V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

HCF
       Hybrid Coordination Function (MAC, 802.11a)


The Jargon File (version 4.4.7, 29 Dec 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.


The Free On-line Dictionary of Computing (30 December 2018):

HCF

   1.  Host Command Facility.

   2.  Halt and Catch Fire.

   [Jargon File]

   (1999-01-24)