overall: 1 1/2 in x 3 in x 6 1/4 in; 3.81 cm x 7.62 cm x 15.875 cm
United States: Texas, Dallas
This is an example of the first model of a scientific calculator marketed by Texas Instruments. The handheld electronic calculator has a black and ivory-colored plastic case with an array of twenty-three plastic keys. Twenty-one of these are square, the 0 and the total keys are rectangular. In addition to ten digit keys, a decimal point key, a total key, and four arithmetic function keys, the calculator has a reciprocal key, a square key, a square root key, a change sign key, an enter exponent key, a clear key, and a clear display key. Text above the keyboard, just below the display and to the left, reads: SR10. Behind the keyboard is a 12-digit LED display. Numbers larger than eight digits are displayed in scientific notation. A mark behind the display reads: TEXAS INSTRUMENTS. An on/off switch is right and slightly above this.
The back edge of the calculator has a jack for a recharger/adapter. A sticker on the back gives extensive instructions. It also gives the serial number SR10 275812.
Unscrewing screws near the top and bottom of the back reveals the workings of the calculator. It has a total of five chips. The largest of these is marked TMS 0120 NC (/) C7333. This is a TMS0120 chip, manufactured in mid-1973. Also in the case is space for three AA nickel-cadmium batteries.
The leather zippered case has both a loop and a hook for attaching the calculator to a belt. It also holds an instruction pamphlet entitled Texas Instruments electronic slide rule calculator SR-10, copyrighted 1973. A warranty registration on the inside of the back page indicates these instructions were originally sold with an SR-10 calculator with serial number 170334, purchased on September 27, 1973.
Texas Instruments described the SR-10 as an “electronic slide rule calculator,” hence the “SR” in the name. The first version of the device, introduced in 1972, did not have the mark SR-10 on the keyboard. The second version (introduced 1973) and the third (introduced 1975) did. This is an example of the first version. According to Ball & Flamm, it initially sold for $149.95.
Compare 1986.0988.351, 1986.0988.354, and 1986.0988.356.
Guy Ball and Bruce Flamm, The Complete Collector’s Guide to Pocket Calculators, Tustin, CA: Wilson/Barnett, 1997, p. 153.
The online Datamath Museum includes versions of the SR-10 from 1972, 1973, and 1975.