In Modern CPUs
CPU designers sometimes incorporate one or more undocumented machine code instructions, which exist for testing purposes. These instructions are not intended to be executed during real-world operation of the CPU. When these instructions are actually executed during a program, they have unusual side-effects.
The old "Halt and Catch Fire" instruction and HCF mnemonic are sometimes appropriated by users who discovered these instructions, as a humorous way of expressing that the unintended execution of such an instruction causes the system to fail to perform its normal functions.
Read more about this topic: Halt And Catch Fire
Famous quotes containing the word modern:
“These modern ingenious sciences and arts do not affect me as those more venerable arts of hunting and fishing, and even of husbandry in its primitive and simple form; as ancient and honorable trades as the sun and moon and winds pursue, coeval with the faculties of man, and invented when these were invented. We do not know their John Gutenberg, or Richard Arkwright, though the poets would fain make them to have been gradually learned and taught.”
—Henry David Thoreau (1817–1862)