I try not to cut-and-paste press releases, but I hope you'll excuse me in this case. I can't resist HP-35 trivia:
PALO ALTO, Calif., April 14, 2009 - HP today announced that IEEE, the world's largest technical professional association, has awarded HP the prestigious IEEE Milestone in Electrical Engineering and Computing award for its HP-35 Scientific Calculator.
Introduced in 1972, the HP-35 was the world's first handheld-sized scientific calculator. An instant hit, the HP-35 ultimately made the slide rule, which had previously been used by generations of engineers and scientists, obsolete.
• The HP-35, named for its 35 keys, was the first handheld calculator to perform transcendental functions such as trigonometric, logarithmic and exponential functions.
• At the time, contemporary calculators could only perform four basic functions - addition, subtraction, multiplication and division.
• The now classic "Reverse Polish Notation" (RPN) first used in the HP-35 has become the most efficient way known to computer science for evaluating mathematical expressions.
• In the first three years after its introduction in 1972, sales of the HP-35 Scientific Calculator exceeded 300,000 units.
• Forbes ASAP named HP 35 as one of the 20 "all time products" that have changed the world.
• It was the world's first handheld scientific calculator with a LED display.
• HP-35 has traveled to the top of Mt. Everest for use in altitude and navigation calculations.
• HP-35 is regularly used to navigate ships.
• HP-35 has been used by astronauts aboard spacecraft to calculate the exact angle of re-entry into the Earth's atmosphere.