Electromechanical Computer Component, Bell Telephone Laboratories Model 5, Calculator 401 and Calculator 402
date: label: Date made
content: 1947
name: label: maker
content: Bell Telephone Laboratories
notes: label: Description
content: These are Calculator 401 and Calculator 402 for the Bell Telephone Laboratories Model V electromechanical computer. They are in one frame. Most circuitry in these two units is covered by metal doors. Calculator 401 has five rows of capacitors at the top; calculator 402 six rows.
label: Description
content: These parts are part of a very large programmable calculator built by Bell Telephone Laboratories of New York for the U.S. Army. By the mid-twentieth century, improving communications required complicated calculations. In order to improve the clarity and range of long distance voice signals, George Stibitz, a research mathematician at Bell Labs, needed to do calculations using complex numbers. Stibitz and Bell Labs engineer Sam Williams completed a machine for this purpose in 1939–it later was called the Bell Labs Model I. With the outbreak of World War II, Stibitz and Bell Labs turned their attention to calculations related to the aiming and firing of antiaircraft guns. Stibitz proposed a new series of relay calculators that could be programmed by paper tape to do more than one kind of calculation. The BTL Model 5 was the result. The machine consisted of twenty-seven standard telephone relay racks and assorted other equipment. It had over 9000 relays, a memory capacity of thirty seven-digit decimal numbers, and took about a second to multiply two numbers together. Two copies of the machine were built. This one was used by the U.S. Army for ballistics work at Aberdeen, Maryland and then at Fort Bliss, Texas. Machines that used relays were reliable, but slower than those using vacuum tubes, and soon gave way to electronic computers.
label: Location
content: Currently not on view
place: label: place made
content: United States: New Jersey, New Providence, Murray Hill
topic: label: Subject
content: Mathematics
setName: label: See more items in
content: Medicine and Science: Mathematics
label: See more items in
content: Computers & Business Machines
creditLine: label: Credit Line
content: Gift of Bell Telephone Laboratories
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: 1987.0821.03
label: accession number
content: 1987.0821
label: catalog number
content: 1987.0821.03
objectType: label: Object Name
content: electromechanical computer componente
label: Object Name
content: electromechanical computer component
physicalDescription: label: Measurements
content: overall: 244 cm x 150 cm x 25 cm; 96 1/16 in x 59 1/16 in x 9 27/32 in