Abstract: An apparatus for positionally controlling the movable head assembly of a magnetic disc memory unit. In a first state, the head assembly is accelerated under substantially free conditions. In a second or deceleration state, the assembly speed is compared with and regulated by a series of theoretical speeds set in accordance with the actual speed attained by the movable head assembly during the first state.

Abstract: A device for the precise positioning of a movable member includes means for generating signals permitting localization of successive stop positions of the moving member and means for generating a pulse whenever the member approaches any stop position within a distance that equals a given fraction of the distance between two successive positions; when the member approaches a prescribed stop position, the relevant pulse ensures the enablement of a circuit that controls the precise stopping of the member. The device is particularly useful for setting a magnetic head on a given track of a magnetic disc.