Abstract: Multiple (e.g. 500) ultra-thin flexible storage disks are stacked in a closely spaced configuration between circular end plates and arranged for rotation together with the plates about a common axis. Recording surfaces of the rotating disks are deflected to successively expand (open) and contract (close) a selected interface and thereby provide recording access at the expanded interface. Separation of the selected interfacing surfaces for access is facilitated by maintaining a predetermined air pressure between the contracted disks which conditions the rotation of the disks to bistability in the contracted position. Thus only a small initiating force is required to expand any selected interface with the disks initially contracted. This reduces disk wear. Expansion of a selected interface is accelerated (for shortening access time) by applying vacuum to the disks in synchronism with the initiating force.

Abstract: A disc storage file includes a multiplicity of closely spaced continuously rotating flexible or floppy discs associated with an accessing assembly for spreading the discs apart at randomly selected positions to accommodate a magnetic head. Apparatus for locating the disc interface (gap) to be accessed includes a pair of offset photocells which are light coupled to the disc gaps. The light applied to the photocells is guided in offset channels of a shroud and shaped congruent to the photocell surfaces by offset fiber optic shaping arrays. The offset arrays and associated electronics allow for accurate counting of gaps in the presence of fluctuating disc motion in the axial direction.