Computers were invented to ‘‘compute’’: to solve ‘‘complex mathematical problems,’’ as the dictionary still defines that word. They still do that, but that is not why we are living in an ‘‘Information Age.’’ That reflects other things that computers do: store and retrieve data, manage networks of communications, process text, generate and manipulate images and sounds, fly air and space craft, and so on. Deep inside a computer are circuits that do those things by transforming them into a mathematical language. But most of us never see the equations, and few of us would understand them if we did. Most of us, nevertheless, participate in this digital culture, whether by using an ATM card, composing and printing an office newsletter, calling a mail-order house on a toll-free number and ordering some clothes for next-day delivery, or shopping at a mega-mall where the inventory is replenished ‘‘just-in-time.’’ For these and many other applications, we can use all the power of this invention without ever seeing an equation. As far as the public face is concerned, ‘‘computing’’ is the least important thing that computers do.
But it was to solve equations that the electronic digital computer was invented. The word ‘‘computer’’ originally meant a person who solved equations; it was only around 1945 that the name was carried over to machinery.
That an invention should find a place in society unforeseen by its inventors is not surprising.3 The story of the computer illustrates that. It is not that the computer ended up not being used for calculation—it is used for calculation by most practicing scientists and engineers today. That much, at least, the computer’s inventors predicted. But people found ways to get the invention to do a lot more. How they did that, transforming the mathematical engines of the 1940s to the networked information appliance of the 1990s, is the subject of this book.