Texas Instruments SR-56 Handheld Electronic Calculator

Texas Instruments SR-56 Handheld Electronic Calculator

<< >>
Usage conditions apply
This scientific calculator is a modification of the Texas Instruments SR-50A and a less expensive device than the contemporary SR-52. A handheld electronic calculator, it has a black plastic case with an array of forty small rectangular plastic keys. In addition to ten digit keys, a decimal point key, a change sign key, a total key, four arithmetic function keys, a clear entry key, and clear key, the calculator has twenty-one further keys. Many keys (including some of the number keys) take on a second function if the "2nd" key is pushed. This second function is indicated on the keyboard above the key. Texas Instruments advertised this as a programmable calculator.
Text above the keys reads: TEXAS INSTRUMENTS SR-56. 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 instructions. It reads in part: TEXAS INSTRUMENTS (/) SR-56. It also gives the serial number SR-56 2400279. It also reads: Assembled in USA. Above the sticker is a battery compartment. A mark below the sticker reads: LTA1677.
Unscrewing three screws on the back reveals the workings of the calculator. It has six chips, three relatively large. One of the large ones is marked: TMC0538NL (/) P 7650. This is a TMC0538 chip, manufactured in 1976. Another is marked: TMC0501NL (/) EP 7706. This is a TMC0501 chip, manufactured in 1977. The third is marked: TMC0537NL (/) AP 7644.
The calculator comes in a black plastic, cloth-lined, zippered case with loop.
[Advertisement], Boston Globe, February 4, 1976, p. 31. New, programmable SR-56 advertised as selling for $179.95.
[Advertisement], Los Angeles Times, February 28, 1976, p. OC_A5. New programmable SR-56 selling for $179.95. Compatible with PC-100 printer.
[Advertisement], Washington Post, April 23, 1976, p. B4. Calculator has list price of $179.95, sale price of $159.95. Also lists SR-52, with program strips, selling for $359.95.
[Advertisement], Los Angeles Times, July 10, 1976, p. C5. Lists SR-56 as having list price of $179.95, sale price of $89.95.
[Advertisement], Los Angeles Times, October 9, 1976, p. C7. Lists SR-56 as selling for $89.95, regular price $109.95.
[Advertisement], Los Angeles Times, December 22, 1976, p. D8. Price for SR-56 $85.
[Advertisement], Los Angeles Times, May 28, 1977, p. C4. Price for SR-56 $79.
Currently not on view
Object Name
electronic calculator
date made
Texas Instruments
Physical Description
plastic (case; keys; carrying case material)
metal (circuitry; zipper 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
Nominate this object for photography.   

Our collection database is a work in progress. We may update this record based on further research and review. Learn more about our approach to sharing our collection online.

If you would like to know how you can use content on this page, see the Smithsonian's Terms of Use. If you need to request an image for publication or other use, please visit Rights and Reproductions.


I own a SR-56 calculator that is in excellent condition (complete with Manuals, Charger, and Case). Although the Battery Pack is still intact, I am concerned that it might someday corrode. What do you suggest that I do to preserve the product and battery pack? Thank you.
Behind the keyboard is a switch that may be set at R (radians) or D (degrees). The key should read G (gradians) or D (degrees). Wikipedia The gradian is a unit of measurement of an angle, equivalent to 1/400 of a turn, 9/10 of a degree, or π/200 of a radian. The gradian is defined as 1/100 of the right angle (in other words, there are 100 gradians in the right angle), which implies a full turn being 400 gradians. To change it radians, you press 2nd RAD.

Add a comment about this object