Charles Xavier Thomas de Colmar invented the first commercially successful mechanical calculator in 1820. It was 100 years before mechanical calculators gave way, in the 1930s, to electromechanical calculators, which then quickly gave way to the first general-purpose electronic computer, ENIAC, in 1946. By 1965, Gordon Moore was predicting that engineers would be able to double the number of components on a microchip every two years (and by 1968, he co-founded Intel to help them do so).
Just as Moore predicted, computers continue to become exponentially faster, while their components have become much cheaper. William Nordhaus, an economist at Yale University, examined hundreds of devices—from the first computer to the Apple II to modern PCs—and determined how many basic calculations they could perform every second.