hard-sectored
Hard sectoring is a relic of floppy disks. Here, a small punched hole in the floppy disk and in the floppy disk case provided the initial marking of the sectors.
When the floppy disk was rotated, the punched out hole for hard sectoring was detected by an optical device that had the function of a light barrier and generated a corresponding reference signal. All sectors referred to this signal. The hard sectoring technique is no longer used today. Today's media, hard disks, DVDs and floppy disks are soft-sectored, i.e. magnetic. The earlier 8" floppy disks had a whole row of index holes on their periphery.