A new and powerful method has been developed which makes possible an analytical study of the sensitivity of 2D memory cycle times to most of the pertinent memory variables. Worst-case conditions in a 2D ferrite core memory have been considered. The analysis allows independent variations (from nominal) of all drive pulse amplitudes and widths, plus variations in the thresholds of the cores caused by manufacturing. Also included are the efficiency of the thermal packaging and the effects of partial switching. In the analysis, the nonmagnetic times (time for regeneration, array delays, etc.) are lumped into a single nonmagnetic delay time. The analysis results in a set of simultaneous equations interrelating all the pertinent memory variables. A set of characteristic curves is determined experimentally for the particular core type being evaluated. From these curves, 18 constants, which allow the various core properties to be analytically described, are extracted. The simultaneous equations were programmed for machine solution so that, upon the injection of 18 core constants, the speed capabilities of that particular core type could be fully evaluated in about one minute. This technique allows the core to pick its own nominal operating current amplitudes and durations. This is important since, otherwise, there is no way of being sure that the pulses picked for a core at ambient temperature will be satisfactory when the core runs hot in a worst-case cycle. The results found when applying this new method to high-speed 2D ferrite memory cores are included. © 1965, IEEE. All rights reserved.