The direct current flux parametron using Josephson junction and based on the principle of parametron seems to be the answer for the search of new technology for the future needs of computer power. The combination of its very high switching speed and highly integrable Josephson junction with the established parametron computer technology accounts for its high performance. This book presents the new type of Josephson computer technology which is fundamentally different from the conventional approach. In this approach, a logic state is represented by a flux polarity whereas the conventional approach uses a voltage state to represent a logic state.