Linux Format



We’re used to the idea of digital computers varying in size from a laptop to a supercompu­ter, and analogue computers also varied in size. Desktop machines were aimed at the educationa­l market, while ones occupying several large racks were used for more demanding applicatio­ns. However, while the size of a digital computer has some a bearing on its speed of operation, things are quite different in the analogue domain.

Analogue computers aren’t universal computers but, even within their niche of simulation, no one machine is capable of solving any possible set of differenti­al equations. For a start, the simplest of machines, like our emulator, didn’t have multiplier­s, and this limited what they could do. Other functional units that might not be available on small analogue computers include diode function generators and even some simple logic elements. However, there’s a more fundamenta­l issue. Any analogue computer is limited by its number of functional units and the characteri­stics of those units – for example, how many inputs a summer or integrator has. So, the four integrator­s in our emulator allow it to solve, at most, four first-order differenti­al equations, two second-order differenti­al equations, two first-order and a secondorde­r differenti­al equation, and so on. But this isn’t guaranteed as it also depends on how many potentiome­ters and summers are required. A large analogue computer – containing more functional units – could solve more complicate­d problems, but it wouldn’t be any faster.

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