Unicom 202SR Handheld Electronic Calculator

The calculator manufacturer Unicom was started by integrated circuit manufacturer American Microsystems, Inc., and purchased by Rockwell International in 1972. Rockwell would soon begin to sell calculators under its own name.
This handheld electronic calculator is designed for scientific as well as arithmetic calculations. It has a tan plastic case and an array of twenty sloping square plastic keys. Symbols on the keys are for ten digits, a decimal point, four arithmetic functions, total, change sign, transfer, and clear. A twentieth key is marked F. Pushing it changes the meaning of the other keys to a function denoted above the key. The keys will then allow one to evaluate logarithms, exponents, powers, trigonometric functions, inverses, pi, and inverse trigonometric functions. Five keys serve various memory functions.
The on/off switch is above the keyboard on the left. A switch on the right above the keyboard allows for entries of angles in degrees or radians.
Behind the keyboard is an eight-digit vacuum fluorescent display. A jack for a battery charger is along the back edge.
A compartment at the bottom of the back of the calculator holds four AA batteries. A sticker above it reads: 202 SLIDE RULE (/) Rechargeable NI-Cad Batteries. Use Unicom NI-Cad bat- (/) tery charger to recharge. Allow 7 hours for full charge. (/) Do NOT use battery charger with NI-CAD batteries re- (/) moved. Disposable Batteries: Use 4 AA alkaline batteries. Do NOT use battery charger with disposable batteries. (/) Unicom Systems (/) Rockwell International 192609-50 (/) UNICOM SYSTEMS, SUNNYDALE, CALIFORNIA 94086 (/) ASSEMBLED IN MEXICO.
The calculator has a brown carrying case that has been cut so that it might be worn on a belt.
[Advertisement], Los Angeles Times, November 13, 1973, p. C6. Scientific calculator for under $200 – cost $195.00.
[Advertisement], Chicago Tribune, September 10, 1974, p. A9. Calculator advertised as on sale for $119.88.
[Advertisement], Chicago Tribune, March 11, 1975, p. 6. Calculator advertised as having regular price of $109.95, sale price of $79.88.
Guy Ball and Bruce Flamm, The Complete Collector’s Guide to Pocket Calculators, Tustin, CA: Wilson/Barnett, 1997, pp. 165–166.
Currently not on view
Object Name
electronic calculator
date made
Rockwell International
Physical Description
plastic (case; keys; display cover; carrying pouch material)
metal (circuitry material)
paper (sticker material)
overall: 1 1/2 in x 3 1/4 in x 6 1/8 in; 3.81 cm x 8.255 cm x 15.5575 cm
place made
ID Number
catalog number
accession number
See more items in
Medicine and Science: Computers
Handheld Electronic Calculators
Computers & Business Machines
Data Source
National Museum of American History, Kenneth E. Behring Center


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