Two generic record-permutation bubble devices—the bubble ladder and the bubble string comparator—have been reported in the literature but not yet implemented. The former relies on the extensive use of external control lines, while the latter relies solely on the interaction between bubbles. The ladder has evolved into an odd- even sorter and then a rebound sorter, but, uufortunately, it is operated by a large number of control lines. This paper shows that equally efficient but more versatile sorters can be constructed from the bubble string comparators without the control lines. Moreover, the new sorter—an up-down sorter—will be implemented in the recently invented high-density, high-speed, coil-less perforated-sheet bubble devices.

Bubble latches (switches with memory capability) provide very simple associative-search devices in shift-register type memories. Such devices allow a simple implementation of content-addressable memories (CAM's), only requiring small addition of area, circuits, and interconnections to those of a conventional shift-register memory. Moreover, such devices, in combination with a multi-input or circuit, implements a versatile logic array.

A twistor is an anisotropic ferromagnetic cylindrical wire with nonmagnetic core. The intrinsic magnetization flux curls in helical sense in the wire and has an air return path. Many field problems must be solved for their successful use as information storage elements. For instance, the demagnetizing field in the wire causes instability of storage and therefore must be reduced by suitable geometry of the twistor. The flux lines emanating from a bit link neighboring windings and also impose a magnetic field intensity in neighboring bits. The interactions, although undesirable in packing bits in a memory array, can be used to advantage as operating forces in logical devices.1 This paper analyzes the demagnetizing field in a twistor bit, based on the geometrical model of a confocal hollow prolate spheroid and the magnetic characterization of the material by B = μ0(H+M) where M is the intrinsic magnetization, constant in magnitude, but oriented by the external field. Demagnetizing factors for confocal hollow prolate spheroids are plotted against length-to-diameter ratio and wall thickness. Expressions for field intensities outside a twistor bit are given. Analogies between twistors and thin films are examined.

Thin films of Ni-Fe alloy may be prepared to be anisotropic and exhibit square-loop M-H characteristics. In films that are single-domained with flux changes involving only rotation of intrinsic magnetization controlled by cross-magnetization fields, very fast switching action can be obtained for storage and logic functions. Problems of coupling to the flux changes and interaction in an array of such films require study of the magnetic-field distribution. In the treatment given, a circular, single-domain, thin film is represented by a very flat oblate spheroid. The field distribution outside the spheroid is found by assuming that the magnetic properties are characterized by an intrinsic magnetization M constant in magnitude, but varies in direction depending on field and energy considerations. Calculation of the field distribution is given for a typical film with diameter to thickness ratio of 105. From the regions over which field changes are most significant, conclusions are drawn as to the proper size of sensing loops and spacing to avoid interaction during switching in film arrays.