"Hal (for Heuristically programmed Algorithmic computer, no less) was a masterwork of the third computer breakthrough. These seemed to occur at intervals of twenty years, and the thought that another one was now imminent already worried a great many people. The first had been in the 1940s, when the long-obsolete vacuum tube had made possible such clumsy, high-speed morons as ENIAC and its successors. Then, in the 1960s, solid-state microelectronics had been perfected. With its advent, it was clear that artificial intelligences at least as powerful as Man's need be no larger than office desks…In the 1980s, Minsky and Good had shown how neural networks could be generated automatically — self replicated — in accordance with any arbitrary learning program. Artificial brains could be grown by a process strikingly analogous to the development of a human brain."