Distribution Media Format
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 media more difficult. Macintosh running Disk Copy 6.3.3 on Mac OS 7.6 or later 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 VFD image and XDF images are supported by Windows Virtual PC.[4]
See also
- 2M, a program that allows the formatting of high capacity floppy disks
- fdformat, a program that allows the formatting of high capacity floppy disks
- XDF, a high-density diskette format used by IBM
References
- ↑ "Definition of Distribution Media Format (DMF)". Microsoft Knowledge Base. 2007-01-19. Retrieved 2011-10-16.
- ↑ 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 …
- ↑ "Disk Copy 6.3.3". Apple Computer, Inc. 1999. Retrieved 2016-04-27.
- ↑ 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.