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Logic Unit for the Green Machine, A Prototype Desktop Electronic Calculator

Logic Unit for the Green Machine, A Prototype Desktop Electronic Calculator

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As a graduate student in electrical engineering at the University of California – Berkeley, Thomas E. Osborne began thinking about the design of a desktop electronic calculator that could compute the very large and very small numbers encountered in scientific work. In January of 1964 he formed the firm Logic Design, Inc., to develop his ideas. By late 1964 he had built a prototype keyboard and display (1978.0311.01), as well as this prototype logic unit.
The framework of the logic unit is a group of five rectangular perforated boards, arranged in the shape of a box. Numerous smaller boards are perpendicular to the base and to three of the sides. Metal supports are along the base of two opposite sides. Circuit components include transistors, resistors, capacitors, diodes, and a plug. A second plug is loose in the box.
Elements of the green machine were incorporated in Hewlett-Packard’s first commercial electronic calculator, the HP9100. For a prototype of that machine, see 1978.0311.03. For related documentation, see invention notebooks and photographs by Osborne (1978.0311.03 through 1978.0311.14). For purchase orders of components used in the prototype, see 1985.0264.01.
Bernard M. Oliver, “How the Model 9100A Was Developed,” Hewlett-Packard Journal, September, 1968. A copy of this article is at the HP Museum website.
The website of the University of Wyoming contains biographical information about Osborne.
Currently not on view
Object Name
electronic calculator prototype
date made
date received
Osborne, Thomas E.
place made
United States: California, Berkeley
Physical Description
plastic (boards, wiring material)
metal (endpieces, wires material)
rubber (plug material)
glass (components material)
overall: 19 cm x 42 cm x 27 cm; 7 15/32 in x 16 17/32 in x 10 5/8 in
ID Number
accession number
catalog number
Credit Line
Gift of Hewlett-Packard Company
See more items in
Medicine and Science: Computers
Desktop Electronic Calculators
Computers & Business Machines
Data Source
National Museum of American History
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