Various embodiments of the present invention are directed to crossbar-memory systems to methods for writing information to and reading information stored in such systems. In one embodiment of the present invention, a crossbar-memory system (800) comprises a first layer of microscale signal lines (808), a second layer of microscale signal lines '(810), a first layer of nanowires (804) configured so that each first layer, nanowire overlaps each first layer microscale signal line (808), and a second layer of nanowires (806) configured so that each second layer nanowire overlaps each second layer microscale signal line (810) and overlaps each first layer nanowire (804). The crossbar-memory system includes nonlinear-tunneling resistors configured to selectively connect first layer nanowires (804) to first layer microscale signal lines (808) and to selectively connect second layer nanowires (806) to second layer microscale signal lines (810). The crossbar-memory system (800) also includes nonlinear tunneling-hysteretic resistors configured to connect each first layer nanowire to each second layer nanowire. at each crossbar intersection.