A bit more on sliderules and calculators. One of my constant memories is of my Dad, an aeronautical engineer, sitting on his easy chair, sliderule in hand and quadrille tablet in his lap. That’s how he did his creative engineering – away from the hubbub of the workplace. Of course there were statistics and computer guys at “the plant,” but at home he would be deeply lost in thought on one thing or another, working on his own. Then one day in the early 1970’s, when I was visiting from across the country, I noticed he had an HP programmable hand calculator (which used RPN). He had programmed in certain key formulas that he commonly used. So even an “old guy” (he was then about 60) could adapt to the handheld calculator and keep himself independent of (well not completely dependent on) the tech guys. Also, believe it or not, the calculus was invented long ago. I saw his textbooks from college in the 1930’s so it must have already been invented by then (:-)). So he knew how to put those new toys to good use.