n. Commonly used abbreviation for Digital Equipment Corporation, later deprecated by DEC itself in favor of “Digital” and now entirely obsolete following the buyout by Compaq. Before the killer micro revolution of the late 1980s, hackerdom was closely symbiotic with DEC's pioneering timesharing machines. The first of the group of cultures described by this lexicon nucleated around the PDP-1 (see TMRC). Subsequently, the PDP-6, PDP-10, PDP-20, PDP-11 and VAX were all foci of large and important hackerdoms, and DEC machines long dominated the ARPANET and Internet machine population. DEC was the technological leader of the minicomputer era (roughly 1967 to 1987), but its failure to embrace microcomputers and Unix early cost it heavily in profits and prestige after silicon got cheap. Nevertheless, the microprocessor design tradition owes a major debt to the PDP-11 instruction set, and every one of the major general-purpose microcomputer OSs so far (CP/M, MS-DOS, Unix, OS/2, Windows NT) was either genetically descended from a DEC OS, or incubated on DEC hardware, or both. Accordingly, DEC was for many years still regarded with a certain wry affection even among many hackers too young to have grown up on DEC machines.