Abstract: In a disc data store for the storage of retrievable informational data in a plurality of concentric circular data storage tracks on a rotary medium accessed by a positioner operable to respond to a track command signal to place a data recording or recovering transducer into adjacence with a selected track where a disc rotator is operable to maintain the surface velocity of the medium beneath the transducer substantially constant regardlessly of the radius of the transducer on the medium for the purpose of maximizing the data storage capacity of the medium, the sluggishness of response of the angular velocity of the medium found in those systems where a position transducer senses the position of the recording or recovering transducer to provide an output for controlling the angular velocity of the medium is overcome by providing that the medium is rotated by an angular velocity control servomechanism operable to respond to the same track command signal as received by the positioner to so maintain the surface v

Abstract: A disc file, for the storage of retrievable, informational data in a plurality of concentric, data storage tracks, on a disc rotating at a constant angular velocity, comprises a radially mobile head 44 for data recording or recovery on the disc, a head positioner for positioning the head to interact with selectable tracks on the disc and a variable frequency clock generator for providing data recording or data recovery control signals whose rate of repetition is a linearly increasing continuous function of the radius of interaction of the head with the disc.