Conventional magnetic technologies allow an extensive trade-off, in computer storage systems, of total capacity, access time to data and price. In the area of "mass" memories significant improvements in capacity and access time are needed that cannot be obtained using inductive recording. That technology is limited by the dimensional factors that can be achieved mechanically and the frequency response of the transducer materials. The substitution of optical transducers relieves both of these limitations so that order-of-magnitude improvements are possible. This paper includes a discussion of the computer needs, the limitations of inductive recording and an illustration in a specific product configuration of the improvement possible by the substitution of a particular magneto-optic approach. © 1970 The American Institute of Physics.