[Part 1 of the HP Calc
I recently started a super-geeky side hobby of collecting vintage calculators and got my hands on a pair of HP calcs. The more I learned about the internals of the devices, the more intrigued I was. Jacques Laporte has an absolutely wonderful site going into crazy detail.
In 1972, Hewlett-Packard amazed the engineering world and killed the slide rule with the release of the HP-35 calculator; the very first hand-held electronic scientific calculator. Most astonishing was that apparently even cute girls loved RPN and were impressed by the device’s ability to do transcendental logarithm and trigonometry functions.