A three-terminal network consisting of two matched tunnel diodes and a fixed resistor is introduced as a basic element for performing peak threshold summation logic. The characteristic between two terminals resembles a tunnel diode curve where application of a signal or bias current to the third terminal causes reduction of the observed peak current. Decrease of this peak current below a fixed load line allows switching from the low- to the high-voltage state for logic-function circuit operation. Such bias-controlled tunnel pairs are shown to be unilateral to a considerable extent (30 db). This is advantageous in logic networks since it allows directional flow of information without the provision of multiphase power supplies or backward diodes, as needed in conventional tunnel diode logic circuits to eliminate back-switching. Circuits are described based on this principle, consisting entirely of tunnel junctions and resistors, for performing OR, MAJORITY, AND and NOR logic. Generalized design equations for circuits with a fan-in of M and a fan-out of N are derived. Test circuits based upon the generalized equations with a fan-in of 9 and a fan-out of 5 were found to operate over a temperature range from -70° to +60°C. A sample switching speed measurement for an OR gate using 1-ma tunnel diodes and a normal degree of drive showed a 7.5-nsec rise time which was triple that observed with a single tunnel diode under similar conditions.

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.