Summit SI-90 Handheld Electronic Calculator

Summit SI-90 Handheld Electronic Calculator

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This is the most advanced of the Summit scientific handheld calculators in the Smithsonian collections. It has a dark brown and tan plastic case and an array of thirty-six rectangular plastic keys. The lower four rows of keys include ten digit keys, a decimal point key, a pi key, a total key, a memory key, a clear entry key, a clear key, and four arithmetic function keys. Above this are keys for a wide variety of functions, including shifting from degrees to radians, logarithms to the base ten, natural logarithms, exponents, trigonometric and inverse trigonometric functions, reciprocals, square roots, powers, parentheses, switching the content of registers, and change sign. Behind the keyboard is a ten-digit display with further lights for sign and two-digit exponent. A jack for a power adapter is at the back. A tag on the front reads: Summit.
A tag on the back of the calculator reads: THE SCIENTIFIC. It also reads: MODEL SI-90 (/) SERIAL NO. 51832 (/) Tm SUMMIT INTERNATIONAL CORP> (/) SALT LAKE CITY, UTAH.
The calculator has a black leather zippered, cloth-lined case. It also has a black AC adapter-charger. Both of these are marked: Summit. The instrument is in a foam case that fits in a cardboard box. The price on one tag on the box is $149.95, marked down to $69.95, marked down to $31.99. The price on another tag is $109.95, marked down to $31.98.
[Advertisement], The Daily Herald (Provo, Utah), September 24, 1975, p. 15. Close-out sale on Summit calculators, including SI-90. List price of that model is $99, on sale for $49.
[Advertisement], Desert News, March 3, 1976, p. 20A. Factory closeout sale on the Summit SI90 lists a price of $49.
Guy Ball and Bruce Flamm, The Complete Collector’s Guide to Pocket Calculators, Tustin, CA: Wilson/Barnett, 1997, p. 149.
Summit International Corporation, Professional calculator for the scientist, engineer and mathematician: Instruction Manual for: SUMMIT SI90, Salt Lake City, Utah: Summit International, no date. This manual is online at, accessed November 21, 2014. Summit International is listed here as a subsidy of Trans Atlas Corporation.
Currently not on view
Object Name
electronic calculator
date made
ca 1974
Summit International Corporation
place made
United States: Utah, Salt Lake City
Physical Description
plastic (case; power supply; keys; display cover; foam material)
metal (circuitry material)
paper (stickers; box material)
overall: 1 1/2 in x 3 in x 6 in; 3.81 cm x 7.62 cm x 15.24 cm
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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