This is a version of the Datamath calculator (the TI-2500) produced by Texas Instruments for sale by Longines Symphonette. Longines Symphonette was a subsidiary of the Longines-Wittnauer Watch Company that began sponsoring radio concerts on three large American networks in the 1940s. In about 1960 they began selling tapes, records, radios, and recording equipment as well as watches. By 1970 sales in watches had dwindled to less than half of total sales. Longines also worked with Texas Instruments on the development of digital watches.
The handheld electronic calculator has a tan plastic case with a dark brown keyboard. It has an array of eighteen keys, sixteen of them square and two rectangular. These include ten digit keys, a decimal point key, a total key, four arithmetic function keys, a clear entry key, and a clear key. A switch at the right in the top row of keys may be set at “CHAIN” or “CONST.” A mark above this switch reads: Longines Symphonette. Behind the keyboard is an eight-digit LED display.
A jack for a power outlet is along the back edge. An on/off switch is on the left side. A sticker on the back reads: Longines Symphonette (/) electronic calculator (/) A Product of Texas Instruments Incorporated. It also reads in part: Serial Number (/) D1000 37880. The sticker indicates that the calculator had a built-in battery that gave four to six hours of portable operation and fully recharged in ten hours. There is no easy access to the batteries.
Unscrewing three long screws on the back of the case allows one to remove the back. The inside has five chips. The largest reads: TMS0119NC (/) 7325. This is a TMS0119 chip, manufactured in the 25th week of 1973. A mark on the circuit board reads: CAL30367H (/) MADE IN U.S.A. There is space for four soldered batteries.
The instrument has a black plastic zippered carrying case.
This appears to be the same design as the second version of the TI-2500, introduced in February 1973 (see especially 1986.0988.188 as well as 1986.0988.189, 1986.0988.190, and 1986.0988.342).
References:
Guy Ball and Bruce Flamm, The Complete Collector’s Guide to Pocket Calculators, Tustin, CA: Wilson/Barnett, 1997, p. 157.
Online Datamath Museum, accessed May 15, 2015.
Isadore Barmash, “Longines Is Ticking With Taped Tunes,” New York Times, September 8, 1970, p. 59, 62.
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