Young'uns and switches
Concur with the various mentions of minimum current. Once was a time when _serious_ switch interfaces made sure the combo of pullup resistor value and the B+ on the other end kept things shiny :-)
But it's not just the folklore on electrical stuff that gets forgotten/ignored. After several sessions of an EE lying through his teeth about a particular switch being readable at all (despite being on the 10th bit of an 8-bit port), I got to confront the physical design. The ME had used a stamped lever to bear directly on the little button of a PCB-mounted microswitch, rather than the must-be-50-years-old practice of having something with a bit of compliance between the fragile, low-travel switch and the big-bad-world of industrial equipment. But by the time I could get anybody to listen (Go away, Gramps, you're just a programmer), it was too late, so they just edited the spec-sheet to no longer promise any mitigation of that particular failure mode.
Biting the hand that feeds IT
