Texas Instruments SR-51 Handheld Electronic Calculator

<< >>
This handheld electronic scientific calculator has a black plastic case with an array of forty small rectangular plastic keys. The white digit keys, decimal point key, and change sign key have only one meaning. The orange total key also has only one meaning. Pushing the gold “2nd” key changes the function of the other keys from what is shown on the key to the “dual function” indicated above it on the keyboard. The device calculated values of a wide range of arithmetic, statistical, logarithmic, trigonometric, hyperbolic trigonometric, and inverse trigonometric functions using the gold, brown, and gray keys. It also has limited memory.
Text above the keys reads: TEXAS INSTRUMENTS SR-51. Behind the keyboard is a switch that may be set at R (radians) or D (degrees). Next to it is an on/off switch. Behind the keyboard is an LED display that shows ten-digit positive and negative numbers and two-digit positive and negative exponents.
The calculator has a jack for a recharger/adapter along the back edge. A sticker on the back gives codes entered to convert from common measures to metric measures. It reads in part: TEXAS INSTRUMENTS (/) super slide rule calculator (/) SR-51. It also gives the serial number SR51 0048134. Above the sticker is a compartment for a battery pack.
Unscrewing three screws on the back reveals the workings of the calculator. It has four chips, two relatively large. One of the large ones is marked: TMC0523NL (/) ΔE7501-5. This is a TMC0523 chip, manufactured in early 1975. The other is marked: TMC0501NL (/) ΔD7503-6. This is a TMC0501 chip, manufactured the same year.
The calculator comes in a black plastic, zippered case with belt loop.
[Advertisement], Boston Globe, February 2, 1975, p. 54. Texas Instruments “super slide-rule calculator” selling for $224.95.
[Advertisement], Los Angeles Times, February 22, 1975, p. E4. Give price of $225.
[Advertisement], Washington Post, March 11, 1975, p. A4. Give price of $199.95.
Guy Ball and Bruce Flamm, The Complete Collector’s Guide to Pocket Calculators, Tustin, CA: Wilson/Barnett, 1997, p. 154. They date the SR-51 calculator to about 1975.
Currently not on view
date made
Texas Instruments
Physical Description
metal (circuitry; zipper material)
paper (sticker material)
plastic (case; keys; carrying case material)
overall: 1 1/4 in x 3 in x 5 3/4 in; 3.175 cm x 7.62 cm x 14.605 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


Add a comment about this object