Lisp and Polish notation [was RE: Calculators]

Rich Alderson wrote: calculators. A few calculators used RPN either internally (for evaluation of algebraically-entered expressions), or as the means for expression entry before HP came out with the 9100A. The Friden 130 was the first calculator to use RPN entry. The Mathatronics Mathatron used RPN internally. Some really complex logic allowed it to evaluate algebraic expressions entered in "as written" form. The algebraic expressions were converted to RPN internally and evaluated on the fly. The Monroe EPIC 2000/3000 calculators also used RPN entry. All of these machines were implemented using discrete transistors and (delay line|magnetic core) for memory. The HP 9100A was implemented with the same technologies, but it was done so elegantly, and in a package that was much smaller and so much more capable than any of its predecessors. That's what made HP famous as the "inventor" of RPN in the context of calculators. Rick Bensene The Old Calculator Museum http://oldcalculatormuseum.com