Design and operation of a Quantum Flux Parametron bit-slice ALU

The design of Quantum Flux Parametron (QFP) majority logic circuits presents a number of unique constraints. For example, interconnects must be kept short and have a common small inductance. The former suggests that the bit-slice architecture is well suited to QFP circuits. In order to test this conjecture, a suitably complex logic circuit was designed and a small part of it was fabricated. A design for a 16-function bit-slice arithmetic-logic unit (ALU) was found that satisfied the constraints. It can compute on n-bit operands in 2n+4 QFP stages. A reduced version of the bit-slice ALU cell, containing 30 QFP's, was fabricated and successfully tested at low speed. The design experience showed that complex combinatorial QFP logic circuits are possible. Larger circuits will be feasible with computer-aided tools.<
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