From "fortune -m HCF" (alternatively, look up "HCF" in the Jargon File):

> Proposed Additions to the PDP-11 Instruction Set:
> 
> DC      Divide and Conquer
> DMPK    Destroy Memory Protect Key
> DO      Divide and Overflow
> EMPC    Emulate Pocket Calculator
> EPI     Execute Programmer Immediately
> EROS    Erase Read Only Storage
> EXCE    Execute Customer Engineer
> HCF     Halt and Catch Fire
> IBP     Insert Bug and Proceed
> INSQSW  Insert into queue somewhere (for FINO queues [First in never out])
> PBC     Print and Break Chain
> PDSK    Punch Disk

HCF stands for "Halt and Catch Fire"; it indicates where you can go to
light up.