Texas Instruments Exactra 20 Handheld Electronic Calculator (TI-20)

Texas Instruments Exactra 20 Handheld Electronic Calculator (TI-20)

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This handheld electronic calculator is one of a series of “exactra” calculators introduced by Texas Instruments in the spring of 1974. It has an off-white plastic case, an orange keyboard, and eighteen nearly square plastic keys. These include ten digit keys, a clear entry key, a clear key, a decimal point key, four arithmetic function keys, and a constant key. An on/off switch and a $/F (for dollars / floating point) key are on the left in the top row of keys. A mark at the top of the keyboard reads: exactra 20. Behind this is a six-digit red LED display.
The calculator has no provision for a charger/adapter. A battery compartment at the top of the back would hold three AA alkaline or carbon-zinc batteries. A mark molded into the plastic on the back reads in part: TI-20 ELECTRONIC CALCULATOR (/) MADE BY TEXAS INSTRUMENTS INCORPORATED. It also gives instructions. Toward the bottom of the back is the stamp: 274. A tag below this reads: SERIAL NUMBER 2000036485.
Unscrewing two screws on the back allow one to remove it. The calculator has two chips. The larger one is marked: TMS 0135 NC (/) C7422. This is a TMS0135 chip. The smaller one is marked: M7419 (/) SN27882.
[Advertisement], New York Times, May 2, 1974, p. 18. Exactra 20 selling for $39.99.
[Advertisement], Chicago Tribune, Dec 15, 1974, p. T17. Texas Instruments Exactra 20 selling for $19.88.
[Advertisement], New York Times, September 10, 1975, p. 6. Exactra 20 calculator, regularly $29.99, now $14.99.
Online Datamath Museum, accessed June 2, 2015.
Currently not on view
Object Name
electronic calculator
date made
Texas Instruments
Physical Description
plastic (overall material)
metal (circuitry material)
paper (sticker material)
overall: 1 3/8 in x 2 5/8 in x 5 in; 3.4925 cm x 6.6675 cm x 12.7 cm
ID Number
catalog number
accession number
Credit Line
Gift of John B. Priser
See more items in
Medicine and Science: Computers
Handheld Electronic Calculators
Computers & Business Machines
Data Source
National Museum of American History
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