If you like Nixie tubes and/or DIY calculators, checkout this interesting talk from the HP Handheld Conference in Orlando last month by [Eric Smith] from Brouhaha and [John Doran] from Time ...
Of course, HP calculators used RPN, but if you grew up with a slide rule that’s fine. For everyone else, it is usually a bit of a learning curve. Also, as great as the HP41C was, it didn’t ...