“After many years of faithful service, the magic switch now sits in disgrace on a counter somewhere.”

(It’s Halloween Week on Unsung, where we’re sharing scary, spooky, and creepy stories.) This story is a classic Jargon File campfire mystery: Some years ago, I […] was snooping around in the cabinets that housed the MIT AI Lab’s PDP-10, and noticed a little switch glued to the frame of one cabinet. It was obviously a homebrew job, added by one of the lab’s hardware hackers (no one knows who). You don’t touch an unknown switch on a computer without knowing what it does, because you might crash the computer. The switch was labeled in a most unhelpful way. It had two positions, and scrawled in pencil on the metal switch body were the words “magic” and “more magic.” The switch was in the “more magic” position. I called another hacker over to look at it. He had never seen the switch before either. Closer examination revealed that the switch had only one wire running to it! The other end of the wire did disappear into the maze of wires inside the computer, but it’s a basic fact of…