Distribution Media Format

Distribution Media Format (DMF) is a format for floppy disks that Microsoft used to distribute software. It allowed the disk to contain 1680 KiB of data on a 31⁄2-inch disk, instead of the standard 1440 KiB. As a side effect, utilities had to specifically support the format in order to read and write the disks, which made copying of products distributed on this data storage medium more difficult. An Apple Macintosh computer running Disk Copy 6.3.3 on Mac OS 7.6 or later can copy and make DMF disks. 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 standard 1440 KiB and DMF 31⁄2-inch diskettes:

Feature Standard DMF
Tracks 80 80
Sectors per track 18 21
Cluster size, in bytes 512 1024 or 2048
Root directory entries 224 16

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

See also

References

  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. ↑ Rosch, Winn L. (1997-04-18). Floppy Disks. 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 ... {{cite book}}: |work= ignored (help)
  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. Archived from the original on 2017-08-26. Retrieved 2011-10-16.