Distribution Media Format

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Distribution Media Format (DMF) is a format for floppy disks that Microsoft used to distribute software.[1][2] 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 disks, which made copying of products distributed on this medium more difficult. An Apple Macintosh computer running Disk Copy 6.3.3 on the Mac OS 7.6 or later operating system can copy and make DMF disks.[3] The first Microsoft software product that uses DMF for distribution were the "c" revisions of Office 4.x. It also was the first software product to use CAB files, then called "Diamond".

Comparison of DMF and standard 1440 kB 3½-inch diskettes:

1440 kB DMF
Tracks 80 80
Sectors per track 18 21
Cluster size 512 bytes 1024 or 2048 bytes
Root directory entries 224 16

DMF in the form of a 1680 kB Virtual Floppy Disk (VFD) image and IBM Extended Density Format (XDF) images are supported by Windows Virtual PC.[4]

See also[edit]

  • 2M, a program that allows the formatting of high-capacity floppy disks
  • fdformat, a DOS program that allows the formatting of high-capacity floppy disks
  • HDCopy, a DOS program that can read and write floppy disk and disk images in multiple formats, including DMF
  • IBM Extended Density Format (XDF), a high-density diskette format used by IBM


  1. ^ "Definition of Distribution Media Format (DMF)". Microsoft Knowledge Base. 2007-01-19. Archived from the original on 2011-09-14. Retrieved 2011-10-16.
  2. ^ Winn L. Rosch (1997-04-18). "Floppy Disks". Hardware Bible 1997. SAMS Publishing. ISBN 0-672-30954-8. Retrieved 2011-10-16. ... reducing the inter-record gap (the space between sectors) down to nine bytes ... Each track uses a 2:1 interleave factor ... The DMF format also skews the sectors on adjacent tracks by three sectors ...
  3. ^ "Disk Copy 6.3.3". Apple Computer, Inc. 1999. Retrieved 2016-04-27.
  4. ^ Armstrong, Ben (2007-01-05). "Floppy disk image formats supported by Virtual PC and Virtual Server". Virtual PC Guy's Blog. Microsoft. Retrieved 2011-10-16.

External links[edit]