IBM Extended Density Format
Encyclopedia
The IBM
eXtended Density Format (XDF) is a way of formatting standard high-density 3.5" and 5.25" 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 3 onward, using the XDF and XDFCOPY commands (directly in OS/2).
When formatted as XDF disks, 3.5" floppies can hold 1860 KB, and 5.25" floppies can hold 1540 KB, 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 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 a FDC
. Thus, USB attached floppy drives cannot read XDF formatted media.
IBM
International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...
eXtended Density Format (XDF) is a way of formatting standard high-density 3.5" and 5.25" floppy disk
Floppy disk
A floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles...
s to larger-than-standard capacities. It is supported natively by IBM's PC-DOS
PC-DOS
IBM PC DOS is a DOS system for the IBM Personal Computer and compatibles, manufactured and sold by IBM from the 1980s to the 2000s....
versions 7 and 2000 and by OS/2
OS/2
OS/2 is a computer operating system, initially created by Microsoft and IBM, then later developed by IBM exclusively. The name stands for "Operating System/2," because it was introduced as part of the same generation change release as IBM's "Personal System/2 " line of second-generation personal...
Warp 3 onward, using the XDF and XDFCOPY commands (directly in OS/2).
When formatted as XDF disks, 3.5" floppies can hold 1860 KB, and 5.25" floppies can hold 1540 KB, 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 file
README
A readme file contains information about other files in a directory or archive and is commonly distributed with computer software. Such a file is usually a text file called README.TXT, README.1ST, READ.ME, or simply README, although some Microsoft Windows software may occasionally include a...
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 a FDC
Floppy disk controller
A floppy disk controller is a special-purpose chip and associated disk controller circuitry that directs and controls reading from and writing to a computer's floppy disk drive . This article contains concepts common to FDCs based on the NEC µPD765 and Intel 8072A or 82072A and their descendants,...
. Thus, USB attached floppy drives cannot read XDF formatted media.
See also
- 2M2M (DOS)2M is a DOS program by the Spanish programmer Ciriaco García de Celis. It enables higher than normal capacity formatting of floppy disks. It saw active development from 1993 to 1995. The last version, v3.0, was released on March 6, 1995. It was written in C and assembler and compiled using Borland...
, a program that allows the formatting of high capacity floppy disks - fdformatFdformatFdformat is the name of two unrelated programs:* A command-line tool for Linux that "low-level formats" a floppy disk.* A DOS tool written in Pascal by Christoph H. Hochstätter that allows users to format floppy disks to a higher than usual density, enabling the user to store up to 300 kilobytes...
, a program that allows the formatting of high capacity floppy disks - DMFDistribution Media FormatDistribution Media Format is a format for floppy disks that Microsoft used to distribute software. It allowed the disk to contain 1680 KB of data on a 3½-inch disk, instead of the standard 1440 KB. As a side effect, utilities had to specially support the format in order to read and write the...
, a high-density diskette format used by Microsoft