JC Penney MM3R Handheld Electronic Calculator

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This four-function calculator has a tan plastic case, an array of ten oval digit keys, and a decimal point key. It also has four blue arithmetic function keys to the right of these and has clear entry and clear keys to the left. A constant switch is above the clear keys. The on/off switch is on the right above the keyboard. A mark to the left of it reads: JCPenney. The eight-digit LED display is at the back. The back edge has a socket for a power adapter.
A sticker on the back reads: JCPenney (/) Electronic Calculator (/) VOLTAGE 6V CURRENT 0.2A (/) MODEL MM3R SERIAL No. 126131 (/) Made in U.S. A.
This model is similar to the Commodore MM3R and probably was made by Commodore.
J. C. Penney is a chain of American department stores.
Guy Ball and Bruce Flamm, The Complete Collector’s Guide to Pocket Calculators, Tustin, CA: Wilson/Barnett, 1997, pp. 81–82.
Currently not on view
date made
ca 1975
J.C. Penney Company
place made
United States
Physical Description
plastic (case; display cover; keys material)
gallium arsenide (display chips material)
metal (circuitry material)
paper (sticker material)
overall: 2.5 cm x 7.4 cm x 10 cm; 31/32 in x 2 29/32 in x 3 15/16 in
ID Number
catalog number
accession number
Credit Line
Gift of John B. Priser
See more items in
Medicine and Science: Computers
Handheld Electronic Calculators
Computers & Business Machines
Data Source
National Museum of American History


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