Texas Instruments TI-2550 III Handheld Electronic Calculator


In 1972 Texas Instruments began selling electronic calculators under its own name. The first of these was the Datamath or TI-2500. Over the next few years, TI sold modifications of the TI-2500 that had different forms of battery (such as the TI-2500B, the TI-2500II, the TI-2510, and the TI-2550III), a different color case (the TI-2510 and the TI-2550III), a key for taking percentages (the TI-2550, the TI-2550II, and the TI-2550III), and keys for additional functions (the TI-2550, the TI-2550II and the TI-2550III). This is an example of the TI-2550III.

The calculator has an array of thirty-five rectangular plastic keys. These include ten digit keys, four arithmetic function keys, a clear key, a clear entry key, a decimal point key, and a total key. Also included are a change sign key, a percentage key, four memory keys, an inverse key, a square key, a square root key, and a reverse entry (RV) key. The RV key replaced an entry in the display with the immediately preceding entry.

The on/off switch is above the keyboard on the right. A mark above it reads: TEXAS INSTRUMENTS TI-2550III. Behind this is an eight-digit blue vacuum fluorescent display.

There is a jack for a power adapter along the back edge (according to instructions for the calculator found online, this would have part number AC9310A). The back has a battery compartment that would hold a rechargeable battery pack (according to instructions for the calculator, this would have model number BP-3).

A sticker on the back of the calculator reads in part: US PAT 3819921 OTHER PATENTS PENDING (/) TEXAS INSTRUMENTS (/) TI-2550-III (/) electronic Calculator (/) Serial No. (/) 2550-III 075877. It also reads in part: ASSEMBLED IN USA. A mark below the label reads: 4576LTA.

Unscrewing four screws from the back of the calculator reveals the circuit board. The largest chip is marked: TMS1043NL (/) KBSΔ7642.

The calculator has a black plastic zippered case.


[Advertisement], Boston Globe, November 25, 1976, p. 92. Selling for $29.95.

[Advertisement], Los Angeles Times, January 29, 1977, p. C5. Advertised as selling for $28.95.

Guy Ball and Bruce Flamm, The Complete Collector’s Guide to Pocket Calculators, Tustin, CA: Wilson/Barnett, 1997, p. 158. They give a 1976 price of $34.95.

Online Datamath Museum.

Date Made: 1976

Maker: Texas Instruments

Location: Currently not on view

See more items in: Medicine and Science: Computers, Computers & Business Machines, Handheld Electronic Calculators


Exhibition Location:

Credit Line: Gift of John B. Priser

Data Source: National Museum of American History

Id Number: 1986.0988.347Catalog Number: 1986.0988.347Accession Number: 1986.0988

Object Name: electronic calculator

Physical Description: plastic (case; keys; carrying case material)metal (circuitry; zipper material)paper (sticker material)Measurements: overall: 1 1/4 in x 3 in x 5 3/4 in; 3.175 cm x 7.62 cm x 14.605 cm

Guid: http://n2t.net/ark:/65665/ng49ca746ac-f032-704b-e053-15f76fa0b4fa

Record Id: nmah_1364041

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