Keystone SC 656 Handheld Electronic Calculator

After achieving some success selling four-function calculators, the Keystone Division of Berkey Photo, Inc., began to manufacture calculators with more extensive capabilities. This handheld electronic calculator has a plastic case and trim, a metal keyboard painted black, and thirty plastic keys with a square base and circular tops. The four lower rows of keys include ten digit keys, a decimal point key, a key for the number pi, four arithmetic function keys, a total key, a cancel key, a change sign key, and a memory key. Two rows of function keys above this are for trigonometric and inverse trigonometric functions, exchange, exponents, natural logarithms, powers, logarithms to the base 10, and square roots. Above this is a charging indicator light, a radian/degree switch, and an on/off switch. The socket for a power jack is on the right side near the top.

A mark above the keyboard reads: Keystone SC 656. Behind this is a nine-digit vacuum fluorescent display. Behind this, attached to the back edge, is a holder for a loop that makes it possible to suspend the calculator. The loop itself is missing. A mark on the front edge reads: Made in U S A.

A sticker on the back gives instructions. Text at the bottom reads: Berkey (/) 2 Keystone Place (/) Paramus, New Jersey 07652 Serial # C251556.

Compare 1986.0988.365.

Berkey Keystone began selling calculators in 1972, and was out of the business by 1977. This calculator appears to be a relatively late example, hence the rough date.

Reference:

Victor K. McElheny, “Berkey – A Photo Finish in a Race with Giants,” New York Times, April 17, 1977, p. F1.

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