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List of floppy disk formats

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List of floppy disk formats
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This is a list of different floppy disk formats.

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8-inch, 5+14-inch, and 3+12-inch floppy disks

Physical formats

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Logical formats

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Throughout the 1970s and 1980s, many different logical disk formats were used, depending on the hardware platform.

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https://www.c64-wiki.com/wiki/Commodore_1571

https://vintagecomputer.ca/files/Commodore/C900/C900%20Floppy%20Specification.pdf

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See also

  • Zip drive (floppy-like, but incompatible medium using different technology)
  • PocketZip (floppy-like, but incompatible medium using different technology)
  • SuperDisk (floppy-like with drives also compatible with 3.5" floppy disks)
  • Magneto-optical drive (floppy-like, but incompatible medium using different technology)

Notes

  1. Custom controller with unique track layout.
  2. 16 sector filesystems require a compatible disk controller (PROM update) and Apple DOS 3.3 or later.
  3. Apple II double-density 312-inch (90 mm) drives use variable sectors sizes (tracks 00-15: 12 sectors, tracks 16-31: 11 sectors, tracks 32-47: 10 sectors, tracks 48-63: 9 sectors, tracks 64-79: 8 sectors), 394 rpm to 590 rpm.
  4. Apple II high-density 312-inch (90 mm) drives require a compatible disk controller and ProDOS 8.
  5. Third party drives offer up to 1440 KB.
  6. Commodore floppy drives used a fixed rotation speed with variable sector density (see: Zone bit recording).
  7. This format was used by the Amiga 1020 external floppy drive and some third-party drives connected to the normal Amiga floppy drive bus.
  8. Though the Amiga used MFM, the format places sectors too close together for a standard IBM PC compatible floppy disk controller to read (appearing as one 5632-byte physical sector per track).
  9. Format used by rare third-party drives with quad density disks; such drives were usually switchable between 80-track and 40-track (A1520/PC-compatible) operation.
  10. Format used by third-party gcrdisk.device driver in order to use PC-standard HD floppy drives (which rotated at a fixed 300 rpm) via the Amiga floppy drive bus. The Amiga's floppy controller could not keep up with the data rate needed for MFM recording on HD floppies without reducing rotational speed, so the third party driver used an alternate GCR mode.
  11. The calculated formatted capacity is based on FAT12 format.
  12. While IBM didn't include an 8-inch floppy drive option on any of their PCs and PC DOS, MS-DOS 1.25 supported 8-inch disks and added support for higher capacities in version 2.0. MS-DOS' predecessor 86-DOS used 8-inch diskettes as well.
  13. Rare format appearing on some early PC/XT clones using quad-density disks.
  14. These variations are known as DMF diskettes, used for a time to pack more data on to each disk for software distribution.
  15. Inner 3 tracks of 8 sectors/track format are unused.
  16. The PC98 312-inch (90 mm) formats are also known as "3 Mode" floppy disks, usable on IBM PC compatibles with a 3-mode floppy drive.
  17. The two sides are managed as two independent 160 KB disks
  18. The two sides are managed as two independent 320 KB disks
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    References

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