Civilization advances by extending the number of important operations which we can perform without thinking about them.
–Alfred North Whitehead
It’s fascinating to see how far we’ve come in just a few decades. Check out this old US Navy film from 1953 on how a mechanical firing computer works. They’re using custom-cut gears and cams to physically calculate algebraic and trigonometric functions. People (okay, this is 1953 — “men”) enter data by turning wheels and moving levers, and mechanical linkages in a purpose-built computer the size of a refrigerator turn this into firing solutions.
These days, a microcontroller priced lower than a cheap cup of coffee could do all of this easily. A smartphone wouldn’t even notice the extra computational load, and could effortlessly handle a fleet’s worth of such computations while showing you the HD video of how it used to be done.