killer micro n. [popularized by Eugene Brooks] A microprocessor-based
   machine that infringes on mini, mainframe, or supercomputer performance
   turf. Often heard in "No one will survive the attack of the killer
   micros!", the battle cry of the downsizers. Used esp. of RISC
   architectures.

   The popularity of the phrase `attack of the killer micros' is
   doubtless reinforced by the title of the movie "Attack Of The Killer
   Tomatoes" (one of the {canonical} examples of so-bad-it's-wonderful
   among hackers). This has even more {flavor} now that killer micros have
   gone on the offensive not just individually (in workstations) but in
   hordes (within massively parallel computers).

   [1996 update: Eugene Brooks was right. Since this term first entered
   the Jargon File in 1990, the minicomputer has effectively vanished, the
   {mainframe} sector is in deep and apparently terminal decline (with IBM
   but a shadow of its former self), and even the supercomputer business
   has contracted into a smaller niche. It's networked killer micros as far
   as the eye can see. --ESR]


Source: The Jargon File