A detailed optimized design of a 1 K‐bit memory cell array with drivers and reset gates has been carried out based upon a set of projections for achievable tolerances in linewidths, resistances, and Josephson critical currents in a 2.5‐&mgr;m technology employing niobium edge junctions. The cell operating regions were significantly widened relative to a predecessor Pb‐alloy design by adjusting gate and cell inductances, adjusting current levels, and by employing a different timing sequence for application of write controls. Much‐improved control of array‐line current oscillations, without loss of speed, was achieved by employing a distributed filtering scheme using distributed damping. The design employs trimming of currents to accommodate ±8% chip‐to‐chip differences in the average critical current. The cell size is 63×63 &mgr;m. Monte Carlo calculations of threshold curve tolerances and operating current sensitivities and tolerances lead to a design‐limited yield of about 95% for 4 K bits.