Editing Slide rule (section)

===Decline===
{{See also|History of computing hardware (1960s–present)}}
[[File:TI-30 LED.png|thumb|upright=.7|The TI-30 scientific calculator, introduced for under US$25 in 1976]]
The importance of the slide rule began to diminish as electronic computers, a new but rare resource in the 1950s, became more widely available to technical workers during the 1960s.

The first step away from slide rules was the introduction of relatively inexpensive electronic desktop [[scientific calculator]]s. These included the [[Wang Laboratories]] LOCI-2,<ref>{{cite web|url=https://www.oldcalculatormuseum.com/wangloci.html|title=The Wang LOCI-2|work=oldcalculatormuseum.com}}</ref><ref name="Wang Ad 1966">{{cite journal |last=Wang Laboratories |title=Now you can determine Copolymer Composition in a few minutes at your desk |journal=Analytical Chemistry |volume=38 |issue=13 |pages=62A–63A |date=December 1966 |doi=10.1021/ac50155a005}}</ref> introduced in 1965, which used logarithms for multiplication and division; and the [[Hewlett-Packard]] [[HP 9100A]], introduced in 1968.<ref name="Leibson_2010">{{cite web |title=The HP 9100 Project: An Exothermic Reaction |date=2010 |first=Steven<!-- Steve --> |last=Leibson |url=http://www.hp9825.com/html/the_9100_part_2.html |access-date=2024-06-16}}</ref> Both of these were programmable and provided exponential and logarithmic functions; the HP had [[trigonometric function]]s (sine, cosine, and tangent) and hyperbolic trigonometric functions as well. The HP used the [[CORDIC]] (coordinate rotation digital computer) algorithm,<ref name="Volder_2000">{{cite journal |first=Jack E. |last=Volder |title=The Birth of CORDIC |journal=Journal of VLSI Signal Processing |issn=0922-5773 |volume=25 |issue=2 |pages=101–105 |date=June 2000 |url=http://late-dpedago.urv.cat/site_media/papers/fulltext_2.pdf |archive-url=https://web.archive.org/web/20160304064804/http://late-dpedago.urv.cat/site_media/papers/fulltext_2.pdf |url-status=dead |archive-date=2016-03-04 |access-date=2016-01-02 |doi=10.1023/a:1008110704586 |bibcode=2000JSPSy..25..101V }}</ref> which allows for calculation of trigonometric functions using only shift and add operations. This method facilitated the development of ever smaller scientific calculators.

As with mainframe computing, the availability of these desktop machines did not significantly affect the ubiquitous use of the slide rule, until cheap hand-held scientific electronic calculators became available in the mid-1970s, at which point it rapidly declined. The pocket-sized Hewlett-Packard [[HP-35]] scientific calculator was the first handheld device of its type, but it cost US$395 in 1972. This was justifiable for some engineering professionals, but too expensive for most students.

Around 1974, lower-cost handheld electronic scientific calculators started to make slide rules largely obsolete.<ref>{{cite book |title=Writing and reading across the curriculum |last1=Behrens |first1=Lawrence|last2=Rosen|first2=Leonard J.|year=1982|publisher=[[Little, Brown]]|page=273|quote=Then, just a decade ago, the invention of the pocket calculator made the slide rule obsolete almost overnight...}}</ref><ref>{{cite book |title=e: The Story of a Number |page=16 |last1=Maor |first1=Eli |publisher=Princeton University Press |year=2009 |isbn=978-0-691-14134-3 |quote=Then in the early 1970s the first electronic hand-held calculators appeared on the market, and within ten years the slide rule was obsolete.}}</ref><ref>{{cite book |title=Inventions that Changed the World |last1=Castleden |first1=Rodney |year=2007 |page=157 |publisher=Futura |isbn=978-0-7088-0786-6 |quote=With the invention of the calculator the slide rule became instantly obsolete.}}</ref><ref>{{cite book |title=Beyond calculation: the next fifty years of computing |page=xiv |last1=Denning |first1=Peter J. |author-link1=Peter J. Denning |last2=Metcalfe |first2=Robert M. |author-link2=Bob Metcalfe |isbn=978-0-387-98588-6 |publisher=[[Springer Verlag|Springer]] |year=1998 |quote=The first hand calculator appeared in 1972 and made the slide rule obsolete overnight. |url=https://archive.org/details/beyondcalculatio00pete}}</ref> By 1975, basic four-function electronic calculators could be purchased for less than $50, and by 1976 the [[TI-30]] scientific calculator was sold for less than $25 (${{Formatprice|{{Inflation|US|25|1976|r=2}}|0}} adjusted for inflation).

1980 was the final year of the [[University Interscholastic League]] (UIL) competition in [[Texas]] to use slide rules. The UIL had been originally been organized in 1910 to administer literary events, but had become the governing body of school sports events as well.<ref>{{cite journal |last1=Gabbert |first1=Mike |title=Slide Rule Competition in Texas High Schools |journal=Journal of the Oughtred Society |date=Fall 1999 |volume=8 |issue=2 |pages=56–58 |url=https://osgalleries.org/journal/pdf_files/8.2/V8.2P56.pdf |access-date=5 March 2025}}</ref>