Home > AI, History, Logic > Reverse Polish Notation (RPN)

Reverse Polish Notation (RPN)

The Financial Times recently published a correspondence on Reverse Polish Notation, including this letter from one Peter Jaeger of Tokyo, Japan (published on 2011-09-30):

Sir, Your reader Chris Ludlam describes the input method of his HP12c as “reverse logic”. The correct term is “Reverse Polish”, which is not only far more colourful, but also gives credit to Jan Lukasiewicz, the logician who invented the original Polish Notation which American mathematicians later adapted for computers.”

While it is correct to say that American mathematicians adapted Reverse Polish Notation (RPN) for computers, this is not the whole story.  The first person to speak publicly about using RPN for computer architectures was Australian –  Charles Hamblin, an Australian philosopher and computer pioneer, speaking at a computer conference held in Salisbury, South Australia, in June 1957.  (This was billed as “The First Australian Computer Conference”, but an earlier one had been held in 1951.)   Hamblin’s work was published in the conference proceedings and later in a refereed article in the Computer Journal in 1962.   Among the attendees at that conference was the British statistician and computer pioneer Maurice Wilkes, who later won an AM Turing Award (in 1967), as well as delegates from computer manufacturing companies.

The first computer manufacturing company to announce deployment of RPN in a commercial computer architecture was British – the English Electric Company (EEC), in their KDF9 machine, announced in 1960 and delivered in 1963.   Burroughs, an American computer company, also delivered a computer using RPN in 1963, the Burroughs B5000, but this machine was only announced in 1961.   Robert Barton, chief architect of the B5000, later wrote that he developed RPN independently of Hamblin, sometime in 1958.

So the first person to talk publicly about applying RPN to computers was Australian and the first computer company to say publicly they would actually do so was British.   Not everything in computing happens first in the USA!


R. S. Barton [1970]: Ideas for computer systems organization: a personal survey. pp. 7-16 of: J. S. Jou (Editor): Software Engineering: Volume 1: Proceedings of the Third Symposium on Computer and Information Sciences held in Miami Beach, Florida, December 1969. New York, NY, USA: Academic Press.

C. L. Hamblin [1957]: An addressless coding scheme based on mathematical notation. Proceedings of the First Australian Conference on Computing and Data Processing, Salisbury, South Australia: Weapons Research Establishment, June 1957.

C. L. Hamblin [1962]: Translation to and from Polish notation. Computer Journal, 5: 210-213.

Categories: AI, History, Logic
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