Abstract: Method and apparatus for opening stacked disk memory members arranged in a pack for co-rotation and having substantial freedom of axial movement relative to one another, the opening being accomplished by engaging the disk pack with drive means having axially extending pins of varying length, and of a predetermined pattern with the increments of pin length variation being substantially equal to the desired openings between the disk members, and the disk memory members having openings defined therein with corresponding patterns adjacent disk memory members having progressively fewer openings to receive pins of a predetermined pattern with the result that all pins of a predetermined length bear upon a disk memory member and axially separate it from the adjacent disk memory member, thereby providing an opening at the termini of each set of pins of common length.