Texas Instruments TI-2500B (Datamath) Handheld Electronic Calculator

Texas Instruments TI-2500B (Datamath) Handheld Electronic Calculator

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This is an example of an early handheld electronic calculator marketed by Texas Instruments under its own name. The 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: Datamath. 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.
The back of the calculator has a compartment for storing either three rechargeable nickel-cadmium batteries or four AA sized non-rechargeable batteries. According to Flamm, it is the presence of this compartment that distinguishes the TI-2500 from the TI-2500B.
A sticker on the compartment cover reads: TI-2500B electronic calculator. It also reads in part: Datamath (/) electronic calculator (/) A Product of Texas Instruments Incorporated. It also reads in part: Serial Number (/) 2500B 564926. The sticker indicates that the calculator had a built-in battery that gave four to six hours of portable operation and could be fully recharged in ten hours using an AC9130 adapter/charger.
Unscrewing three long screws on the back of the case does not reveal the chips.
This modification of the TI-2500 was introduced in 1974 and discontinued the same year.
Compare 1986.0988.188, 1986.0988.189, 1986.0988.190, 1986.0988.342, and 1986.0988.359.
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 13, 2015.
Currently not on view
Object Name
electronic calculator
Other Terms
electronic calculator; Handheld
date made
Texas Instruments
Physical Description
plastic (case; keys; feet; circuit board material)
metal (circuitry material)
paper (sticker material)
overall: 1/2 in x 2 3/4 in x 5 1/2 in; 1.27 cm x 6.985 cm x 13.97 cm
ID Number
accession number
catalog number
Credit Line
Gift of John B. Priser
See more items in
Medicine and Science: Computers
Computers & Business Machines
Handheld Electronic Calculators
Data Source
National Museum of American History
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I was the engineer that designed the Datamath2500B. I received a patent on the switching that allowed 4 NiCad or 3 alkaline batteries. (never was used). I also built the only prototype for the LCD version. TI had produced a chip for the LCD version. It took me 2 month to kill the project because the chip had a DC component that turned the LCDs they had black in about 10 minutes.

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