High-speed characteristics of laminated ferrite memory planes

The high packing density, low digit current, and partial switching mode characteristics of laminated (monolithic) ferrite memory planes make high-speed operation of the planes attractive. High-speed test data concerning switching time, back voltage, sense signal, and temperature effects are presented for ferrite laminates containing 64 by 64 conductors, spaced 15 mils between centers. Laminates of two ferrite compositions, Mg-Mn-Zn and Mg-Mn, were evaluated. The Mg-Mn laminates exhibit superior disturbed sense signals and temperature characteristics. The Mg-Mn laminates are operable at a continuous 8-MHz rate without heat sinking. Maximum sense signals are obtained using digit current pulses exceeding write current pulses in duration; nonreturn-to-zero digiting is suggested for fully utilizing this characteristic.