hcf

from Jargon File (4.4.4, 14 Aug 2003)

HCF
 /H.C.F/, n.

   Mnemonic for `Halt and Catch Fire', any of several undocumented and
   semi-mythical machine instructions with destructive side-effects,
   supposedly included for test purposes on several well-known
   architectures going as far back as the IBM 360. The MC6800
   microprocessor was the first for which an HCF opcode became widely
   known. This instruction caused the processor to {toggle} a subset of
   the bus lines as rapidly as it could; in some configurations this
   could actually cause lines to burn up. Compare {killer poke}.

from The Free On-line Dictionary of Computing (8 July 2008)

HCF

   1. <operating system> {Host Command Facility}.

   2. <architecture> {Halt and Catch Fire}.

   [{Jargon File}]

   (1999-01-24)

from V.E.R.A. -- Virtual Entity of Relevant Acronyms (June 2006)

HCF
       Hybrid Coordination Function (MAC, 802.11a)