Abstract: A magnetic transducer for use with a flexible disk and having inner and outer portions of respectively less and greater convex sphericity providing a central spherical surface zone within a surrounding spherical surface zone. The magnetic gap is centrally located in the central surface zone. The radius for the outer portion has a center on the center line of the transducer, and the center of curvature of the inner portion is spaced from the center line of the transducer in the direction of motion of the disk across the transducer so that most of the central zone faces the direction of disk movement.

Abstract: A mechanism for moving an access arm carrying a magnetic transducer into the most appropriate position between pairs of consecutive flexible disks in a rotatable disk stack to assure that the proper disk is thereby accessed. The mechanism includes mechanism for preliminarily accessing each of the disks with a plurality of steps between consecutive disks in the stack and filling a position register with a unique identification number from each disk and with numbers of the steps corresponding to each of the disk numbers and mechanism for averaging the step numbers corresponding to each of the disks and placing the average step number in an access table to correspond with each of the disk numbers so that the access arm may be stepped to the step number listed for each of the disks in the access table for a reading or writing action using the transducer.

Abstract: A magnetic storage device having a stack of spaced flexible magnetic disks and an access arm carrying a magnetic transducer moveable between adjacent disks in the stack for accessing the disk surfaces. The access arm is blunt on one side edge and is sharp on the other side edge and increases gradually in thickness from the sharp edge to a position of maximum arm thickness adjacent the blunt edge at which the magnetic transducer is embedded in the arm. The disks rotate so as to move across the arm from the sharp edge toward the blunt edge, and the disks thus closely follow the surfaces of the access arm and particularly the surface of the transducer.

Abstract: A magnetic disk, particularly of the thin flexible type, has a magnetic head traversing the disk in order to come into registry with various concentric tracks on the disk. An electric motor of the stepping type is mechanically connected with the head for so moving the head, and a "present track number" counter is so electrically connected with the stepping motor as to keep track of the particular magnetic track on which the head is located. On a certain contingency, such as a cessation of power to the system, the circuitry includes components so connected as to cause the stepping motor to move the magnetic head to an outer limit on the disk, outwardly of a prerecorded reference track on the disk. When this point is reached, a switch is actuated by the movement of the head, and connected circuitry causes the head to move back onto the reference track.