George Dyson has written a fascinating book about the building of the first stored-program computer by John von Neumann and his colleagues at the Institute of Advanced Studies at Princeton. After I’d finished the book I had an email exchange with him, an edited version of which appears in this morning’s Observer.

Once upon a time, a “computer” was a human being, usually female, who did calculations set for her by men in suits. Then, in the 1940s, something happened: computers became machines based on electronics. The switch had awesome implications; in the end, it spawned a technology that became inextricably woven into the fabric of late-20th- and early 21st-century life and is now indispensable. If the billions of (mostly unseen) computers that now run our industrialised support systems were suddenly to stop working, then our societies would very rapidly grind to a halt.

So the question of where this Promethean force sprang from is an intriguing one, as interesting in its way as the origins of the industrial revolution…

Photograph shows the book on sale in Heffers bookshop in Cambridge yesterday.