DMF

11/18/2000

Distributed Media Format (DMF): A floppy disk format devised by Microsoft in the mid 1990s in order to reduce the number floppy disks required to distribute products such as Windows95 and Microsoft Office. The disks are formatted with 21 512 byte sectors per track instead of the more normal 18 and thus hold 1.68Mb instead of the normal 1.44. There may be several different formats and significant problems were reported in writing files to the disks.

The disks apparently use interleaved records with very short inter-record gaps in order to fit as much data as possible onto the disks. The interrecord interval would not be enough to allow CRC computation and other housekeeping, so alternate records would have to be skipped. That would result in the disk requiring two rotations to read/write a track.

While the disks can be read in most floppy drives, they will not work in floptical drives. Macintoshes can read the disks, but can not format them. Linux can reportedly read and write them using dev fd0H1740.