Analog computer

An analog computer (the older, UK spelling analogue was once common) is a computer in which analog information (infinitely variable voltage, etc) is the basic data, instead of the limited discrete values used in digital computing devices. (Obviously, in actuality, all computers are 'analog' at their lowest level, since they are built out of electrical circuits.) Their computational power is limited, but for modelling real world systems, they were important in an age when digital computers had very limited power.