“It is the machines that make life complicated, at the
same time that they impose on it a high tempo.”
—Carl Lotus Becker
4: Computer Cousins—Analog
and Digital
There are many thousands of computers in operation today—in enough different outward varieties to present a hopeless classification task to the confused onlooker. Actually there are only two basic types of computing machines, the analog and the digital. There is also a third computer, an analog-digital hybrid that makes use of the better features of each to do certain jobs more effectively.
The distinction between basic types is clear-cut and may be explained in very simple terms. Again we go to the dictionary for a starting point. Webster says: “Analogue.—That which is analogous to some other thing.” Even without the terminal ue, the analog computer is based on the principle of analogy. It is actually a model of the problem we wish to solve. A tape measure is an analog device; so is a slide rule or the speedometer in your car. These of course are very simple analogs, but the principle of the more complex ones is the same. The analog computer, then, simulates a physical problem and deals in quantities which it can measure.
Some writers feel that the analog machine is not a computer at all in the strict sense of the word, but actually a laboratory model of a physical system which may be studied and measured to learn certain implicit facts.
Minneapolis-Honeywell Computer Center
A multimillion dollar aerospace computer facility. On left is an array of 16 analog computers; at right is a large digital data-processing system.
The facility can perform scientific and business tasks simultaneously.