  Magnetic flux quantization in superconductors allows the implementation of
fast and energy-efficient digital superconducting circuits. However, the
information representation in magnetic flux severely limits their functional
density presenting a long-standing problem. Here we introduce a concept of
superconducting digital circuits that do not utilize magnetic flux and have no
inductors. We argue that neither the use of geometrical nor kinetic inductance
is promising for the deep scaling of superconducting circuits. The key idea of
our approach is the utilization of bistable Josephson junctions allowing the
representation of information in their Josephson energy. Since the proposed
circuits are composed of Josephson junctions only, they can be called
all-Josephson junction (all-JJ) circuits. We present a methodology for the
design of the circuits consisting of conventional and bistable junctions. We
analyze the principles of the circuit functioning, ranging from simple logic
cells and ending with an 8-bit parallel adder. The utilization of bistable
junctions in the all-JJ circuits is promising in the aspects of simplification
of schematics and the decrease of the JJ count leading to space-efficiency.
