Figure 4: The Hopkins Beast: Built in the early 1960s, using dozens of transistors, the Johns Hopkins University Applied Physics Lab's "Beast" wandered white hallways, centering by sonar, until its batteries ran low. Then it would seek black wall outlets with special photocell optics, and plug itself in by feel with its special recharging arm. After feeding, it would resume patrolling. Much more complex than Elsie, its deliberate behavior can be compared to a nucleated single-cell organism like a paramecium or amoeba.