I well recall, back in undergrad days (mid-60s), all the engineering students proudly sported ‘quick-draw’ POST sliderule holsters, for such was the way one announced one’s nerdship to the rest of the student world. Then, whilst engaged as a lab tech in 1969, everyone suddenly showed up carrying slick little Hewlett-Packard electronic calculators (the HP-35 model started things off). They, of course, used RPN (‘Reverse Polish Notation’) logic for calculations. Texas Instruments used regular algebraic logic in their small pocket-calculator counterparts and for a number of years it was a fierce and ferocious competition between HP and TI to capture market share in this new area of technology. I personally preferred the RPN system and got an HP-35, followed by an HP-45 and even later one of the first graphing calculators for advanced trig. Today, the sky’s the limit and everyone who used to rely on old-fashioned manual calculations has one or several of these handy gizmos. Me? I still have my HP-35 and HP-45; they’re now both museum-quality artifacts but they both still work like new! TI eventually ‘won’ the pocket calculator market, a distinction it still holds today.