Analog computers have been used extensively in the past, for things like tide calculations, but in the semiconductor era things have mostly gone digital. Even where you have analog elements, like DRAM ...

Early computers could perform fairly complex calculations just by arranging a few analog circuits. By choosing appropriate resistor and capacitor values, arithmetic summers, integrators, and ...

We are always impressed with something so simple can actually be so complex. For example, what would you think goes into an analog computer? Of course, a “real” analog computer has opamps that can do ...