The Switch: How the Telegraph, Telephone, and Radio Created the Computer

by Chris McDonald

Digital technology has transformed our world almost beyond recognition over the past four decades. We spend our lives surrounded by laptops, phones, tablets, and video game consoles — not to mention the digital processors that are jam-packed into our appliances and automobiles. We use computers to work, to play, to learn, and to socialize. The Switch tells the story of the humble components that made all of this possible — the transistor and its antecedents, the relay, and the vacuum tube.All three of these devices were originally developed without any thought for their application to computers or computing. Instead, they were created for communication, in order to amplify or control signals sent over a wire or over the air. By repurposing these amplifiers as simple switches, flipped on and off by the presence or absence of an electric signal, later scientists and engineers constructed our digital universe. Yet none of it would have been possible without the telegraph, telephone, and radio.In these pages you'll find a story of the interplay between science and technology, and the surprising ways in which inventions created for one purpose can be adapted to another. The tale is enlivened by the colorful cast of scientists and innovators, from Luigi Galvani to William Shockley, who, whether through brilliant insight or sheer obstinate determination, contributed to the evolution of the digital switch.Chris McDonald studied the history of science and technology at Princeton University. You can find more of his writing at

345 pages, Kindle Edition

Published May 20, 2021