Slide Rule Calculator Views
The wonderful electronic slide rule SR-50 marked a milestone in the history of calculators manufactured by Texas Instruments. It added trigonometric and hyperbolic functions, the logarithms and their inverses to the scientific functions of the SR-10, SR-11 and SR-16 line of calculators. The calculator was placed with big success against Hewlett-Packard's HP-35 and produced in high quantity. The internal construction was very rigid compared with other models. To reduce manufacturing costs and to give a similar appearence to the SR-52 and SR-56 calculators the SR-50 was replaced within 18 month with the SR-50A. Don't miss the rare SR-51.
William Oughtred and others developed the slide rule in the 17th century based on the emerging work on logarithms by John Napier. Before the advent of the pocket calculator, it was the most commonly used calculation tool in science and engineering. The use of slide rules continued to grow through the 1950s and 1960s even as digital computing devices were being gradually introduced; but around 1974 the electronic scientific calculator made it largely obsolete[2][3][4][5] and most suppliers left the business.
One slide rule remaining in daily use around the world is the E6B. This is a circular slide rule first created in the 1930s for aircraft pilots to help with dead reckoning. With the aid of scales printed on the frame it also helps with such miscellaneous tasks as converting time, distance, speed, and temperature values, compass errors, and calculating fuel use. The so-called prayer wheel is still available in flight shops, and remains widely used. While GPS has reduced the use of dead reckoning for aerial navigation, and handheld calculators have taken over many of its functions, the E6B remains widely used as a primary or backup device and the majority of flight schools demand that their students have some degree of proficiency in its use.
Another step toward the replacement of slide rules with electronics was the development of electronic calculators for scientific and engineering use. The first included the Wang Laboratories LOCI-2,[17][18] introduced in 1965, which used logarithms for multiplication and division and the Hewlett-Packard HP-9100, introduced in 1968.[19] The HP-9100 had trigonometric functions (sin, cos, tan) in addition to exponentials and logarithms. It used the CORDIC (coordinate rotation digital computer) algorithm,[20] which allows for calculation of trigonometric functions using only shift and add operations. This method facilitated the development of ever smaller scientific calculators.
Slide Rule Calculator Images
