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:
“The poverty of our century is unlike that of any other. It is not, as poverty was before, the result of natural scarcity, but of a set of priorities imposed upon the rest of the world by the rich. Consequently, the modern poor are not pitied ... but written off as trash. The twentieth-century consumer economy has produced the first culture for which a beggar is a reminder of nothing.”
—John Berger (b. 1926)