Library Concept
Analog computer
A computing paradigm representing and solving problems with continuously variable physical quantities rather than discrete digital states.
An analog computer solves a problem by building a physical system — mechanical, electrical, or hydraulic — whose continuously variable quantities (voltage, current, shaft rotation) behave according to the same equations as the problem itself, rather than by manipulating discrete digital states. Vannevar Bush’s mechanical differential analyzer (early 1930s) used gear-driven integrators to solve differential equations; George A. Philbrick’s commercial vacuum-tube operational amplifiers (from 1952) made electronic analog computation practical, letting a single op-amp add, subtract, scale, or integrate voltage signals through feedback. Analog computers dominated real-time simulation of continuous dynamic systems — control systems, aircraft and missile guidance, chemical-process modeling — through the 1950s and 60s, before falling out of general use as digital computers became fast and affordable enough to simulate the same continuous systems numerically. The same op-amp-based integrator and summer circuits carried directly into voltage-controlled analog music synthesizers, whose oscillators, filters, and envelope generators are themselves small analog-computing elements repurposed for sound.