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# Logical Circuits

IP.com Disclosure Number: IPCOM000097697D
Original Publication Date: 1961-Apr-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 31K

IBM

## Related People

Sanborn, JL: AUTHOR

## Abstract

Multiple control cryotrons in which the state of the gate conductor is determined by the vector addition of applied magnetic fields provide logical circuits. Each multiple control cryotron has a plurality of control conductors. These apply magnetic fields to the gate conductor. They are so arranged that equal magnitudes of current flow through any control conductor apply equal magnetic fields to the associated gate. Further, when the current flow is equal but opposite in direction through a pair of controls, equal magnetic fields of opposite polarity are generated. This results in the net field applied to the gate being essentially zero.

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Logical Circuits

Multiple control cryotrons in which the state of the gate conductor is determined by the vector addition of applied magnetic fields provide logical circuits. Each multiple control cryotron has a plurality of control conductors. These apply magnetic fields to the gate conductor. They are so arranged that equal magnitudes of current flow through any control conductor apply equal magnetic fields to the associated gate. Further, when the current flow is equal but opposite in direction through a pair of controls, equal magnetic fields of opposite polarity are generated. This results in the net field applied to the gate being essentially zero. The characteristics of the cryotrons used are such that, with the incremental currents applied to the controls adjusted to generate integral units of magnetic fields, the vector addition of 1 does not introduce resistance in a gate carrying 1 unit of current. Also, a vector addition of 2 introduces resistance in a gate carrying zero current.

For circuit operation, the presence of a variable of the function is indicated by current flow (direction shown by the arrows) sufficient to generate 1 unit of magnetic field. Conversely, the absence of a variable results in no current flow. Additionally, biasing currents are continuously applied to selected controls to generate magnetic fields of 1, 2 or 3 units of magnetic fields as indicated. By way of example, consider the circuit to generate the logical function f = AB.

The upper cryotron with three controls has a biasing current in a downward direction, This generates three units of magnetic field to maintain the gate normally resistive in the absence of the applied variables. Conversely, the lower cryotron has no biasing current....