Editing File Allocation Table (section)

== 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>