Texas Instruments SR-50 Handheld Electronic Calculator

This is an example of a scientific calculator introduced by Texas Instruments in 1974 that had more extensive capabilities than any previous TI calculator. The handheld electronic calculator has a black plastic case with an array of forty small rectangular plastic keys. In addition to ten digit keys, a decimal point key, a change sign key, a total key, four arithmetic function keys, a clear entry key, and a clear key; the calculator has twenty-one further keys. Some are for entering exponents, pi, storage, recall, summation, exchange, powers, squares, square roots, reciprocals, factorials, general roots, hyperbolic functions, conversion between radians and degrees, natural logarithms, exponents, and common logarithms. Four keys are for trigonometric functions and inverse trigonometric functions. This was the first Texas Instruments calculator to include trigonometric and hyperbolic functions.

Text above the keys reads: TEXAS INSTRUMENTS SR-50. Behind the keyboard is a switch that may be set at R (radians) or D (degrees). Next to it is an on/off switch. Behind the keyboard is an LED display that shows ten-digit positive and negative numbers and two-digit positive and negative exponents.

The calculator has a jack for a recharger/adapter along the back edge. A sticker on the back gives instructions. It also gives the serial number SR-50 0523906. It also reads: MANUFACTURED BY (/) TEXAS INSTRUMENTS (/) INCORPORATED (/) DALLAS TEXAS. It also reads: [copyright] 1973 USA. Above the sticker is a compartment for three batteries. A mark below the sticker reads: LTA4375.

Unscrewing three screws on the back reveals the workings of the calculator. It has two chips of roughly equal size. One is marked: TMC0521NL (/) ΔE7441-5. This is a TMC0521 chip, manufactured in late 1974. The other is marked: TMC0501NL (/) D7441-5. This is a TMC0501 chip, manufactured at the same time.

The calculator comes in a black plastic zippered case with a belt loop

References:

[Advertisement], Los Angeles Times, February 22, 1975, p. E4. Gives price of $149.95 reduced to $119.00.

[Advertisement], Washington Post, March 11, 1975, p. A4. Gives price of $117.95.

Guy Ball and Bruce Flamm, The Complete Collector’s Guide to Pocket Calculators, Tustin, CA: Wilson/Barnett, 1997, p. 154. They give a 1974 price of $170.

Online Datamath Museum, accessed May 15, 2015.

Currently not on view