ACCESS TO FLOPPY DISK STACK

摘要

ACCESS TO FLOPPY DISK STACK A method and associated apparatus for positioning an auto-sustaining split precisely and quickly in a rotating stack of floppy type storage disks. Such split permits access to otherwise inaccessible storage surfaces facing the split and constrains these surfaces to circumferentially uniform rotational paths suitable for highest density storage. The ventilation pressure between the disks is set initially to a level above the threshold for formation of the autosustaining split. An externally transported air nozzle, positioned initially to estimated (coarse) coincidence with an axial component of a target cylindrical address, emits a pulsed jet of air into an aligned interface. This forms a partial split having a circumferentially irregular shape inappropriate for storage transducing access. The partial split forms more quickly than the auto-sustainable split and provides a wide relatively unvarying positional reference, by comparison to an unsplit interface. The partial split is thereby useful for precisely determining the displacement between said split and the target interface position. If a null displacement is detected the partial split is transformed into the auto-sustaining configuration by reduction of the ventilation pressure. Otherwise, the partial split is repositioned in small corrective increments, in the appropriate direction for nullifying the displacement, and the displacement is redetermined. The time required to form a partial split is much less than the time required to form an auto-sustaining split, and the average increment of access delay due to the corrective repositioning of the partial split is also relatively small. Progressively differentiable indicia on Successive disk edges facilitate determination of the split displacement.