Summit SI-90 Handheld Electronic Calculator

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.

References:

[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 wass.net, accessed November 21, 2014. Summit International is listed here as a subsidy of Trans Atlas Corporation.

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