Model V

The Model V was among the early electromechanical general purpose computers, designed by George Stibitz and built by Bell Telephone Laboratories, operational in 1946.
Only two machines were built: first one was installed at National Advisory Committee for Aeronautics (NACA, later NASA), the second (1947) at the US Army’s Ballistic Research Laboratory (BRL).
Construction.
Design was started in 1944. The tape-controlled (Harvard architecture) machine had two (design allowed for a total of six) processors ("computers") that could operate independently, an early form of multiprocessing.
Weighed about .
Model VI.
Built and used internally by Bell Telephone Laboratories, operational in 1949.
Simplified version of the Model V (only one processor, about half the relays) but with several improvements, including one of the earliest use of the microcode.