1. <computer> HAL 9000, the murdering computer on the spaceship in the science fiction classic "2001, A Space Odyssey" by Arthur C. Clark.
"HAL" is "IBM" with each letter changed to the one before and there is an unconfirmed rumour that 9000 is the sum of the various IBM computer numbers that were in service at the time. However, in the sequel "2010", Clarke emphatically denies that HAL's name is supposed to be "one step ahead of IBM". It is, rather, short for "heuristic algorithm".
2. <operating system> Hardware Abstraction Layer.
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Nearby terms: hairy ball « HAKMEM « hakspek « HAL » half-duplex » halftone » HALGOL