<P> The Aircraft Navigation Computer Heathkit OC - 1401 / OCW - 1401 used five - level RPN in 1978 . </P> <P> Soviet programmable calculators (MK - 52, MK - 61, B3 - 34 and earlier B3 - 21 models) used reverse Polish notation for both automatic mode and programming . Modern Russian calculators MK - 161 and MK - 152, designed and manufactured in Novosibirsk since 2007 and offered by Semico, are backward compatible with them . Their extended architecture is also based on reverse Polish notation . </P> <P> Existing implementations using reverse Polish notation include: </P> <Ul> <Li> Any stack - oriented programming language, such as: <Ul> <Li> Forth </Li> <Li> Factor </Li> <Li> PostScript page description language </Li> <Li> BibTeX </Li> <Li> Befunge </Li> <Li> Joy </Li> <Li> IPTSCRAE </Li> <Li> Lotus 1 - 2 - 3 and Lotus Symphony formulas </Li> <Li> RPL (aka Reverse Polish Language), a programming language for the Commodore PET around 1979 / 1981 </Li> <Li> RPL (aka Reverse Polish Lisp), a programming language for Hewlett - Packard calculators between 1984 and 2015 </Li> <Li> RPNL (Reverse Polish Notation Language) </Li> </Ul> </Li> <Li> Hardware calculators: <Ul> <Li> Some Hewlett - Packard science / engineering and business / finance calculators </Li> <Li> Semico calculators </Li> <Li> SwissMicros calculators </Li> </Ul> </Li> <Li> Software calculators: <Ul> <Li> Mac OS X Calculator </Li> <Li> Several Apple iPhone applications e.g. "reverse polish notation calculator" </Li> <Li> Several Android applications e.g. "RealCalc" </Li> <Li> Several Windows 10 Mobile applications e.g. "RPN9" </Li> <Li> Unix system calculator program dc </Li> <Li> Emacs lisp library package calc </Li> <Li> Xorg calculator (xcalc) </Li> <Li> grpn scientific / engineering calculator using the GIMP Toolkit (GTK+) </Li> <Li> F - Correlatives in MultiValue dictionary items </Li> <Li> RRDtool, a widely used tabulating and graphing software </Li> <Li> grdmath, a program for algebraic operations on NetCDF grids, part of Generic Mapping Tools (GMT) suite </Li> <Li> galculator, a GTK desktop calculator </Li> <Li> Mouseless Stack - Calculator scientific / engineering calculator including complex numbers . </Li> </Ul> </Li> </Ul>

Polish and reverse polish notations in data structure