HP famously built the first portable scientific calculator, the HP-35, although its reverse-Polish notation (RPN) might be a bit of a head-scratcher to those of us who came up in the TI world of ...
the HP-01 did not use RPN. For such a hefty price, these calculators didn’t do much. They were generally “four-bangers” with a few extra features, but they were no scientific calculators by ...