A theoretical model for the calculation of the density of domain walls at remanence during hard axis switching in thin films is presented. Demagnetizing energy is taken into account, and the model predicts a point at which a lockedin state will occur. An introduction to the theory and operation of thin film parametrons is presented. Three new controlled wall-motion shift register designs are described, all of which are characterized by an easy-axis direction that is perpendicular to the direction of wall propagation, resulting in the possibility of high information density and high speed of operation. Descriptions are given of a fast thin film readout scheme, a thin film analog-to-digital converter, and a new shift register concept.