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:
“Chaucer is fresh and modern still, and no dust settles on his true passages. It lightens along the line, and we are reminded that flowers have bloomed, and birds sung, and hearts beaten in England. Before the earnest gaze of the reader, the rust and moss of time gradually drop off, and the original green life is revealed. He was a homely and domestic man, and did breathe quite as modern men do.”
—Henry David Thoreau (1817–1862)