Drucker points out that this was only the beginning of the chain that led to computers as we know them today. Hermann Hollerith came up with the idea of the punched card that converted numbers to instruction. The invention of the CRT by American Lee de Forest in 1906, followed by the creation of symbolic logic by Bertrand Russell and Alfred North Whitehead, was a necessary predecessor technology. Symbolic logic led to programming, thus permitting the expression of logical concepts in numerical form, which found initial application in programming antiaircraft gunnery. “By 1918, in other words, all the knowledge needed to develop the computer was available. The first computer became operational in 1946.” But the PC was still thirty years in the future. At first the ENIAC, produced during the Second Would War and developed subsequently by the Bendix Corp., was merely a scientific curiosity. Then came the advancement of solid-state technology in the 1960s, led by the transistor technology, and the computer became reasonably viable in large-scale commercial/scientific applications. And it was not until advances in printed circuitry, chip and microchip technology were realized that PCs took on broad application and could be commercially developed. In all there was a gap of about 150 years from concept to product.