The principle of operation of existing capacitor readonly memories is explained and their shortcomings pointed out An improved type is described and a mathematical analysis made of the factors that limit its performance. These factors are: a) unwanted coupling between sense lines (“sneak paths”), and b) sense-line distortion caused by losses. For the purpose of the analysis, the memory is reduced to a system consisting of two conductors over a ground plane, the conductors being coupled along their length by a distributed admittance. The transmission characteristics of this system are derived in the Appendix. © 1963 IEEE. All rights reserved.