History and Curiosity

Slide Rule Decline 

Texas Instruments (TI) invented the first integrated circuit in 1958, courtesy of TI inventor Jack Kilby, and the handheld calculator, a prototype called the "Cal Tech," invented by TI's Jerry Merryman in 1967. However, the first handheld scientific calculator or "slide rule" offered to the public was Hewlett-Packard's. The HP-35 was named by Bill Hewlett for the number of keys on the calculator, and in 1972, the year the slide rule as we know it began to decline, Hewlett-Packard announced the HP-35 as a fast, highly accurate electronic slide rule with solid-state memory similar to a computer. Even though they had a launch price of $395.00, engineers and engineering students flocked to stores to buy them (much like the iPod craze today). Some students even sold their cars to afford one. However, because the exorbitant cost of producing HP calculators made them unaffordable to 90% of the general population, the slide rule remained popular and useful for another four years. According to the ISRM, the official death date of the slide rule was June 13, 1976, when Texas Instruments introduced the TI-30 single-chip slide rule scientific calculator for $24.95, which was below the cost of a comparable slide rule. There was no longer any cost advantage for new students, technicians, and engineers to purchase a slide rule, since everyone could afford the TI-30. Coincidentally, just one month later, on July 11, 1976, Kueffel & Esser, the oldest and largest slide rule manufacturer in the United States, produced its last slide rule. In the following month of August 1976, Pickett Industries followed suit, discontinuing all production of its slide rules.