Texas SR-50A

The Texas Instruments SR-50 is an easy-to-operate scientific calculator with trigonometric and hyperbolic functions, the logarithms and their inverses. It had 40 keys, and flat sliding switches for degrees/radians and on/off. "SR" stood for "slide rule."
Size: 147 x 81 x 32 mm3
Introduced in 1974 at the price of $175 or DM520.


  • Algebraic entry
  • Accuracy to 13 digits
  • Floating decimal point or scientific notation
  • Fully portable


The SR-50A Slide Rule Colculator is designed for use by scientists, engineers, and students who require accuracy and reliability in a portable scientific calculator. The SR-50A is a powerful computational tool capable of processing a wide range of problems from simple arithmetic to complex scientific calculations. The SR-50 has been designed with state-of-the-art MOS solid state circuitry, constructed with high-quality components throughout, and assembled With precise workmanship.

Algebraic Entry - The SR-50 uses the algebraic entry method to simplify data entry into the calculator. For simple problems, the numbers and algebraic functions are entered into the calculator in the same sequence as they are stated algebraically.

SR-50 & Battery Charger

SR-50 & Battery Charger
Credit to Tullio

Serial Number

SR-50A Serial Number


The calculator has been completely disassembled; the keys were washed with a neutral pH detergent and then reassembled; the contact springs of the batteries, corroded over time, have been replaced; the cells of the battery pack have been replaced with new ones of higher capacity.

The old batteries

SR-50 Battery Pack


The new batteries

SR-50 Battery Pack


The final result


See our page on the internal accuracy of the calculators

Visit our page on the internal accuracy of calculators