Editing IBM Extended Density Format

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The '''[[IBM]] eXtended Density Format''' ('''XDF''') is a way of [[superformatting]] standard high-density 3½-inch and 5¼-inch [[floppy disk]]s to larger-than-standard capacities. It is supported natively by IBM's [[PC DOS]] versions 7 and 2000 and by [[OS/2]] Warp&nbsp;3 onward, using the XDF and XDFCOPY commands (directly in OS/2).

When formatted as XDF disks, 3½-inch floppies can hold 1860&nbsp;<abbr title="1024 bytes">KiB</abbr>, and 5¼-inch floppies can hold 1540&nbsp;KiB, using different number of sectors as well as different sector size per track (not all sectors in the same track are of the same size).

However, the first cylinder uses standard formatting, providing a small [[FAT12]] section that can be accessed without XDF support and on which can be put a [[README|ReadMe file]] or the XDF drivers. Floppy distributions of OS/2 3.0, PC DOS 7 and onward used XDF formatting for most of the media set. Floppy disks formatted using XDF can only be read in floppy disk drives that are attached directly to the system by way of an [[Floppy disk controller|FDC]]. Thus, [[USB]] attached floppy drives cannot read XDF formatted media.

== See also ==
* [[fdformat]], a program that allows the formatting of high capacity floppy disks
* [[Distribution Media Format|DMF]], a high-density diskette format used by Microsoft
* [[FD32MB]], technically unrelated special HD floppy format supported by [[LS-240]] SuperDisc drives also providing a traditionally formatted mini file system containing only a [[README]] file
{{Portal|Engineering}}

[[Category:IBM storage devices]]
[[Category:Floppy disk computer storage]]

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