Word selection by integrated magnetic needles in the 107-bit THEMIS store

Word currents in the batch fabricated THEMIS store are supplied by magnetic selection needles closely integrated with the storage elements. The selection needle behaves like the well-known switch core. The word current generated is a function of many parameters and tolerances because of interactions between the storage elements and selection needles. This paper discusses these interactions in detail and describes the needle-stack construction which led to well-defined word currents. It also gives results of full- and half-selection current measurements on two 256-plane stacks.