Abstract: A coupling for driving a magnetic tape reel uses the interface between a flat surface on the coupling and datum pads on the reel to locate the reel. The coupling includes a drive ring with ring teeth located around a drive shaft. The ring teeth engage mating teeth on the tape reel. The coupling also includes a datum ring having an annular surface located about the drive shaft. The annular surface contacts datum pads on the tape reel to axially position the tape reel relative to the drive shaft.

Abstract: A thin-film magnetic recording playback head is disclosed wherein mechanically coupled films of a magnetostrictive material and of a piezoelectric material are deposited on a substrate together with a solid state amplifier which is coupled to the piezoelectric film. In operation, localized magnetic patterns on a recording medium induce stress in the magnetostrictive film, which in turn induces in the piezoelectric film a corresponding electrical polarization of non-equilibrium charge density, having a potential associated therewith which is applied to the solid state amplifier.