RPN Calculators Calculators in Reverse Polish Notation, but with different approaches, different functions, different methods. http://www.dsv.nl/~ovide/rpn.htm

User Friendly the Comic Strip about RPN. A good way of explaining RPN with three picture frames. (Note: Erwin is an AI entity that frequently has been moved to different computers and his previous home was a Sun Workstation.) http://www.userfriendly.org/cartoons/archives/99aug/19990826.html

Eric Smith's HP Calculator Info Technically page about older HP calculators with simulators for HP-41 and 45 calculators. With links to other calculator-related pages, journal articles, and US patents. http://www.brouhaha.com/~eric/hpcalc/

Scientific Calculators Online Texas Instrument scientific and graphing calculators. http://www.scientific-calculators.com