Note that Microsoft enforces a limit of 16 entries in the root directory of a DMF disk by only allocating a single cluster to service as the root, so DMF-formatted disks usually use a subdirectory structure for their contents. However, several special utilities are available for copying and even creating DMF disks. In any case, you cannot write to DMF disks using ordinary software. ![]() In fact, Microsoft called DMF a read-only format. The small interrecord gap made DMF disks difficult to write to with normal floppy disk drives. The DMF format also skewed the sectors on adjacent tracks by three sectors so that Sector 1 on Track 4 sat next to Sector 1 on Track 2. This interleaving resulted in slower reading because the disk had to spin around twice for each track to be read. Each track used a 2:1 interleave factor so that sectors did not appear in order. DMF squeezed more sectors on each track by reducing the interrecord gap (the space between sectors) down to nine bytes. The DMF format differed from the standard format in that it used 21 sectors per track instead of the normal 18. This variation in the high-density design allowed Microsoft to fit 1,720,320 bytes on a standard high-density 3.5-inch floppy disk in place of the more normal 1,474,560 bytes (nominal 1.44MB). ![]() ![]() The leading extra-capacity alternative was Microsoft's Distribution Media Format (DMF). Rosch:īefore CD-ROM media took over the job of program distribution, software publishers sought and developed ways of shoehorning more data onto every floppy disk. I found a very important quote in the Hardware Bible, 6th ed., by Winn L.
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