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).

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.

The Model V weighed about 10 short tons (9.1 t).

• Inspired Richard Hamming to investigate the automatic error-correction, which led to invention of Hamming codes
• One of the early electromechanical general purpose computers
• First American machine and first George Stibitz design to use floating-point arithmetic
• Had an early form of multiprocessing
• Had a very primitive form of an operating system, albeit in hardware. A separate hardware control unit existed to direct the sequence of computer operations.

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.

• Research, United States Office of Naval (1953). A survey of automatic digital computers. Models V and VI. Office of Naval Research, Dept. of the Navy. pp. 9–10 (in reader: 15–16).
• "The relay computers at Bell Labs : those were the machines, part 2". Datamation. The relay computers at Bell Labs : those were the machines, parts 1 and 2 | 102724647 | Computer History Museum. part 2: pp. 47, 49. May 1967.
• Irvine, M. M. (July 2001). "Early digital computers at Bell Telephone Laboratories". IEEE Annals of the History of Computing. 23 (3): 25–27. doi:10.1109/85.948904. ISSN 1058-6180. pdf
• Kaisler, Stephen H. (2016). "Chapter Three: Stibitz's Relay Computers". Birthing the Computer: From Relays to Vacuum Tubes. Cambridge Scholars Publishing. pp. 35–37. ISBN 9781443896313.
• "Г. – Bell Labs – Model V" [G. – Bell Labs – Model V]. oplib.ru (in Russian). Archived from the original on September 29, 2022. Retrieved 2017-10-11.

• Alt, Franz L. (1948). "A Bell Telephone Laboratories' computing machine. I". Mathematics of Computation. 3 (21): 1–13. doi:10.1090/S0025-5718-1948-0023118-1. ISSN 0025-5718.
  • Alt, Franz L. (1948). "A Bell Telephone Laboratories' computing machine. II". Mathematics of Computation. 3 (22): 69–84. doi:10.1090/S0025-5718-1948-0025271-2. ISSN 0025-5718.
  • Tomash, Erwin (2008). "The Erwin Tomash Library on the History of Computing: An Annotated and Illustrated Catalog". www.cbi.umn.edu. CBI Hosted Publications. Image: Bell Labs Model V.drawing of Model V, description: A Chapter, pp. 36-37. Retrieved 2018-05-08.
• Andrews, Ernest G. (1949-09-01). "The Bell Computer, Model VI". Proceedings of a Second Symposium on Large-scale Digital Calculating Machinery: 20–31 (58–69).
• "Bell Laboratories Digital Computers". Bell Laboratories Record. www.americanradiohistory.com. XXXV (3): 81–84. Mar 1957.
• Ceruzzi, Paul E. (1983). "4. Number, Please - Computers at Bell Labs". Reckoners: The Prehistory of the Digital Computer, from Relays to the Stored Program Concept, 1935-1945. Greenwood Publishing Group, Incorporated. pp. 95–99. ISBN 9780313233821.
• Bullynck, Maarten (2015). "3. Bell Model V Calculator: Tapes and Controls". Programming men and machines. Changing organisation in the artillery computations at Aberdeen Proving Ground (1916-1946). pp. 9–12.

• "Control Panel, Bell Telephone Laboratories Model 5 Computer". National Museum of American History.