HP-11C

The HP-11C is a scientific programmable calculator with 63 lines of permanent program space. It provided label addressing (0-9 and A-E), subroutines (nestable to four levels), eight conditional tests, increment/decrement loops, and two flags. For program editing, the calculator featured implied insert (instructions entered didn't overwrite the current instruction) and deletion via the backspace key.
Other features random number generator, hyperbolic and inverse hyperbolic trig functions, probability (combinations and permutations), factorial, % change, and absolute value.
This calculator uses the Reverse Polish Notation (RPN was proposed in 1954 by Burks, Warren, and Wright and reinvented by F. L. Bauer and E. W. Dijkstra later). This notation is an efficient data entry method that eliminates the need to enter parentheses in equations.

Owner's handbook: rear view. Italian version.

Owner's handbook: random page.