Hard sectoring

In older 8- and 5¼-inch floppy disks, hard sectoring was implemented by punching "sector holes" in the disk to mark the start of each sector. These were equally spaced holes, at a common radius. This was in addition to the "index hole", situated between two sector holes, to mark the start of the entire "track" of sectors. When the index or sector hole was recognized by an optical sensor, a sector signal was generated. Timing electronics or software would use the faster timing of the index hole between sector holes, to generate an index signal.

References

• Federal Standard 1037C