The magnetic tape (8) is guided in the conventional manner from a first reel hub over a deflection pulley to the recording or playback zone and from there over a further deflection pulley (21) to the second reel hub. In each cassette part between the recording or playback zone and the reel hub, a U-shaped tape clamp (25) is placed onto the magnetic tape (8). A slide (74) is provided with two spaced stops (81, 82) for the tape clamp (25), which stops, in one position of the slide (74), firmly hold the tape clamp, without hindering the magnetic tape (8) (normal operation). In the other position of the slide (74), the tape clamp (25) runs with the magnetic tape (8) onto the reel hub in the case of forward-winding or, in the case of re-winding, the tape clamp runs into the gap formed by a fixed projection (73) on the housing and a surface (83) of the slide (74), where it is pressed together and stops the magnetic tape (8) (memory operation). By actuating the slide (74) at any desired selected point of the magnetic tape (8) and after subsequent forward-winding the later re-winding can be automatically stopped at the selected point.