Editing Reverse Polish notation (section)

==== Early history ====
The first computer implementing a form of reverse Polish notation (but without the name and also without a [[stack machine|stack]]), was [[Konrad Zuse]]'s [[Z3 (computer)|Z3]], which he started to construct in 1938 and demonstrated publicly on 12 May 1941.<ref name="parTU_2000"/><ref name="Zuse_2008"/><ref name="DHM_2013"/><ref name="Bundesmann_2016"/> In dialog mode, it allowed operators to enter two operands followed by the desired operation.{{refn|group=z3|In reference to "In dialog mode, it allowed operators to enter two operands followed by the desired operation" for the Z3 computer, the following citations are relevant :<ref name="Ceruzzi_1980"/><ref name="Ceruzzi_1983"/><ref name="Rojas_1997"/><ref name="Zuse_2005"/><ref name="Zuse_2008"/><ref name="Bonten_2009"/><ref name="Bundesmann_2016"/><ref name="WDF_2018"/><ref name="Tremmel_2021"/>}} It was destroyed on 21 December 1943 in a bombing raid.<ref name="Zuse_2008"/> With Zuse's help a first replica was built in 1961.<ref name="Zuse_2008"/> The 1945 [[Z4 (computer)|Z4]] also added a 2-level [[stack machine|stack]].<ref name="Blaauw-Brooks_1997"/><ref name="LaForest_2007"/>

Other early computers to implement architectures enabling reverse Polish notation were the [[English Electric Company]]'s [[English Electric KDF9|KDF9]] machine, which was announced in 1960 and commercially available in 1963,<ref name="Beard_1997"/> and the [[Burroughs B5000]], announced in 1961 and also delivered in 1963:

Presumably, the KDF9 designers drew ideas from Hamblin's [[GEORGE (autocode system)|GEORGE]] (General Order Generator),<ref name="Hamblin_1957_1"/><ref name="Hamblin_1957_2"/><ref name="Hamblin_1958"/><ref name="Duncan_1977"/><ref name="Allen_1985"/><ref name="LaForest_2007"/> an [[autocode]] programming system written for a [[English Electric DEUCE|DEUCE]] computer installed at the [[University of Sydney]], Australia, in 1957.<ref name="Hamblin_1957_1"/><ref name="Hamblin_1957_2"/><ref name="Hamblin_1958"/><ref name="Beard_1997"/>

One of the designers of the B5000, [[Robert S. Barton]], later wrote that he developed reverse Polish notation independently of Hamblin sometime in 1958 after reading a 1954 textbook on symbolic logic by [[Irving Copi]],<ref name="NewApproach"/><ref name="B5000_1985"/><ref name="Galler-Rosin_1985"/> where he found a reference to Polish notation,<ref name="Galler-Rosin_1985"/> which made him read the works of Jan Łukasiewicz as well,<ref name="Galler-Rosin_1985"/> and before he was aware of Hamblin's work.

[[Friden, Inc.|Friden]] introduced reverse Polish notation to the desktop calculator market with the [[Friden EC-130|EC-130]], designed by [[Bob Ragen|Robert "Bob" Appleby Ragen]],<ref name="Ragen_2012"/> supporting a four-level stack<ref name="Ball_1978"/> in June 1963<!-- Ball writes ca. 1964 -->.<ref name="Friden_EC-130"/> The successor [[Friden EC-132|EC-132]] added a square root function in April 1965.<ref name="Friden_EC-132"/> Around 1966, the [[Monroe Epic]] calculator supported an unnamed input scheme resembling RPN as well.<ref name="Ball_1978"/>