Abstract: A magnetic head for writing and/or reading information in mutually parallel tracks of a magnetic recording medium includes a transducing gap having a depth of the same order of magnitude as the longest wavelength on the recording medium. The gap also has a slope of less than or equal to 45.degree. relative to the head surface which faces the medium.

Abstract: A device for determining a complete track number of a track which forms part of a set of tracks on a disc-shaped record carrier, enabling direct control by means signals detected from servo sectors during each phase of positioning, and making a calculated estimate of a new track number on the basis of the displacement speed of the positioning member. The device reads a first track number in the group and estimates a second group number. It then estimates a complete track number on the basis of the displacement speed of positioning member body, determining the difference between the complete track number read and the estimated complete track number and comparing the magnitude of the difference obtained with a value determined by half a signal being produced if said magnitude is smaller than half, said signal validating the complete track number present in the first determination. A complete track number is determined by the sequential use of said estimates after each servo sector.

Abstract: A magnetic disc memory having a device for positioning a magnetic head on a track. A disc is sub-divided into sectors comprising groups of data tracks and, alternating therewith, sectors having groups of servo tracks which define the data tracks which are staggered over one half track pitch with respect thereto. Each servo track includes magnetization changes (reference transitions) for reference purposes. Magnetization changes for position detection purposes (measuring transitions) are present in the servo sectors, stepwise from track to track per group of servo tracks. Said stepwise magnetization changes are of alternating polarity from track to track. An additional transition is provided every other servo track in the vicinity of the reference transitions. A stepwise organization of the magnetization changes in two longitudinal directions of the servo tracks enables the number of tracks per group to be substantially doubled.