Abstract: The invention provides a simply constructed magnetic disk device with a head lift system that can improve reliability and reduce costs. A head arm is integrated with a rigid base section, a spring, and a rigid tip. A magnetic head is fixed to the tip of a head holder. A contact section of a lateral bar form is formed in the tip, which is normally kept away from the under surface of the head holder so that it will not make contact. When the tip is lifted, however, the contact section contacts the under surface of the head holder and lifts it together. To contact with the pin fixed on the tip of the tip, a cam is engraved and formed on part of a cover plate. The cam consists of a plane section, an inclined section which ascends to the left in the figure, and a semi-circular concave section into which the pin can be fitted, thus forming a contour face.

Abstract: A disc storage unit includes discs having surfaces with concentric tracks for storing data in sectors. Each sector has identification information including a physical address designating a particular disc surface, sector and track. The physical addresses are contiguous for one surface to another at a first or last sector in a radially outermost or innermost track, respectively. Heads are provided for reading and writing data from and onto the discs. The position of each head within a track is determined using servo information recorded between adjacent sectors. Address converting circuitry converts logical addresses from an external computer into physical addresses on the discs, including physical addresses which span a plurality of tracks located on both surfaces of a disc, when reading or writing data at logical addresses is commanded. Head selecting circuitry responds to the physical addresses by selecting each head corresponding to a surface of the disc on which the physical addresses are located.