A family of logic circuits using nonhysteretic superconducting quantum interference devices (SQUIDs) connected together to perform various functions using a common operating principle. Each circuit has an output line, first and second power supply lines having first and second voltage states, and input lines that can have one of the two voltage states. A pull-up circuit, having at least one SQUID, is connected between the output line and the first power supply line, and the input lines are coupled to the pull-up circuit in such a manner as to pull the output line to the first voltage state only if the input lines conform with a selected combination of voltage states. A pull-down circuit, also having at least one SQUID, is connected between the output line and the second power supply line, to pull the output line to the second voltage state only when input lines do not conform with the selected combination of voltage states. A single configuration of SQUIDs can be connected to perform any of six different basic Boolean logic functions on signals applied to the input lines. Additional SQUIDs allow the performance of more complex logic functions. A slightly different arrangement of SQUIDs operates as a two-port random access memory cell.