They're becoming less common, but mechanical automobile (and bicycle) odometers are little mechanical computers of a sort. Baseball and softball umpires (especi

They're becoming less common, but mechanical automobile (and bicycle) odometers are little mechanical computers of a sort. Baseball and softball umpires (especially for rec leagues, not sure about professional games) often use a "clicker" (https://www.amazon.com/Easton-Umpire-Indicator/dp/B07BYX8XQL https://www.amazon.com/Easton-Umpire-Indicator/dp/B07BYX8XQL for example) to keep count of balls and strikes.