The use of thin, uniaxially anisotropic, magnetic films in binary-storage cells using the rotational switching system is described briefly. The apparatus used traces out automatically curves of cell output against switching current for switching pulses 6–60ns long. Continuous films on conducting substrates were used and it was found that asymmetries appeared in the curves for the shorter pulses, owing to the field from eddy currents induced in the substrate opposing any changes in the cell setting. However, the curves became symmetrical if the film was in a multidomain state before the cell was set.The experiments also show that the reduction and distortion of the applied fields caused by intersecting conductors can be virtually eliminated by slotting the conductors but that segments ½mm wide are permissible. Contrary to expectation, the drive current required to set the film cells increases with decreasing pulse length (e.g. 1A at 60ns, 2A at 15ns, 5A at 6ns); this effect is only partially explained by substrate eddy currents. The effects of the width of the drive and digit conductors on the required drive currents are explained by the propagation of magnetisation changes away from the edges of the conductor, probably caused by magnetostatic coupling within the film. Also, contrary to expectation, the digit-conductor width was found not to affect the digit current required for widths up to 5mm for films more than 800Å thick. Although this cannot be completely explained by the observed propagation of magnetisation changes, limiting the propagation by using an isolated patch of film produces the expected result that the digit current required to set the cell is proportional to the digit-conductor width.