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:
“Men must speak English who can write Sanskrit; they must speak a modern language who write, perchance, an ancient and universal one.”
—Henry David Thoreau (1817–1862)