|4680&nbsp;OS]], [[IBM 4690 OS|4690&nbsp;OS]], [[Concurrent DOS]], [[Multiuser DOS]], [[Datapac System Manager|System Manager]], [[REAL/32]]:{{ubli
  | execute right only with FlexOS, 4680&nbsp;OS, 4690&nbsp;OS;
  | individual file / directory passwords not with FlexOS, 4680&nbsp;OS, 4690&nbsp;OS<!-- at least I could not find any user or programmer's documentation for it so far -->;
  | [[FAT file access rights|world]]/[[FAT file access rights|group]]/[[FAT file access rights|owner]] permission classes only with multiuser security loaded
  }}
 }}
| compression             = Per-volume, [[SuperStor]], [[Stacker (disk compression)|Stacker]], [[DoubleSpace]], [[DriveSpace]]
| encryption              = Per-volume only with [[DR-DOS]]
}}
In November 1987, [[Compaq MS-DOS 3.31|Compaq Personal Computer DOS 3.31]] (a modified OEM version of MS-DOS&nbsp;3.3 released by Compaq with their machines) introduced what today is simply known as ''the FAT16'' format, with the expansion of the 16-bit disk sector count to 32&nbsp;bits in the BPB.
Although the on-disk changes were minor, the entire DOS disk driver had to be converted to use 32-bit sector numbers, a task complicated by the fact that it was written in 16-bit [[x86 assembly language|assembly language]].
The result was initially called the ''DOS 3.31 Large File System''. [[Microsoft]]'s <code>[[DSKPROBE]]</code> tool refers to type <code>[[Partition type#PID_06h|0x06]]</code> as ''BigFAT'',<ref name="Microsoft_2003_CC736327" /> whereas some older versions of <code>[[FDISK]]</code> described it as ''BIGDOS''. Technically, it is known as '''FAT16B'''.

Since older versions of DOS were not designed to cope with more than 65,535&nbsp;sectors, it was necessary to introduce a new partition type for this format in order to hide it from pre-3.31 issues of DOS. The original form of FAT16 (with less than 65,536 sectors) had a [[partition type]] <code>[[Partition type#PID_04h|0x04]]</code>. To deal with disks larger than this, type <code>[[Partition type#PID_06h|0x06]]</code> was introduced to indicate 65,536 or more sectors. In addition to this, the disk driver was expanded to cope with more than 65,535&nbsp;sectors as well. The only other difference between the original FAT16 and the newer FAT16B format is the usage of a [[DOS 3.31 BPB|newer BPB]] format with 32-bit sector entry. Therefore, newer operating systems supporting the FAT16B format can cope also with the original FAT16 format without any necessary changes.

If partitions to be used by pre-DOS&nbsp;3.31 issues of DOS need to be created by modern tools, the only criteria theoretically necessary to meet are a sector count of less than 65536, and the usage of the old partition ID (<code>[[Partition type#PID_04h|0x04]]</code>). In practice however, type <code>[[Partition type#PID_01h|0x01]]</code> and <code>[[Partition type#PID_04h|0x04]]</code> primary partitions should not be physically located outside the first 32&nbsp;MB of the disk, due to other restrictions in MS-DOS&nbsp;2.x, which could not cope with them otherwise.

In 1988, the FAT16B improvement became more generally available through [[DR&nbsp;DOS]]&nbsp;3.31, PC&nbsp;DOS&nbsp;4.0, [[OS/2]]&nbsp;1.1, and MS-DOS&nbsp;4.0. The limit on partition size was dictated by the 8-bit [[Signedness|signed]] count of sectors per cluster, which originally had a maximum power-of-two value of 64. With the standard hard disk sector size of 512&nbsp;bytes, this gives a maximum of 32&nbsp;KB cluster size, thereby fixing the "definitive" limit for the FAT16 partition size at 2&nbsp;GB for sector size 512. On [[magneto-optical]] media, which can have 1 or 2&nbsp;KB sectors instead of 0.5&nbsp;KB, this size limit is proportionally larger.

Much later, [[Windows&nbsp;NT]] increased the maximum cluster size to 64&nbsp;KB, by considering the sectors-per-cluster count as unsigned. However, the resulting format was not compatible with any other FAT implementation of the time, and it generated greater [[internal fragmentation]]. [[Windows 98]], SE and ME also supported reading and writing this variant, but its disk utilities did not work with it and some [[File control block|FCB]] services are not available for such volumes. This contributes to a confusing compatibility situation.

Prior to 1995, versions of DOS accessed the disk via [[Cylinder-head-sector|CHS]] addressing only. When [[Windows&nbsp;95]] (MS-DOS 7.0) introduced [[Logical block addressing|LBA]] disk access, partitions could start being physically located outside the first c. 8&nbsp;GB<!-- exact value is somewhat smaller --> of this disk and thereby out of the reach of the traditional CHS addressing scheme. Partitions partially or fully located beyond the CHS barrier therefore had to be hidden from non-LBA-enabled operating systems by using the new partition type <code>[[Partition type#PID_0Eh|0x0E]]</code> in the partition table instead. FAT16 partitions using this partition type are also named '''FAT16X'''.<ref name="Microsoft_2004_KB120138" /> The only difference, compared to previous FAT16 partitions, is the fact that some CHS-related geometry entries in the BPB record, namely the number of sectors per track and the number of heads, may contain no or misleading values and should not be used.

The number of root directory entries available for FAT12 and FAT16 is determined when the volume is formatted, and is stored in a 16-bit field. For a given number <code>RDE</code> and sector size <code>SS</code>, the number <code>RDS</code> of root directory sectors is <code>RDS = ceil((RDE × 32) / SS)</code>, and <code>RDE</code> is normally chosen to fill these sectors, i.e., <code>RDE × 32 = RDS × SS</code>. FAT12 and FAT16 media typically use 512 root directory entries on non-floppy media. Some third-party tools, like mkdosfs, allow the user to set this parameter.<ref name="MKDOSFS" />

===FAT32===
{{Infobox file system
| name                    = FAT32
| full_name             DEVICE1

[[Design of the FAT file system#FAT32|32-bit File Allocation Table]]<br />(with 28-bit cluster entries)
| developer               = [[Microsoft]], [[Caldera UK|Caldera]]
| variants = 
| introduction_date       = August 1996 ([[Windows 95 OSR2]])
| partition_id            = [[Master Boot Record|MBR]]/[[Extended Boot Record|EBR]]: {{ubli
 | [[#FAT32|FAT32]]: <code>{{abbr|0x|Values in C-notation for hexadecimal numbers}}[[Partition type#PID_0Bh|0B]]</code><code>[[Partition type#PID_0Ch|0x0C]]</code> ([[Logical block addressing|LBA]]), e.a.
 | [[Basic data partition|BDP]]: <code>EBD0A0A2-B9E5-4433-87C0-68B6B72699C7</code>
 }}
| directory_struct = 
| file_struct = 
| bad_blocks_struct = 
| min_volume_size         = {{ubli
 | 32&nbsp;[[megabyte|MB]] – 4.5&nbsp;[[kilobyte|KB]] (with 65525 clusters and 512 byte sectors)
 | 256&nbsp;MB – 36&nbsp;KB (with 65525 clusters and 4&nbsp;[[kilobyte|KB]] sectors)
 }}
| max_volume_size         = {{ubli
 | 2&nbsp;[[terabyte|TB]] (with 512&nbsp;byte sectors)
 | 8&nbsp;TB (with 2&nbsp;KB sectors and 32&nbsp;KB clusters)
 | 16&nbsp;TB (with 4&nbsp;KB sectors and 64&nbsp;KB clusters)
 }}
| max_file_size           = {{ubli
 | 2,147,483,647 bytes (2&nbsp;GiB − 1 byte)<!-- 2^31 - 1 --> (without [[large file support|LFS]])
 | 4,294,967,295 bytes (4&nbsp;GiB − 1 byte)<!-- 2^32 - 1 --><ref name="GB4" /> (with [[large file support|LFS]])
 | 274,877,906,943 bytes (256&nbsp;GiB − 1 byte)<!-- 2^38 - 1 --> (only with FAT32+<ref name="DRDOS_FAT+_R2" />)
 }}
| max_files_no            = 268,173,300 for 32&nbsp;KB clusters<!-- 2^28 − 12 (reserved clusters) − 262144 (number of 32&nbsp;KB clusters for directory entries) -->
| max_filename_size       = [[8.3 filename]] with [[OEM character set|OEM]] characters, <br />255 [[UCS-2]] characters<ref group="nb" name="NB_LFN_UNI"/> when using [[Long filename|LFN]]
| max_directory_depth     = 32&nbsp;levels or 66&nbsp;characters (with [[Current Directory Structure|CDS]]), <br />60&nbsp;levels or more (without CDS)
| dates_recorded          = {{ubli
 | Modified date/time, creation date/time (DOS&nbsp;7.0 and higher only),
 | access date (only available with [[ACCDATE (CONFIG.SYS directive)|ACCDATE]] enabled),<ref name="Microsoft_2006_ACCDATE" />
 | deletion date/time (only with DELWATCH 2<!-- with Novell DOS 7, Caldera OpenDOS 7.01, DR-DOS 7.02 and higher -->)
 }}
| date_range              = [[Epoch of 1980-01-01|1980-01-01]] to [[Year 2100 problem|2099-12-31]] ([[Year 2108 problem|2107-12-31]])
| date_resolution         = {{ubli
 | 2&nbsp;seconds for last modified time,
 | 10&nbsp;ms for creation time,
 | 1&nbsp;day for access date,
 | 2&nbsp;seconds for deletion time
 }}
| forks_streams = 
| attributes              = [[FAT file attributes|Read-only]], [[FAT file attributes|hidden]], [[FAT file attributes|system]], [[FAT file attributes|volume]], [[FAT file attributes|directory]], [[FAT file attributes|archive]]
| file_system_permissions = Partial, only with [[DR-DOS]], [[REAL/32]] and [[4690 OS]]
| compression             = Yes
| encryption              = 
| data_deduplication = 
| OS = 
| file_size_granularity   = 1&nbsp;byte
}}

In order to overcome the volume size limit of FAT16, while at the same time allowing DOS [[Real mode|real-mode]] code to handle the format, Microsoft designed a new version of the file system, '''FAT32''', which supported an increased number of possible clusters, but could reuse most of the existing code, so that the [[conventional memory]] footprint was increased by less than 5&nbsp;KB under DOS.<ref name="Microsoft_1998_CC768180" /> Cluster values are represented by [[32-bit]] numbers, of which 28 bits are used to hold the cluster number.

==== Maximal sizes ====
The FAT32 boot sector uses a 32-bit field for the sector count, limiting the maximal FAT32 volume size to 2&nbsp;[[terabyte]]s with a sector size of 512&nbsp;[[byte]]s. The maximum FAT32 volume size is 16&nbsp;TB with a sector size of 4,096&nbsp;bytes.<ref name="Microsoft_2007_KB184006" /><ref name="Microsoft_2007_KB314463" /> The built-in [[Windows shell]] disk format tool on Windows NT arbitrarily only supports volume sizes up to 32&nbsp;GB,{{refn|group="nb"|This was a decision taken by the developer in question, who assumed his decision would be revised later, something that never happened.<ref>{{cite web | url=https://www.theregister.com/2021/01/04/windows_format_fat32/ | title=Explained: The thinking behind the 32GB Windows Format limit on FAT32 }}</ref>}} but Windows supports reading and writing to preexisting larger FAT32 volumes, and these can be created with the [[command prompt]], [[PowerShell]] or third-party tools,<ref>{{Cite web |last=Glenn |first=Walter |title=How to Format USB Drives Larger Than 32GB With FAT32 on Windows |url=https://www.howtogeek.com/316977/how-to-format-usb-drives-larger-than-32gb-with-fat32-on-windows/ |access-date=2021-01-26 |website=How-To Geek |date=July 20, 2017 |language=en-US |archive-date=2021-01-26  |archive-url=https://web.archive.org/web/20210126003213/https://www.howtogeek.com/316977/how-to-format-usb-drives-larger-than-32gb-with-fat32-on-windows/ |url-status=live }}</ref> or by formatting the volume on a non-Windows system or on a Windows 9x system with FAT32 support and then transferring it to the Windows NT system. In August 2024, Microsoft released an update to Windows 11 preview builds that allows for the creation of FAT32 partitions up to 2TB in size.<ref>{{Cite web |author1=Roshan Ashraf Shaikh |date=2024-08-16 |title=Windows 11 preview build sees FAT32 partition size increased to 2TB after 30 years |url=https://www.tomshardware.com/software/operating-systems/windows-11-preview-build-sees-fat32-partition-size-increased-to-2tb-after-30-years |access-date=2024-08-23 |website=Tom's Hardware |language=en}}</ref> 

The maximal possible size for a file on a FAT32 volume is 4&nbsp;[[gigabyte|GB]] minus 1 byte, or 4,294,967,295 (2<sup>32</sup>&nbsp;−&nbsp;1) bytes. This limit is a consequence of the 4-byte file length entry in the directory table and would also affect relatively huge FAT16 partitions enabled by a sufficient sector size.

Like FAT12 and FAT16, FAT32 does not include direct built-in support for long filenames, but FAT32 volumes can optionally hold [[#VFAT|VFAT]] long filenames in addition to short filenames in exactly the same way as VFAT long filenames have been optionally implemented for FAT12 and FAT16 volumes.

==== Development ====
FAT32 was introduced with [[Windows 95]] OSR2 (MS-DOS 7.1) in 1996, although reformatting was needed to use it, and [[DriveSpace 3]] (the version that came with Windows 95 OSR2 and Windows 98<!-- what about ME? -->) never supported it. [[Windows 98]] introduced a utility to convert existing hard disks from FAT16 to FAT32 without loss of data.

In the Windows NT line, native support for FAT32 arrived in [[Windows 2000]]. A free FAT32 driver for [[Windows NT 4.0]] was available from [[Winternals]], a company later acquired by Microsoft. The acquisition of the driver from official sources is no longer possible. Since 1998, Caldera's dynamically loadable [[DRFAT32]] driver could be used to enable FAT32 support in DR-DOS.<ref name="Caldera_1998_DRFAT32-RM"/><ref name="Caldera_1998_DRFAT32"/> The first version of DR-DOS to natively support FAT32 and LBA access was OEM DR-DOS 7.04 in 1999. That same year [[Intelligent Micro Software|IMS]] introduced native FAT32 support with [[REAL/32]] 7.90, and [[IBM 4690 OS]] added FAT32 support with version 2.<ref name="IBM_4690_User_Guide" /> [[Ahead Software]] provided another dynamically loadable FAT32.EXE driver for DR-DOS 7.03 with [[Nero Burning ROM]] in 2004.<!-- with copyrights 2002-2004 --> IBM introduced native FAT32 support with OEM PC DOS 7.1 in 1999.

Two partition types have been reserved for FAT32 partitions, <code>[[Partition type#PID 0Bh|0x0B]]</code> and <code>[[Partition type#PID 0Ch|0x0C]]</code>. The latter type is also named '''FAT32X''' in order to indicate usage of LBA disk access instead of CHS.<ref name="Caldera_1998_DRFAT32-RM"/><ref name="PowerQuest_1998_PQ4" /><ref name="Livingstone_1998_FAT32X" /><ref name="Duitz_2001_FAQ" /><ref name="Costanzo_1998_FAT32X" /> On such partitions, CHS-related geometry entries, namely the [[MBR partition entry|CHS sector address]]es in the MBR as well as the number of [[BPB sectors per track|sectors per track]] and the [[BPB number of heads|number of heads]] in the EBPB record, may contain no or misleading values and should not be used.<ref name="PowerQuest_1998_FAT32X" /><ref name="Duitz_2001_FAQ" /><ref name="Costanzo_1998_FAT32X" />

== Extensions ==
<!-- === Flash and ROM FAT extensions === for FAT extensions like FTL
=== Secured FAT === for single/multiuser security schemes including those by DRI and Linux
=== Compressed FAT === for compressed and encrypted FAT schemes
=== Deletion tracking === for MSX-DOS, SAVENAME, DELWATCH, SENTRY, UNDELETE, RECYCLE etc.
=== Large file support === for files larger than 2/4 GB, FAT+ etc.
=== Transaction-safe FAT === for TFAT and other transaction safe FAT variants -->

=== <span id="EA"></span>Extended attributes ===

[[OS/2]] heavily depends on [[extended attribute]]s (EAs) and stores them in a hidden file called "<code>EA&#x2420;DATA.&#x2420;SF</code>"<!-- Since the exact spelling is important and most sources list only 10 of the 8+3 available characters in directory entries, recheck the exact 8+3 byte spelling of this filename --> in the [[root directory]] of the [[#FAT12|FAT12]] or [[#FAT16|FAT16]] volume. This file is indexed by two previously reserved bytes in the file's (or directory's) [[FAT directory entry|directory entry]] at offset [[Design of the FAT file system#DIR OFS 14h|<code>0x14</code>]].<ref name="Eager_2000_EA" /> In the [[#FAT32|FAT32]] format, these bytes hold the upper 16&nbsp;bits of the starting cluster number of the file or directory, hence making it impossible to store [[OS/2 EA]]s on FAT32 using this method.

However, the third-party FAT32 [[installable file system]] (IFS) driver FAT32.IFS version 0.70 and higher by Henk Kelder & Netlabs for OS/2, [[eComStation]] and [[ArcaOS]] stores extended attributes in extra files with filenames having the string "<code>&#x2420;EA.&#x2420;SF</code>" appended to the regular filename of the file to which they belong. The driver also utilizes the byte at offset [[Design of the FAT file system#DIR OFS 0Ch|<code>0x0C</code>]] in directory entries to store a special mark byte indicating the presence of extended attributes to help speed up things.<ref name="Kelder_2003_FAT32IFS0913" /><ref name="Kelder_FAT32IFS074" /> (This extension is critically incompatible with the FAT32+ method to store files larger than 4&nbsp;GB minus 1 on FAT32 volumes.)<ref name="DRDOS_FAT+_R2" />

Extended attributes are accessible via the [[Workplace Shell]] desktop, through [[REXX]] scripts, and many system [[graphical user interface|GUI]] and [[command line interface|command-line]] utilities (such as [[4OS2]]).<ref name="Eager_2000_Tavi" />

To accommodate its [[OS/2]] subsystem, [[Windows NT]] supports the handling of extended attributes in [[High Performance File System|HPFS]], [[NTFS]], FAT12 and FAT16. It stores EAs on FAT12, FAT16 and HPFS using exactly the same scheme as OS/2, but does not support any other kind of [[Alternate Data Streams|ADS]] as held on NTFS volumes. Trying to copy a file with any ADS other than EAs from an NTFS volume to a FAT or HPFS volume gives a warning message with the names of the ADSs that will be lost. It does not support the FAT32.IFS method to store EAs on FAT32 volumes.

[[Windows 2000]] onward acts exactly as Windows NT, except that it ignores EAs when copying to FAT32 without any warning (but shows the warning for other ADSs, like "Macintosh Finder Info" and "Macintosh Resource Fork").

[[Cygwin]] uses "<code>EA&#x2420;DATA.&#x2420;SF</code>" files as well.

=== <span id="LFN"></span><span id="VFAT"></span><span id="UVFAT"></span>Long file names ===
<!-- use LFN anchor for generic FAT long filename solutions and VFAT for Microsoft's VFAT -->

One of the [[user experience]] goals for the designers of [[Windows 95]] was the ability to use [[long filename]]s (LFNs—up to 255 [[UCS-2]] [[code unit]]s long),<ref group="nb" name="NB_LFN_UNI"/> in addition to classic [[8.3 filename]]s (SFNs). For [[backward compatibility|backward]] and [[forward compatibility]], LFNs were implemented as an optional extension on top of the existing FAT file system structures using a [[workaround]] in the way directory entries are laid out.

This transparent method to store long file names in the existing FAT file systems without altering their data structures is usually known as [[VFAT long filename|VFAT]] (for "Virtual FAT") after the Windows 95 [[VxD|virtual device driver]].<ref group="nb" name="NB_VFAT_Name" />

Non VFAT-enabled operating systems can still access the files under their short file name alias without restrictions; however, the associated long file names may be lost when files with long filenames are copied under non VFAT-aware operating systems.

In Windows&nbsp;NT, support for VFAT long filenames began with version [[Windows NT 3.5|3.5]].

Linux provides a VFAT filesystem driver to work with FAT volumes with VFAT long filenames. For some time, a [[UVFAT]] driver was available to provide combined support for [[#UMSDOS|UMSDOS]]-style permissions with VFAT long filenames.

[[OS/2]] added long filename support to FAT using [[FAT extended file attributes|extended attributes]] (EA) before the introduction of VFAT. Thus, VFAT long filenames are invisible to OS/2, and EA long filenames are invisible to Windows; therefore, experienced users of both operating systems would have to manually rename the files.

[[Human68K]] supported up to [[18.3 filename]]s and ([[Shift JIS]]) [[Kanji]] characters in a proprietary FAT file system variant.

In order to support [[Java (programming language)|Java]] applications, the [[FlexOS]]-based [[IBM 4690 OS]] version 2 introduced its own [[virtual file system]] (VFS) architecture to store long filenames in the FAT file system in a backwards-compatible fashion. If enabled, the virtual filenames (VFN) are available under separate logical drive letters, whereas the real filenames (RFN) remain available under the original drive letters.<ref name="IBM_4690_Programming_Guide" />

=== Forks and alternate data streams ===
{{Unreferenced section|date=August 2025}}
The FAT file system itself is not designed for supporting [[fork (file system)|alternate data streams]] (ADS), but some operating systems that heavily depend on them have devised various methods for handling them on FAT volumes. Such methods either store the additional information in extra files and directories ([[classic Mac OS]] and [[macOS]]), or give new semantics to previously unused fields of the FAT on-disk data structures ([[OS/2]] and [[Windows NT]]).

Mac&nbsp;OS using [[PC Exchange]] stores its various dates, file attributes and long filenames in a [[hidden file]] called "<code>FINDER.DAT</code>", and [[resource fork]]s (a common Mac&nbsp;OS ADS) in a subdirectory called "<code>RESOURCE.FRK</code>", in every directory where they are used. From PC&nbsp;Exchange&nbsp;2.1 onwards, they store the Mac&nbsp;OS long filenames as standard FAT long filenames and convert FAT filenames longer than 31 characters to unique 31-character filenames, which can then be made visible to Macintosh applications.

[[macOS]] stores [[resource fork]]s and metadata (file attributes, other ADS) using [[AppleDouble format]] in a hidden file with a name constructed from the owner filename prefixed with "<code>._</code>", and [[Finder (software)|Finder]] stores some folder and file metadata in a hidden file called "<code>[[.DS_Store]]</code>" (but note that Finder uses <code>.DS_Store</code> even on macOS' native filesystem, [[HFS+]]).

=== <span id="UMSDOS"></span>UMSDOS permissions and filenames ===
{{further|FAT filesystem and Linux}}

Early Linux distributions also supported a format known as [[UMSDOS]], a FAT variant with Unix file attributes (such as long file name and access permissions) stored in a separate file called "<code>--linux-.---</code>". UMSDOS fell into disuse after [[#VFAT|VFAT]] was released and it is not enabled by default in [[Linux]] from version 2.5.7 onwards.<ref name="Linux_ChangeLog257" /> For some time, Linux also provided combined support for UMSDOS-style permissions and VFAT long filenames through [[UVFAT]].

=== <span id="FAT16+"></span><span id="FAT32+"></span><span id="FAT32B"></span>FAT+ ===
In 2007 the open '''FAT+''' draft proposed how to store [[Large file support|larger files]] up to 256&nbsp;GB minus 1&nbsp;byte, or 274,877,906,943 (2<sup>38</sup>&nbsp;−&nbsp;1) bytes, on slightly modified and otherwise backward-compatible FAT32 volumes,<ref name="DRDOS_FAT+_R2" /> but imposes a risk that disk tools or FAT32 implementations not aware of this extension may truncate or delete files exceeding the normal FAT32 file size limit. Support for '''FAT32+''' and '''FAT16+''' is limited to some versions of [[DR-DOS]] and not available in mainstream operating systems.<ref>{{cite web |url=http://www.drdosprojects.de/ |title=DR-DOS/OpenDOS Enhancement Project |first=Udo |last=Kuhnt |date=July 21, 2011 |access-date=2015-04-20 |archive-date=2016-07-06  |archive-url=https://web.archive.org/web/20160706205139/http://www.drdosprojects.de/ |url-status=live }}</ref> (This extension is critically incompatible with the <code>/EAS</code> option of the FAT32.IFS method to store [[FAT extended file attributes|OS/2 extended attributes]] on FAT32 volumes.)

== Derivatives ==

=== Turbo FAT ===
{{Main|Turbo FAT}}

In its [[NetWare File System]] ([[NWFS]]) [[Novell]] implemented a heavily modified variant of a FAT file system for the [[NetWare]] operating system. For larger files it utilized a performance feature named [[Turbo FAT]].

=== FATX ===
<!-- NB. The header "FATX" is used in redirects to this page. -->
<!-- {{Main|FATX}} should be created instead of further expanding this FATX section -->

FATX is a family of file systems designed for [[Microsoft]]'s [[Xbox (console)|Xbox]] [[video game console]] [[hard disk]] drives and [[memory card]]s,<ref name="Xbox_FATX-Spec" /><ref name="Xbox_Linux" /> introduced in 2001.

While resembling the same basic design ideas as [[#FAT16|FAT16]] and [[#FAT32|FAT32]], the '''FATX16''' and '''FATX32''' on-disk structures are simplified, but fundamentally incompatible with normal FAT16 and FAT32 file systems, making it impossible for normal FAT file system drivers to mount such volumes.

The non-bootable [[superblock (file systems)|superblock]] sector is 4&nbsp;KB in size and holds an 18&nbsp;byte large BPB-like structure completely different from normal [[FAT BPB|BPB]]s. Clusters are typically 16&nbsp;KB in size and there is only one copy of the FAT on the Xbox. Directory entries are 64&nbsp;bytes in size instead of the normal [[FAT directory entry|32&nbsp;bytes]]. Files can have filenames up to 42 characters long using the [[OEM character set]]<!-- not Unicode --> and be up to 4&nbsp;GB minus 1&nbsp;byte in size. The on-disk timestamps hold creation, modification and access dates and times but differ from FAT: in FAT, the [[Epoch (computing)|epoch]] is [[Epoch of 1980-01-01|1980]]; in FATX, the epoch is [[Epoch of 2000-01-01|2000]]. On the [[Xbox 360]], the epoch is 1980.<ref name="Xbox360_FATX" />

=== exFAT ===
{{Main|exFAT}}

exFAT is a file system introduced with [[Windows Embedded CE 6.0]] in November 2006 and brought to the Windows&nbsp;NT family with [[Windows Vista Service Pack 1|Vista Service Pack 1]] and [[Windows XP Service Pack 3]] (or separate installation of Windows&nbsp;XP Update KB955704). It is loosely based on the File Allocation Table architecture, but incompatible, proprietary and protected by patents.<ref name="Microsoft_exFAT-License" />

exFAT is intended for use on [[flash drive]]s and [[memory card]]s such as [[SDXC]] and [[Memory Stick XC]], where FAT32 is otherwise used. Vendors usually pre-format SDXC cards with it. Its main benefit is its exceeding of the 4&nbsp;GB file size limit, as file size references are stored with eight instead of four bytes, increasing the limit to 2<sup>64</sup>&nbsp;−&nbsp;1 bytes.

Microsoft's [[Graphical user interface|GUI]] and command-line format utilities offer it as an alternative to [[NTFS]] (and, for smaller partitions, to [[#FAT16B|FAT16B]] and [[#FAT32|FAT32]]). The [[Master Boot Record|MBR]] [[partition type]] is <code>[[Partition type#PID_07h|0x07]]</code> (the same as used for [[Installable File System|IFS]], [[High Performance File System|HPFS]], and NTFS). Logical geometry information located in the [[Volume Boot Record|VBR]] is stored in a format not resembling any kind of BPB.

In early 2010, the file system was [[reverse engineering|reverse-engineered]] by the [[SANS Institute]].<ref>{{Cite web|url=https://www.sans.org/reading-room/whitepapers/forensics/reverse-engineering-microsoft-exfat-file-system-33274|title=Reverse Engineering the Microsoft exFAT File System {{pipe}} SANS Institute|access-date=2021-03-20 |archive-date=2021-04-21 |archive-url=https://web.archive.org/web/20210421210732/https://www.sans.org/reading-room/whitepapers/forensics/reverse-engineering-microsoft-exfat-file-system-33274|url-status=live}}</ref> On August 28, 2019, Microsoft published the technical specification for exFAT so that it can be used in the Linux kernel and other operating systems.<ref>{{cite web
 | title = exFAT in the Linux kernel? Yes!
 | url = https://cloudblogs.microsoft.com/opensource/2019/08/28/exfat-linux-kernel/
 | website = Microsoft Open Source Blog
 | date = August 28, 2019
 | access-date = October 6, 2019
 | archive-date = 2019-09-01 
 | archive-url = https://web.archive.org/web/20190901180353/https://cloudblogs.microsoft.com/opensource/2019/08/28/exfat-linux-kernel/
 | url-status = live
 }}</ref>

== <span id="Legal"></span>Patents ==

Microsoft applied for, and was granted, a series of patents for key parts of the FAT file system in the mid-1990s. All four pertain to long-filename extensions to FAT first seen in [[Windows 95]]: U.S. patent 5,579,517,<ref name=patent5579517>{{cite patent |inventor1-last=Reynolds |inventor1-first=Aaron R. |inventor2-last=Adler |inventor2-first=Dennis R. |inventor3-last=Lipe |inventor3-first=Ralph A. |inventor4-last=Pedrizetti |inventor4-first=Ray D. |title=Common name space for long and short filenames |issue-date=1996 |patent-number=5579517 |country-code=US }}</ref> U.S. patent 5,745,902,<ref>{{cite patent |inventor1-last=Miller |inventor1-first=Thomas J. |inventor2-last=Kimura |inventor2-first=Gary D. |title=Method and system for accessing a file using file names having different file name formats |issue-date=1998 |patent-number=5745902 |country-code=US }}</ref> U.S. patent 5,758,352,<ref name=patent5758352>{{cite patent |inventor1-last=Reynolds |inventor1-first=Aaron R. |inventor2-last=Adler |inventor2-first=Dennis R. |inventor3-last=Lipe |inventor3-first=Ralph A. |inventor4-last=Pedrizetti |inventor4-first=Ray D. |title=Common name space for long and short filenames |issue-date=1998 |patent-number=5758352 |country-code=US }}</ref> U.S. patent 6,286,013 (all expired since 2013).<ref>{{cite patent |inventor1-last=Reynolds |inventor1-first=Aaron R. |inventor2-last=Adler |inventor2-first=Dennis R. |inventor3-last=Lipe |inventor3-first=Ralph A. |inventor4-last=Pedrizetti |inventor4-first=Ray D. |title=Method and system for providing a common name space for long and short file names in an operating system |issue-date=1996 |patent-number=6286013 |country-code=US }}</ref>

On December 3, 2003, Microsoft announced<ref name="Microsoft_2003_FAT32" /> that it would be offering licenses for use of its FAT specification and "associated intellectual property", at the cost of a {{US$|0.25}} royalty per unit sold, with a {{US$|250000}} maximum royalty per license agreement.<ref name="Microsoft_FAT_File_System" /> To this end, Microsoft cited four patents on the FAT file system as the basis of its intellectual property claims.

In the EFI FAT32 specification,<ref name="efi" /> Microsoft specifically grants a number of rights, which many readers have interpreted as permitting operating system vendors to implement FAT.<ref>{{cite web |url=https://www.youtube.com/watch?v=V2aq5M3Q76U | archive-url=https://ghostarchive.org/varchive/youtube/20211102/V2aq5M3Q76U| archive-date=2021-11-02 | url-status=live|title=EFI and Linux: the future is here, and it's awful |first=Matthew |last=Garrett |date=January 19, 2012 |work=[[linux.conf.au]] |publisher=YouTube |access-date=2014-01-12 }}{{cbignore}}</ref> Non-Microsoft patents affecting FAT include: U.S. patent 5,367,671, specific to the [[OS/2]] extended object attributes (expired in 2011).<ref>{{cite patent |inventor1-last=Feigenbaum |inventor1-first=Barry A. |inventor2-last=Miro |inventor2-first=Felix |title=System for accessing extended object attribute (EA) data through file name or EA handle linkages in path tables |issue-date=1994 |patent-number=5367671 |country-code=US }}</ref>

=== Challenges and lawsuits ===
The Public Patent Foundation (PUBPAT) submitted evidence to the [[USPTO|US Patent and Trademark Office]] (USPTO) in 2004 disputing the validity of U.S. patent 5,579,517,<ref name=patent5579517 /> including prior art references from [[Xerox]] and IBM.<ref>{{cite web |url=http://www.pubpat.org/assets/files/MicrosoftFAT/Reynolds_517_Reexam_Request.pdf |title=PUBPAT's Request for Reexamination of Microsoft's FAT Patent |last=Ravicher |first=Daniel B. |publisher=Public Patent Foundation |date=April 15, 2004 |access-date=2014-01-12 |archive-date=2013-06-07  |archive-url=https://web.archive.org/web/20130607091551/http://www.pubpat.org/assets/files/MicrosoftFAT/Reynolds_517_Reexam_Request.pdf |url-status=live }}</ref> The USPTO opened an investigation and concluded by rejecting all claims in the patent.<ref>{{cite web |url=http://www.pubpat.org/assets/files/MicrosoftFAT/Reynolds_517_Rejected_040916.PDF |title=Patent Office's Office Action Rejecting Microsoft FAT Patent |author=USPTO |publisher=Public Patent Foundation |date=September 30, 2004 |access-date=2014-01-12 |author-link=USPTO |archive-date=2013-05-26  |archive-url=https://web.archive.org/web/20130526003038/http://www.pubpat.org/assets/files/MicrosoftFAT/Reynolds_517_Rejected_040916.PDF |url-status=live }}</ref> The next year, the USPTO further announced that following the re-examination process, it affirmed the rejection of '517 and additionally found U.S. patent 5,758,352<ref name=patent5758352 /> invalid on the grounds that the patent had incorrect assignees.

However, in 2006, the USPTO ruled that features of Microsoft's implementation of the FAT system were "novel and non-obvious", reversing both earlier decisions and leaving the patents valid.<ref name="CNET_2006-01-10" />

In February 2009, Microsoft filed a [[patent infringement]] lawsuit against [[TomTom]] alleging that the device maker's products infringe on patents related to [[#VFAT|VFAT]] long filenames. As some TomTom products are based on [[Linux]], this marked the first time that Microsoft tried to enforce its patents against the Linux platform.<ref name="ARSTechnica_2009" /> The lawsuit was settled out of court the following month with an agreement that Microsoft be given access to four of TomTom's patents, that TomTom will drop support for the VFAT long filenames from its products, and that in return Microsoft not seek legal action against TomTom for the five-year duration of the settlement agreement.<ref name="CNET_2009" />

In October 2010, Microsoft filed a patent infringement lawsuit against [[Motorola]] alleging several patents (including two of the VFAT patents) were not licensed for use in the [[Android (operating system)|Android]] operating system.<ref name="Microsoft_Motorola" /> They also submitted a complaint to the [[United States International Trade Commission|ITC]].<ref name="ARSTechnica_2010" />
Developers of open source software have designed methods intended to circumvent Microsoft's patents.<ref name="ArsTechnica_2009" /><ref name="DesktopLinux_2009" />

In 2013, patent EP0618540 "common name space for long and short filenames" (expired since 2014<ref>{{Cite patent|title=Common name space for long and short filenames|gdate=1994-03-31|url=https://patents.google.com/patent/EP0618540B1/en}} {{Cite web |url=https://patents.google.com/patent/EP0618540B1/en |title=EP0618540B1 - Common name space for long and short filenames - Google Patents |access-date=2021-05-07  |archive-date=2020-03-28  |archive-url=https://web.archive.org/web/20200328120538/https://patents.google.com/patent/EP0618540B1/en |url-status=bot: unknown }}</ref>) was invalidated in Germany.<ref>{{cite web |url=http://www.fosspatents.com/2013/12/federal-patent-court-of-germany.html |title=Federal Patent Court of Germany invalidates Microsoft FAT patent, appeals court may disagree |first=Florian |last=Müller |publisher=FOSS Patents |date=December 5, 2013 |access-date=2014-01-12 |archive-date=2014-01-04  |archive-url=https://web.archive.org/web/20140104122540/http://www.fosspatents.com/2013/12/federal-patent-court-of-germany.html |url-status=live }}</ref> After the appeal was withdrawn, this judgment became final on 28 October 2015.<ref>{{cite web |url=https://www.ifross.org/artikel/bundespatentgericht-erkl-rt-vfat-patent-erneut-f-r-nichtig |title=Bundespatentgericht erklärt VFAT-Patent erneut für nichtig |first=Stefan |last=Labesius |publisher=ifrOSS |date=May 28, 2017 |access-date=2019-08-02 |archive-date=2019-08-02  |archive-url=https://web.archive.org/web/20190802132657/https://www.ifross.org/artikel/bundespatentgericht-erkl-rt-vfat-patent-erneut-f-r-nichtig |url-status=live }}</ref>

== See also ==

* [[Comparison of file systems]]
* [[Design of the FAT file system]]
* [[Drive letter assignment]]
* [[List of file systems]]
* [[Transaction-Safe FAT File System]]

== Notes ==
<references group="nb">
<ref group="nb" name="NB_NCR_FAT">Sources differ in regard to the first NCR data entry terminal integrating support for the FAT file system. According to [[Stephen Manes]] and Paul Andrews, "Gates",<!--<ref name="Manes_1993_Gates" /> --> development was for a [[NCR 8200]] in late 1977, incorrectly classified as a floppy-based upgrade to the [[NCR 7200]], which had been released in 1975-11 ([[NCR 7200 model I|model I]] and [[NCR 7200 model IV|IV]]) and was built around an [[Intel 8080]] 8-bit processor, but was cassette-based only. However, the NCR Century 8200 was a 16-bit minicomputer, onto which several data entry terminals could be hooked up. [[Marc McDonald]] even remembered<!-- in 2012-08 --> a [[NCR 8500]], a mainframe of the Criterion series, which can be ruled out as well. Announced 1977-10 for shipment in 1978-02, NCR also introduced the [[NCR I-8100]] series including the 8080-based [[NCR I-8130]] and [[NCR I-8150]] models of small business systems featuring dual floppy disks. Other sources indicate that either the NCR 7200 series itself or the successor series were the actual target platform. [[NCR Basic Plus 6]] (based on [[Microsoft Extended BASIC-80]]) became available for the cassette-based [[NCR 7200 model VI]] in Q1/1977.<!-- https://books.google.com/books?id=XEToBl0e2NIC&printsec=frontcover --> The [[NCR 7500]] series was released in 1978, based on a similar 8080 hardware, but now including [[NCR 7520]] and [[NCR 7530|7530]] models featuring 8-inch diskettes. [[NCR Basic +6]], a precursor or adaptation of [[Standalone Disk BASIC-80]] was available for them at least since 1979. One source<!-- http://www.thecorememory.com/forum/index.php?topic=83.msg342#msg342 --> claims that a special NCR 7200 model variant with two 8-inch diskettes and Microsoft BASIC existed and was imported by NCR Sydney into Australia the least.</ref>
<ref group="nb" name="NB_VFAT_Name">A driver named [[#VFAT|VFAT]] appeared before [[Windows 95]], in [[Windows for Workgroups]] 3.11, but this older version was only used for implementing [[32-bit file access]] and did not support [[long file name]]s.</ref>
</references><references group="nb" /><!-- {{Reflist|group="nb"}} -->

== References ==
<references>
<ref name="Microsoft_1979_BASIC80-50">{{cite book |title=Xerox BASIC-80 – basic-80 reference manual |year=1979 |version=5.0 |publisher=[[Microsoft]], [[Xerox]] |id=610P70641 |url=http://bitsavers.trailing-edge.com/pdf/xerox/820-II/BASIC-80_5.0.pdf |access-date=2014-06-02<!--, 8101-530-07--> |archive-date=2016-03-04  |archive-url=https://web.archive.org/web/20160304120148/http://bitsavers.trailing-edge.com/pdf/xerox/820-II/BASIC-80_5.0.pdf |url-status=live }} (NB. For Microsoft (Standalone Disk / Disk / Extended / 8K) BASIC-80, (Standalone Disk / Extended) BASIC-86, BASIC Compiler, release 5.0)</ref>
<ref name="Microsoft_1979_BASIC80-51">{{cite book |title=MICROSOFT BASIC-80 version 5.0 reference manual / BASIC-80 Interpreter and Compiler Addendum Release 5.1 |year=1979 |version=5.1 |publisher=[[Microsoft]] |url=http://bitsavers.trailing-edge.com/pdf/xerox/820-II/BASIC-80_5.0.pdf |access-date=2014-06-02<!--, 8101-530-07--> |archive-date=2016-03-04  |archive-url=https://web.archive.org/web/20160304120148/http://bitsavers.trailing-edge.com/pdf/xerox/820-II/BASIC-80_5.0.pdf |url-status=live }} (NB. For Microsoft (Standalone Disk / Disk / Extended / 8K) BASIC-80, (Standalone Disk / Extended) BASIC-86, BASIC Compiler, release 5.1)</ref>
<ref name="BYTE_1980_86-DOS">{{cite magazine |title=86-DOS - 8086 OPERATING SYSTEM - $95 |author=Seattle Computer Products |author-link=Seattle Computer Products |magazine=[[Byte (magazine)|Byte]] |volume=5 |number=8 |date=August 1980 |publisher=[[BYTE Publications Inc.]] |issn=0360-5280 |id={{CODEN|BYTEDJ}} |type=Advertisement |page=173 |url=https://archive.org/stream/byte-magazine-1980-08/1980_08_BYTE_05-08_The_Forth_Language#page/n173/mode/2up |access-date=2013-08-18 }} [https://tech-insider.org/personal-computers/research/acrobat/8008-a.pdf] {{Webarchive|url=https://web.archive.org/web/20200201163325/https://tech-insider.org/personal-computers/research/acrobat/8008-a.pdf |date=2020-02-01  }} (NB. The SCP advertisement already calls the product ''86-DOS'', but does not mention a specific version number. Version 0.3 is known to be called 86-DOS already, so the name change must have taken place either for version 0.2 or immediately afterwards in August 1980.)</ref>
<ref name="Hunter_1983_Softalk">{{cite journal |first=David |last=Hunter |date=1983 |title=Tim Paterson – The roots of DOS |journal=Softalk for the IBM Personal Computer |issue=March 1983 |url=http://www.patersontech.com/dos/softalk.aspx |access-date=2014-06-02 |archive-url=https://web.archive.org/web/20190906120449/http://www.patersontech.com/dos/softalk.aspx |archive-date=September 6, 2019 |url-status=dead }}</ref>
<ref name="Manes_1993_Gates">{{cite book | first1=Stephen |last1=Manes |first2=Paul |last2=Andrews | year=1993 | title=Gates: How Microsoft's Mogul Reinvented an Industry—and Made Himself the Richest Man in America | publisher=Doubleday | isbn=0-385-42075-7}}</ref>
<ref name="IBM_1984_PCDOS30">IBM (1984). ''IBM PC DOS 3.0 announcement letter''.</ref>
<ref name="IBM_1985_Reference">IBM (1985). ''IBM PC DOS Technical Reference''. First Edition, P/N 6024181, dated February 1985.</ref>
<ref name="Ecma-107">{{cite web |url=http://www.ecma-international.org/publications/standards/Ecma-107.htm |title=Volume and File Structure of Disk Cartridges for Information Interchange |work=Standard ECMA-107 (2nd ed., June 1995) |publisher=[[Ecma International|ECMA]] |year=1995 |access-date=2011-07-30 |archive-date=2018-10-07  |archive-url=https://web.archive.org/web/20181007174227/http://ecma-international.org/publications/standards/Ecma-107.htm |url-status=live }}</ref>
<ref name="ISO_9293_1994">{{cite web |url=http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=21273 |title=Information technology – Volume and file structure of disk cartridges for information interchange |work=ISO/IEC 9293:1994 |publisher=[[International Organization for Standardization|ISO]] catalogue |year=1994 |access-date=2012-01-06 |archive-date=2012-01-17  |archive-url=https://web.archive.org/web/20120117180640/http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=21273 |url-status=live }}</ref>
<ref name="ISO_9293_1987">{{cite web |url=http://www.iso.org/iso/iso_catalogue/catalogue_ics/catalogue_detail_ics.htm?csnumber=16948 |title=Information processing – Volume and file structure of flexible disk cartridges for information interchange |work=ISO 9293:1987 |publisher=[[International Organization for Standardization|ISO]] catalogue |year=1987 |access-date=2012-01-06 |archive-date=2012-01-17  |archive-url=https://web.archive.org/web/20120117181849/http://www.iso.org/iso/iso_catalogue/catalogue_ics/catalogue_detail_ics.htm?csnumber=16948 |url-status=live }}</ref>
<ref name="Patent_5758352">{{cite web |url=https://patents.google.com/patent/US5758352A/en |date=May 26, 1998 |title=Common name space for long and short filenames |author-link1=Aaron R. Reynolds |first1=Aaron R. |last1=Reynolds |first2=Dennis R. |last2=Adler |first3=Ralph A. |last3=Lipe |first4=Ray D. |last4=Pedrizetti |first5=Jeffrey T. |last5=Parsons |first6=Rasipuram V. |last6=Arun |work=US Patent 5758352 |access-date=2025-06-25}}</ref>
<ref name="Duncan_1988_MS-DOS_Encyclopedia">{{cite book |title=The MS-DOS Encyclopedia: versions 1.0 through 3.2 |author-first1=Ray |author-last1=Duncan |author-first2=Steve |author-last2=Bostwick |author-first3=Keith |author-last3=Burgoyne<!--   |author-first4=Robert A. |author-last4=Byers |author-first5=Thom |author-last5=Hogan |author-first6=Jim |author-last6=Kyle |author-first7=Gordon |author-last7=Letwin |author-link7=Gordon Letwin |author-first8=Charles |author-last8=Petzold |author-link8=Charles Petzold |author-first9=Chip |author-last9=Rabinowitz |author-first10=Jim |author-last10=Tomlin |author-first11=Richard |author-last11=Wilton |author-first12=Van |author-last12=Wolverton |author-first13=William |author-last13=Wong |author-first14=JoAnne |author-last14=Woodcock |contribution=Technical advisors |contributor-first1=Mark |contributor-last1=Zbikowski |contributor-link1=Mark Zbikowski |contributor-first2=Paul |contributor-last2=Allen |contributor-link2=Paul Allen |contributor-first3=Steve |contributor-last3=Ballmer |contributor-link3=Steve Ballmer |contributor-first4=Reuben |contributor-last4=Borman |contributor-first5=Rob |contributor-last5=Borman |contributor-first6=John |contributor-last6=Butler |contributor-first7=Chuck |contributor-last7=Carroll |contributor-first8=Mark |contributor-last8=Chamberlain |contributor-first9=David |contributor-last9=Chell |contributor-first10=Mike |contributor-last10=Colee |contributor-first11=Mike |contributor-last11=Courtney |contributor-first12=Mike |contributor-last12=Dryfoos |contributor-first13=Rachel |contributor-last13=Duncan |contributor-first14=Kurt |contributor-last14=Eckhardt |contributor-first15=Eric |contributor-last15=Evans |contributor-first16=Rick |contributor-last16=Farmer |contributor-first17=Bill |contributor-last17=Gates |contributor-link17=Bill Gates |contributor-first18=Michael |contributor-last18=Geary |contributor-first19=Bob |contributor-last19=Griffin |contributor-first20=Doug |contributor-last20=Hogarth |contributor-first21=James W. |contributor-last21=Johnson |contributor-first22=Kaamel |contributor-last22=Kermaani |contributor-first23=Adrian |contributor-last23=King |contributor-first24=Reed |contributor-last24=Koch |contributor-first25=James |contributor-last25=Landowski |contributor-first26=Chris |contributor-last26=Larson |contributor-first27=Thomas |contributor-last27=Lennon |contributor-first28=Dan |contributor-last28=Lipkie |contributor-first29=Marc |contributor-last29=McDonald |contributor-link29=Marc McDonald |contributor-first30=Bruce |contributor-last30=McKinney |contributor-first31=Pascal |contributor-last31=Martin |contributor-first32=Estelle |contributor-last32=Mathers |contributor-first33=Bob |contributor-last33=Matthews |contributor-first34=David |contributor-last34=Melin |contributor-first35=Charles |contributor-last35=Mergentime |contributor-first36=Randy |contributor-last36=Nevin |contributor-first37=Dan |contributor-last37=Newell |contributor-first38=Tani |contributor-last38=Newell |contributor-first39=David |contributor-last39=Norris |contributor-first40=Mike |contributor-last40=O'Leary |contributor-first41=Bob |contributor-last41=O'Rear |contributor-link41=Bob O'Rear |contributor-first42=Mike |contributor-last42=Olsson |contributor-first43=Larry |contributor-last43=Osterman |contributor-first44=Ridge |contributor-last44=Ostling |contributor-first45=Sunil |contributor-last45=Pai |contributor-first46=Tim |contributor-last46=Paterson |contributor-link46=Tim Paterson |contributor-first47=Gary |contributor-last47=Perez |contributor-first48=Chris |contributor-last48=Peters |contributor-first49=Charles |contributor-last49=Petzold |contributor-link49=Charles Petzold |contributor-first50=John |contributor-last50=Pollock |contributor-first51=Aaron |contributor-last51=Reynolds |contributor-link51=Aaron R. Reynolds |contributor-first52=Darryl |contributor-last52=Rubin |contributor-first53=Ralph |contributor-last53=Ryan |contributor-first54=Karl |contributor-last54=Schulmeisters |contributor-first55=Rajen |contributor-last55=Shah |contributor-first56=Barry |contributor-last56=Shaw |contributor-first57=Anthony |contributor-last57=Short |contributor-first58=Ben |contributor-last58=Slivka |contributor-first59=Jon |contributor-last59=Smirl |contributor-first60=Betty |contributor-last60=Stillmaker |contributor-first61=John |contributor-last61=Stoddard |contributor-first62=Dennis |contributor-last62=Tillman |contributor-first63=Greg |contributor-last63=Whitten |contributor-first64=Natalie |contributor-last64=Yount |contributor-first65=Steve |contributor-last65=Zeck -->|date=1988 |edition=Completely reworked |publisher=[[Microsoft Press]] |location=Redmond, Washington, USA |isbn=1-55615-049-0 |lccn=87-21452 |oclc=16581341}} (xix+1570 pages; 26&nbsp;cm) (NB. This edition was published in 1988 after extensive rework of the withdrawn 1986 first edition by a different team of authors. [https://www.pcjs.org/pubs/pc/reference/microsoft/mspl13/msdos/encyclopedia/] {{Webarchive|url=https://web.archive.org/web/20181014053041/https://www.pcjs.org/pubs/pc/reference/microsoft/mspl13/msdos/encyclopedia/ |date=2018-10-14  }})</ref>
<ref name="Schulman_1994_Undocumented-DOS">{{cite book |author-first1=Andrew |author-last1=Schulman |author-first2=Ralf D. |author-last2=Brown |author-link2=Ralf D. Brown |author-first3=David |author-last3=Maxey |author-first4=Raymond J. |author-last4=Michels |author-first5=Jim |author-last5=Kyle |title=Undocumented DOS: A programmer's guide to reserved MS-DOS functions and data structures - expanded to include MS-DOS 6, Novell DOS and Windows 3.1 |publisher=[[Addison Wesley]] |edition=2 |date=1994 |orig-year=November 1993<!-- first printing --> |isbn=0-201-63287-X |location=Reading, Massachusetts |page=[https://archive.org/details/undocumenteddosp00andr_0/page/11 11] |url=https://archive.org/details/undocumenteddosp00andr_0/page/11}} (xviii+856+vi pages, 3.5"-floppy) Errata: [https://web.archive.org/web/20190417215556/http://www.cs.cmu.edu/afs/cs/user/ralf/pub/books/UndocumentedDOS/errata.ud2][https://web.archive.org/web/20190417212906/https://www.pcjs.org/pubs/pc/programming/Undocumented_DOS/#errata-2nd-edition]</ref>
<ref name="Wallace_1992_Harddrive">Wallace, James; Erickson, Jim; (1992); ''Hard Drive: Bill Gates and the Making of the Microsoft Empire'', John Wiley & Sons, {{ISBN|0-471-56886-4}}</ref>
<ref name="Paterson_2007_Design-DOS">{{cite web |url=http://dosmandrivel.blogspot.com/2007/09/design-of-dos.html |date=September 30, 2007 |author-link=Tim Paterson |first=Tim |last=Paterson |title=Design of DOS |work=DosMan Drivel |access-date=2011-07-04 |archive-date=2013-01-20  |archive-url=https://web.archive.org/web/20130120075653/http://dosmandrivel.blogspot.com/2007/09/design-of-dos.html |url-status=live }}</ref>
<ref name="Norton2">[[Peter Norton|Norton, Peter]]; (1986); ''Inside the IBM PC, Revised and Enlarged'', Brady, {{ISBN|0-89303-583-1}}, p. 157</ref>
<ref name="Jenkinson_2000_Forensic">{{cite book |first1=Brian |last1=Jenkinson |last2=Sammes |first2=A. J. |title=Forensic Computing: A Practitioner's Guide (Practitioner Series) |url=https://archive.org/details/forensiccomputin00samm_915 |url-access=limited |publisher=Springer |location=Berlin |year=2000 |page=[https://archive.org/details/forensiccomputin00samm_915/page/n163 157] |isbn=1-85233-299-9 |quote=... only 2^12 (that is, 4096) allocation units or clusters can be addressed. In fact, the number is less than this, since 000h and 001h are not used and FF0h to FFFh are reserved or used for other purposes, leaving 002h to FEFh (2 to 4079) as the range of possible clusters.}}</ref>
<ref name="efi">{{cite web |url=http://download.microsoft.com/download/1/6/1/161ba512-40e2-4cc9-843a-923143f3456c/fatgen103.doc |title=Microsoft Extensible Firmware Initiative FAT32 File System Specification, FAT: General Overview of On-Disk Format |publisher=[[Microsoft]] |date=March 30, 2011 |access-date=2018-12-21 |archive-date=2021-07-23  |archive-url=https://web.archive.org/web/20210723100623/http://download.microsoft.com/download/1/6/1/161ba512-40e2-4cc9-843a-923143f3456c/fatgen103.doc |url-status=live }}</ref>
<ref name="Brouwer_2002_Partition-IDs">{{cite web |url=http://www.win.tue.nl/~aeb/partitions/partition_types-1.html |title=List of partition identifiers for PCs |first=Andries |last=Brouwer |access-date=2012-01-11  |archive-date=2019-04-23  |archive-url=https://web.archive.org/web/20190423204723/http://www.win.tue.nl/~aeb/partitions/partition_types-1.html |url-status=live }}</ref>
<ref name="Brouwer_2002_Logical_FAT">{{cite web |url=https://www.win.tue.nl/~aeb/partitions/partition_types-2.html#ss2.6 |title=Properties of partition tables |first=Andries |last=Brouwer |access-date=2012-01-11  |archive-date=2019-04-23  |archive-url=https://web.archive.org/web/20190423204726/https://www.win.tue.nl/~aeb/partitions/partition_types-2.html#ss2.6 |url-status=live }}</ref>
<ref name="Microsoft_2003_CC736327">{{cite web |url=https://technet.microsoft.com/en-us/library/cc736327(v=ws.10).aspx |title=Dskprobe Overview: Data Recovery |publisher=[[Microsoft TechNet]] |date=March 28, 2003 |access-date=2011-08-03 |archive-date=2011-07-03  |archive-url=https://web.archive.org/web/20110703230849/http://technet.microsoft.com/en-us/library/cc736327(v=WS.10).aspx |url-status=live }}</ref>
<ref name="Microsoft_2004_KB120138">{{cite web |url=http://c-bit.org/kb/120138/EN-US/ |title=Errors Creating Files or Folders in the Root Directory |publisher=Microsoft Help and Support |date=December 16, 2004 |access-date=2006-10-14 |archive-date=2020-07-31  |archive-url=https://web.archive.org/web/20200731141634/http://c-bit.org/kb/120138/EN-US/ |url-status=live }}</ref>
<ref name="Microsoft_1998_CC768180">{{cite web |url=https://technet.microsoft.com/en-us/library/cc768180.aspx |title=Windows 98 Resource Kit – Chapter 10 – Disks and File Systems |publisher=[[Microsoft TechNet]] |year=1998 |access-date=2012-07-16 |archive-date=2012-05-01  |archive-url=https://web.archive.org/web/20120501150154/http://technet.microsoft.com/en-us/library/cc768180.aspx |url-status=live }}</ref>
<ref name="MKDOSFS">{{cite web |url=http://www.die.net/doc/linux/man/man8/mkdosfs.8.html |title=mkdosfs man page |access-date=2006-11-21  |archive-date=2006-10-07  |archive-url=https://web.archive.org/web/20061007182356/http://www.die.net/doc/linux/man/man8/mkdosfs.8.html |url-status=live }}</ref>
<ref name="Microsoft_2007_KB184006">{{cite web |url=http://c-bit.org/kb/184006/EN-US/ |title=Limitations of FAT32 File System |quote=Clusters cannot be 64&nbsp;kilobytes (<abbr title=""kilobyte"; should be "kilobyte" (1024 or 2×512&nbsp;bytes)">KB</abbr>) or larger |date=March 26, 2007 |publisher=[[Microsoft Knowledge Base]] |access-date=2011-08-21 |archive-date=2020-07-31  |archive-url=https://web.archive.org/web/20200731085746/http://c-bit.org/kb/184006/EN-US/ |url-status=live }}</ref>
<ref name="Microsoft_2007_KB314463">{{cite web |url=http://c-bit.org/kb/314463/EN-US/ |title=Limitations of the FAT32 File System in Windows XP |date=December 1, 2007 |publisher=[[Microsoft Knowledge Base]] |access-date=2011-08-21 |archive-date=2020-07-31  |archive-url=https://web.archive.org/web/20200731081921/http://c-bit.org/kb/314463/EN-US/ |url-status=live }}</ref>
<ref name="Eager_2000_Tavi">{{cite web |url=http://www.tavi.co.uk/os2pages/eadata.html |title=Implementation of extended attributes on the FAT file system |first=Bob |last=Eager |work=Tavi OS/2 pages |date=October 28, 2000 |access-date=2006-10-14 |archive-url=https://web.archive.org/web/20060613212300/http://www.tavi.co.uk/os2pages/eadata.html |archive-date=June 13, 2006 |url-status=dead }}</ref>
<ref name="Linux_ChangeLog257">{{cite web |url=https://www.kernel.org/pub/linux/kernel/v2.5/ChangeLog-2.5.7 |title=Release notes for v2.5.7 |publisher=The Linux Kernel archives |date=March 12, 2002 |access-date=2006-10-14 |archive-date=2006-04-15  |archive-url=https://web.archive.org/web/20060415030215/http://www.kernel.org/pub/linux/kernel/v2.5/ChangeLog-2.5.7 |url-status=live }}</ref>
<ref name="Xbox_FATX-Spec">{{cite web |url=http://www.free60.org/wiki/FATX |title=FATX Specification |publisher=free60 wiki |access-date=2011-08-16 |archive-date=2018-07-26  |archive-url=https://web.archive.org/web/20180726171806/http://free60.org/wiki/FATX |url-status=live }}</ref>
<ref name="Xbox_Linux">{{cite web |first1=Andrew |last1=de Quincey |first2=Lucien |last2=Murray-Pitts |version=0.13 |url=http://www.xbox-linux.org/wiki/Xbox_Partitioning_and_Filesystem_Details |title=Xbox partitioning and file system details |publisher=Xbox-Linux project |date=August 29, 2008 |access-date=2014-05-25 |archive-url=https://web.archive.org/web/20100617020539/http://www.xbox-linux.org/wiki/Xbox_Partitioning_and_Filesystem_Details |archive-date=June 17, 2010 |url-status=dead}}</ref>
<ref name="Xbox360_FATX">{{cite web |first=Michael |last=Steil |url=http://www.xbox-linux.org/wiki/Differences_between_Xbox_FATX_and_MS-DOS_FAT |title=Differences between Xbox FATX and MS-DOS FAT |publisher=Xbox-Linux project |date=February 26, 2008 |orig-year=2003<!-- 2003-11-30 --> |access-date=2014-05-25 |archive-url=https://web.archive.org/web/20100617022009/http://www.xbox-linux.org/wiki/Differences_between_Xbox_FATX_and_MS-DOS_FAT |archive-date=June 17, 2010 |url-status=dead}}</ref>
<ref name="Kelder_FAT32IFS074">Kelder, Henk; ''FAT32.TXT for FAT32.IFS version 0.74'' ({{cite web |url=http://macarlo.com/fat32v074.htm |title=@Macarlo, Inc |access-date=2012-01-14 |url-status=dead |archive-url=https://web.archive.org/web/20120330171510/http://macarlo.com/fat32v074.htm |archive-date=March 30, 2012 |df=mdy-all}}). Comment: This older version of the README file still discusses the old <code>0xEA</code> and <code>0xEC</code> magic values.</ref>
<ref name="Kelder_2003_FAT32IFS0913">Kelder, Henk; (2003); ''FAT32.TXT for FAT32.IFS version 0.9.13''. ([http://svn.netlabs.org/repos/fat32/branches/fat32-0.9/src/fat32.txt] {{Webarchive|url=https://web.archive.org/web/20130511141205/http://svn.netlabs.org/repos/fat32/branches/fat32-0.9/src/fat32.txt |date=2013-05-11  }}): "This byte [...] is not modified while running [[Windows 95]] and neighter ''[sic]'' by [[SCANDISK]] or [[DEFRAG]]. [...] If another program sets the value to <code>0x00</code> for a file that has [[extended attributes|EAs]] these EAs will no longer be found using DosFindFirst/Next calls only. The other [[OS/2]] calls for retrieving EAs (DosQueryPathInfo, DosQueryFileInfo and DosEnumAttribute) do not rely on this byte. Also the opposite could [...] occur. [...] In this situation only the performance of directory scans will be decreased. Both situations [...] are corrected by [[CHKDSK]]".</ref>
<ref name="DRDOS_FAT+_R2">{{cite web |title=FAT+ draft revision 2 |author-first1=Udo |author-last1=Kuhnt |author-first2=Luchezar I. |author-last2=Georgiev |author-first3=Jeremy |author-last3=Davis |date=2007 |format=FATPLUS.TXT |edition=2 |url=http://www.fdos.org/kernel/fatplus.txt |access-date=2015-08-05 |archive-url=https://web.archive.org/web/20150219123449/http://www.fdos.org/kernel/fatplus.txt |archive-date=February 19, 2015 |url-status=dead }}</ref>
<ref name="Microsoft_2006_ACCDATE">Microsoft (2006-11-15). [http://c-bit.org/kb/135481/EN-US/ Windows 95 CD-ROM CONFIG.TXT File] {{Webarchive|url=https://web.archive.org/web/20200731095231/http://c-bit.org/kb/135481/EN-US/ |date=2020-07-31  }} Article 135481, Revision: 1.1, retrieved 2011-12-22: "For each hard disk, specifies whether to record the date that files are last accessed. Last access dates are turned off for all drives when your computer is started in safe mode, and are not maintained for floppy disks by default. Syntax: <code>[[ACCDATE (CONFIG.SYS directive)|ACCDATE]]=drive1+|- [drive2+|-]...</code>"</ref>
<ref name="Eager_2000_EA">Eager, Bob; Tavi Systems (October 28, 2000); ''Implementation of extended attributes on the FAT file system'' ([http://www.tavi.co.uk/os2pages/eadata.html] {{Webarchive|url=https://web.archive.org/web/20060613212300/http://www.tavi.co.uk/os2pages/eadata.html |date=June 13, 2006 }})</ref>
<ref name="two">{{cite web|quote=The numbering starts with 2; the first two numbers, 0 and 1, are reserved. |url=http://www.patersontech.com/dos/Byte/InsideDos.htm#InsideDos_44 |title=An Inside Look at MS-DOS |year=1983 |publisher=[[Byte (magazine)|Byte]] |first=Tim |last=Paterson |access-date=2011-07-18 |url-status=dead |archive-url=https://web.archive.org/web/20110720115141/http://patersontech.com/Dos/Byte/InsideDos.htm |archive-date=July 20, 2011 |df=mdy}}</ref>
<ref name="Microsoft_2003_FAT32">[http://www.microsoft.com/presspass/press/2003/dec03/12-03ExpandIPPR.mspx Microsoft.com] {{webarchive|url=https://web.archive.org/web/20090822044026/http://www.microsoft.com/presspass/press/2003/dec03/12-03ExpandIPPR.mspx |date=August 22, 2009}}</ref>
<ref name="Microsoft_FAT_File_System">{{cite web |url=http://www.microsoft.com/iplicensing/productDetail.aspx?product%20title=FAT%20File%20System |archive-url=http://webarchive.loc.gov/all/20160921194326/http://www.microsoft.com/iplicensing/productDetail.aspx?product%20title=FAT%20File%20System |url-status=dead |archive-date=2016-09-21 |publisher=Microsoft |title= FAT File System |work=Intellectual Property Licensing}}</ref>
<ref name="Novell_1993_FYI.M.1101">{{citation |title=FYI – Installing DR DOS on NEC DOS 3.3 Partitions |publisher=Novell |date=January 5, 1993 |id=FYI.M.1101 |url=http://cd.textfiles.com/netwaresl/NOV_INFO/RNW93/10JAN93.MON |access-date=2014-08-12 |archive-date=2016-03-04  |archive-url=https://web.archive.org/web/20160304022753/http://cd.textfiles.com/netwaresl/NOV_INFO/RNW93/10JAN93.MON |url-status=live }}</ref>
<ref name="CNET_2006-01-10">{{cite web |url=http://www.cnet.com/news/microsofts-file-system-patent-upheld/ |title=Microsoft's file system patent upheld |date=January 10, 2006 |first=Anne |last=Broache |publisher=CNET News |access-date=2016-04-07  |archive-date=2016-05-03  |archive-url=https://web.archive.org/web/20160503195535/http://www.cnet.com/news/microsofts-file-system-patent-upheld/ |url-status=live }}</ref>
<ref name="ARSTechnica_2009">{{cite web |url=https://arstechnica.com/microsoft/news/2009/02/microsoft-sues-tomtom-over-fat-patents-in-linux-based-device.ars |title=Microsoft suit over FAT patents could open OSS Pandora's Box |last=Paul |first=Ryan |date=February 25, 2009 |access-date=2009-02-28 |publisher=arstechnica.com |archive-date=2009-02-27  |archive-url=https://web.archive.org/web/20090227181913/http://arstechnica.com/microsoft/news/2009/02/microsoft-sues-tomtom-over-fat-patents-in-linux-based-device.ars |url-status=live }}</ref>
<ref name="CNET_2009">{{cite web |url=http://news.cnet.com/8301-13860_3-10206988-56.html |title=Microsoft, TomTom settle patent dispute |last=Fried |first=Ina |date=March 30, 2009 |access-date=2009-08-22 |publisher=cnet.com |archive-date=2009-08-05  |archive-url=https://web.archive.org/web/20090805092526/http://news.cnet.com/8301-13860_3-10206988-56.html |url-status=live }}</ref>
<ref name="Microsoft_Motorola">{{cite web |url=https://www.scribd.com/doc/38550703/Micrsoft-Motorola-Patent-Suit |title=Microsoft Motorola Patent Suit |date=October 1, 2010 |access-date=2010-10-02 |archive-date=2010-10-06  |archive-url=https://web.archive.org/web/20101006014136/http://www.scribd.com/doc/38550703/Micrsoft-Motorola-Patent-Suit |url-status=live }}</ref>
<ref name="ARSTechnica_2010">{{cite web |url=https://arstechnica.com/microsoft/news/2010/10/microsoft-sues-motorola-citing-android-patent-infringement.ars |title=Microsoft sues Motorola, citing Android patent infringement |last=Protalinski |first=Emil |date=October 1, 2010 |access-date=2010-10-02 |publisher=arstechnica.com |archive-date=2010-10-02  |archive-url=https://web.archive.org/web/20101002013040/http://arstechnica.com/microsoft/news/2010/10/microsoft-sues-motorola-citing-android-patent-infringement.ars |url-status=live }}</ref>
<ref name="DesktopLinux_2009">{{cite web |url=http://www.desktoplinux.com/news/NS4980952387.html?kc=rss |title=Can FAT patch avoid Microsoft lawsuits? |last=Brown |first=Eric |date=July 2, 2009 |archive-url=https://web.archive.org/web/20130131034455/http://www.desktoplinux.com/news/NS4980952387.html |archive-date=January 31, 2013 |url-status=dead |access-date=2009-08-23 |publisher=DesktopLinux.Com}}</ref>
<ref name="ArsTechnica_2009">{{cite web |url=https://arstechnica.com/information-technology/2009/07/vfat-linux-patch-could-circumvent-microsofts-patent-claims/ |title=New Linux patch could circumvent Microsoft's FAT patents |last=Paul |first=Ryan |date=July 2, 2009 |access-date=2013-10-30 |publisher=ArsTechnica.com |archive-date=2013-11-01  |archive-url=https://web.archive.org/web/20131101061453/http://arstechnica.com/information-technology/2009/07/vfat-linux-patch-could-circumvent-microsofts-patent-claims/ |url-status=live }}</ref>
<ref name="Microsoft_2000_Wyse-DOS">{{Cite FTP |date=December 17, 2000|server=Microsoft|url-status=dead|title=Q78407: Wyse DOS 3.3 Partitions Incompatible with MS-DOS 5.x and 6.x|url=ftp://ftp.microsoft.com/misc1/PEROPSYS/MSDOS/KB/Q78/4/07.TXT}} [https://archive.org/download/ftp.microsoft.com/ftp.microsoft.com.zip/ftp.microsoft.com%2FMISC1%2FPEROPSYS%2FMSDOS%2FKB%2FQ78%2F4%2F07.TXT Alt URL]</ref>
<ref name="GB4">{{cite web |url=https://technet.microsoft.com/en-us/library/cc938937.aspx |title=File Systems |year=2001 |publisher=[[Microsoft TechNet]] |access-date=2011-07-31 |archive-date=2011-08-12  |archive-url=https://web.archive.org/web/20110812044910/http://technet.microsoft.com/en-us/library/cc938937.aspx |url-status=live }}</ref>
<ref name="IBM_4690_User_Guide">IBM; ''4690 OS User's Guide Version 5.2'', IBM document SC30-4134-01, 2008-01-10 ([https://public.dhe.ibm.com/software/retail/pubs/sw/opsys/4690/ver5r2/bsf1_UG_mst.pdf] )</ref>
<ref name="IBM_4690_Programming_Guide">IBM; ''4690 OS Programming Guide Version 5.2'', IBM document SC30-4137-01, 2007-12-06 ([https://public.dhe.ibm.com/software/retail/pubs/sw/opsys/4690/ver5r2/bsi1_PG_mst.pdf] )</ref>
<ref name="Microsoft_2000_Logical-sectoring">{{Cite FTP |date=December 17, 2000|server=Microsoft|url-status=dead|title=Q68176: Upgrading Pre-4.0 Systems with Logical Drive(s) > 32 MB|url=ftp://ftp.microsoft.com/misc1/PEROPSYS/MSDOS/KB/Q68/1/76.TXT}} [https://archive.org/download/ftp.microsoft.com/ftp.microsoft.com.zip/ftp.microsoft.com%2FMISC1%2FPEROPSYS%2FMSDOS%2FKB%2FQ68%2F1%2F76.TXT Alt URL]</ref>
<ref name="SCP_1981_86-DOS_1.0_Addendum">{{cite web |url=http://bitsavers.informatik.uni-stuttgart.de/pdf/seattleComputer/86-DOS_1.0_Addendum.pdf |title=SCP 86-DOS 1.0 Addendum |author=Seattle Computer Products |year=1981 |access-date=2013-03-10 |archive-date=2012-10-03  |archive-url=https://web.archive.org/web/20121003100657/http://bitsavers.informatik.uni-stuttgart.de/pdf/seattleComputer/86-DOS_1.0_Addendum.pdf |url-status=live }}</ref>
<ref name="Microsoft_exFAT-License">{{cite web |url=http://www.microsoft.com/en-us/legal/intellectualproperty/IPLicensing/Programs/exFATFileSystem.aspx |title=exFAT File System Intellectual Property licensing program |author=Microsoft |website=[[Microsoft]] |access-date=2013-04-23 |url-status=dead |archive-url=https://web.archive.org/web/20130507183540/http://www.microsoft.com/en-us/legal/intellectualproperty/IPLicensing/Programs/exFATFileSystem.aspx |archive-date=May 7, 2013 |df=mdy}}</ref>
<ref name="DC-009-2010">{{cite web|url=http://www.cipa.jp/english/hyoujunka/kikaku/pdf/DC-009-2010_E.pdf |title=Standard of the Camera & Imaging Products Association, CIPA DC-009-Translation-2010, Design rule for Camera File system: DCF Version 2.0 (Edition 2010) |author=JEIDA/JEITA/CIPA |year=2010 |access-date=2011-04-13 |url-status=dead |archive-url=https://web.archive.org/web/20130930190707/http://www.cipa.jp/english/hyoujunka/kikaku/pdf/DC-009-2010_E.pdf |archive-date=September 30, 2013 |df=mdy}}</ref>
<ref name="Livingstone_1998_FAT32X">{{cite magazine |title=FAT-32X may operate differently than FAT-32 on large hard drives |first=Brian |last=Livingston |magazine=[[InfoWorld]] |date=October 28, 1998 |volume=20 |issue=43 |url=http://brianlivingston.com/windowmanager/archive/cgi-bin/new/livingst/981026bl.htm |access-date=2015-04-17 |archive-date=2015-11-12  |archive-url=https://web.archive.org/web/20151112193343/http://brianlivingston.com/windowmanager/archive/cgi-bin/new/livingst/981026bl.htm |url-status=live }}</ref>
<ref name="PowerQuest_1998_FAT32X">{{cite web |title=What is a FAT32X partition? |first=David |last=Steinberg |publisher=[[PowerQuest]] Technical Support |work=Tech Tip / FAQ |date=May 1, 1998 |url=http://www.sysopt.com/showthread.php?88915-What-is-FAT32X&p=532052&viewfull=1#post532052 <!-- another url citing the same source: url=http://www.techimo.com/forum/archive/index.php/t-20617.html --> |access-date=2015-04-17 |archive-date=2015-09-21  |archive-url=https://web.archive.org/web/20150921030455/http://www.sysopt.com/showthread.php?88915-What-is-FAT32X&p=532052&viewfull=1#post532052 |url-status=live }}</ref>
<ref name="PowerQuest_1998_PQ4">{{cite web |title=PowerQuest PartitionMagic 4.0 now available |first=Christina |last=Karpowitz |publisher=[[PowerQuest]] |url=http://www.powerquest.com/press/PM4available.html |date=September 23, 1998 |archive-url=https://web.archive.org/web/19990208204638/http://www.powerquest.com/press/PM4available.html |archive-date=February 8, 1999 |access-date=2015-04-17}}</ref>
<ref name="Caldera_1998_DRFAT32">{{citation |title=DRFAT32.SYS R1.00 INT 13h Interface for FAT32 Redirector |publisher=Caldera, Inc. |date=September 11, 1998}}</ref>
<ref name="Caldera_1998_DRFAT32-RM">{{cite book |title=README.TXT – Caldera DR-DOS FAT32 Enabled Boot Disk (DRFAT32) |publisher=Caldera, Inc. |date=July 24, 1998}}</ref>
<ref name="Duitz_2001_FAQ">{{cite web |title=Can anyone explain FAT32X? |first=Neal |last=Duitz |publisher=Win98 Private FAQ, Windows 98 Consumer Preview Program |url=http://www.win98private.net/fat32x.htm |date=July 17, 2001 |archive-url=https://web.archive.org/web/20040613232209/http://www.win98private.net/fat32x.htm |archive-date=June 13, 2004 |access-date=2015-04-17}}</ref>
<ref name="Costanzo_1998_FAT32X">{{cite web |title=FAT32X |first=Lance |last=Costanzo |url=http://lance.advantweb.com/fat32x/ |date=May 14, 1998 |archive-url=https://web.archive.org/web/19980521015015/http://lance.advantweb.com/fat32x/ |archive-date=May 21, 1998 |access-date=2015-04-17}}</ref>
</references>

== External links ==
* [https://support.microsoft.com/kb/154997/ ''Description of the FAT32 File System'']: Microsoft Knowledge Base Article 154997
* [https://jeffpar.github.io/kbarchive/kb/039/Q39927/ ''MS-DOS: Directory and Subdirectory Limitations'']: Microsoft Knowledge Base Article 39927
* [https://support.microsoft.com/kb/100108/ ''Overview of FAT, HPFS, and NTFS File Systems'']: Microsoft Knowledge Base Article 100108
* Microsoft Technet; [https://web.archive.org/web/20060307082555/http://www.microsoft.com/technet/prodtechnol/winxppro/reskit/c13621675.mspx ''Volume and file size limits of FAT file systems''], copy made by [https://archive.org/ Internet Archive Wayback Machine] of an article with summary of limits in FAT32 which is no longer available on Microsoft website.
* [[Raymond Chen (Microsoft)|Chen, Raymond]]; [https://web.archive.org/web/20081118122857/http://www.microsoft.com/technet/technetmag/issues/2006/07/WindowsConfidential/ ''Microsoft TechNet: A Brief and Incomplete History of FAT32'']
* [https://web.archive.org/web/20170610205053/https://support.microsoft.com/en-us/help/263044/fdisk-does-not-recognize-full-size-of-hard-disks-larger-than-64-gb Fdisk does not recognize full size of hard disks larger than {{nowrap|64 GB}}]: Microsoft Knowledge Base Article 263044, copy made by [https://archive.org/web/ Internet Archive Wayback Machine]. Explains inability to work with extremely large volumes under Windows 95/98.
* [https://web.archive.org/web/20050319235548/http://www.microsoft.com/resources/documentation/Windows/XP/all/reskit/en-us/prkc_fil_cycz.asp ''Microsoft Windows XP: FAT32 File System''], copy made by the [[Internet Archive]]'s [[Wayback Machine]] of an article with summary of limits in FAT32 which is no longer available on Microsoft website.

{{File systems}}
{{Microsoft Windows components}}
{{Ecma International Standards}}
{{ISO standards}}
{{List of International Electrotechnical Commission standards}}

[[Category:1977 software]]
[[Category:Computer file systems]]
[[Category:Disk file systems]]
[[Category:DOS technology]]
[[Category:Ecma standards]]
[[Category:File systems supported by the Linux kernel]]
[[Category:Windows components]]
[[Category:Windows disk file systems]]