Abstract: A rotational positioner for a magnetic disk memory comprises a pedestal constituting a portion of the positioning magnet system and a positioner shaft. In a one-piece pivot member, pivot arms and bracket arms are integrated and disposed in common on a hub. Each pivot arm comprises a device at its free end for releasably receiving a head base plate which carries a pair of magnetic heads by way of a magnetic head mount.

Abstract: Disk surfaces for magnetic disk memories used in data processing systems are smoothened by a burnishing-like device consisting of a circular-cylindrical-shaped body (sliding block) having opposing flat base surfaces with at least one sharp-edged groove positioned on at least one of the base surfaces. This smoothening device is pressed manually or by a support mount similar to a magnetic data-head support mount of a magnetic disk memory against a disk surface while relative motion is provided between the device and the disk whereby the groove edges contact any surface irregularities on a disk surface being smoothened while the flat areas between the groove edges prevent undue disk surface damage.