Enter vs. =

[ttw]

Having taught both high school and college students how to use calculators for math and business classes, I have formed a few opinions. In general, RPN takes about 1/2 the number of keystrokes that algebraic does for the same formula. Second, most students find RPN rather natural; it's the way one evaluates when using pencil and paper. The poorer students found RPN even more natural, probably because they had more trouble with abstract symbols.

Back in the 1960s, outlined the computation tree for some expressions using three-address, two-address, one-address, and stack notation for computation. All four of these did exist in hardware. Three address (like a Cray) was slight better than two-address (IBM 360) which was slightly better than single address (CDC 1604) which was slight better than stack (Burroughs B8500). The B8500 could compile a bit faster. Thus the gain in RPN over algebraic was probably due to notational simplicity, not data flow.