Multivac is the name of a fictional supercomputer appearing in over a dozen science fiction stories by American writer Isaac Asimov. Asimov's depiction of Multivac, a mainframe computer accessible by terminal, originally by specialists using machine code and later by any user, and used for directing the global economy and humanity's development, has been seen as the defining conceptualization of the genre of computers for the period (1950s–1960s). Multivac has been described as the direct ancestor of HAL 9000. Description Like most of the technologies Asimov describes in his fiction, Multivac's exact specifications vary among appearances. In all cases, it is a government-run computer that answers questions posed using natural language, and it is usually buried deep underground for security purposes. According to his autobiography In Memory Yet Green, Asimov coined the name in imitation of UNIVAC, an early mainframe computer. Asimov had assumed the name "Univac" denoted a computer with a single vacuum tube (it actually is an acronym for "Universal Automatic Computer"), and on the basis that a computer with many such tubes would be more powerful, called his fictional computer "Multivac". His later short story "The Last Question", however, expands the AC suffix to be "analog computer". However, Asimov never settles on a particular size for the computer (except for mentioning it is very large):86 or the supporting facilities around it. In the short story "Franchise" it is described as half a mile long (~800 meters) and three stories high, at least as far as the general public knows, while "All the Troubles of the World" states it fills all of Washington D.C.. There are frequent mentions of corridors and people inside Multivac. Unlike the artificial intelligences portrayed in his Robot series, Multivac's early interface is mechanized and impersonal, consisting of complex command consoles few humans can operate. In "The Last Question", Multivac is shown as having a life of many thousands of years, growing ever more enormous with each section of the story, which can explain its different reported sizes as occurring further down the internal timeline of the overarching story.:20 Storylines Multivac appeared in over a dozen science fiction stories by American writer Isaac Asimov, some of which have entered the popular imagination. In the early Multivac story, "Franchise", Multivac chooses a single "most representative" person from the population of the United States, whom the computer then interrogates to determine the country's overall orientation. All