Some years ago, I was snooping around in the cabinets that hous
ed the
MIT AI Lab' s
PDP-10, and notic
ed a little switch glu
ed to the frame of one cabinet. It was obviously a homebrew job, add
ed 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 labell
ed in a most unhelpful way. It had two positions, and scrawl
ed in pencil on the metal switch body were the words "magic" and "more magic". The switch was in the "more magic" position. I call
ed another hacker over to look at it. He had never seen the switch before either. Closer examination reveal
ed 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 electricity that a switch can' t do anything unless there are two wires connect
ed to it. This switch had a wire connect
ed on one side and no wire on its other side. It was clear that this switch was someone' s idea of a silly joke. Convinc
ed by our reasoning that the switch was inoperative, we flipp
ed it. The computer instantly crash
ed. Imagine our utter astonishment. We wrote it off as coincidence, but nevertheless restor
ed the switch to the "more magic" position before reviving the computer. A year later, I told this story to yet another hacker, {David Moon} as I recall. He clearly doubt
ed my sanity, or suspect
ed me of a supernatural belief in the power of this switch, or perhaps thought I was fooling him with a bogus saga. To prove it to him, I show
ed him the very switch, still glu
ed to the cabinet frame with only one wire connect
ed to it, still in the "more magic" position. We scrutiniz
ed the switch and its lone connection, and found that the other end of the wire, though connect
ed to the computer wiring, was connect
ed to a ground pin. That clearly made the switch doubly useless: not only was it electrically nonoperative, but it was connect
ed to a place that couldn' t affect anything anyway. So we flipp
ed the switch. The computer promptly crash
ed. This time we ran for Richard Greenblatt, a long-time
MIT hacker, who was close at hand. He had never notic
ed the switch before, either. He inspect
ed it, conclud
ed it was useless, got some diagonal cutters and
diked it out. We then reviv
ed the computer and it has run fine ever since. We still don' t know how the switch crash
ed the machine. There is a theory that some circuit near the ground pin was marginal, and flipping the switch chang
ed the electrical capacitance enough to upset the circuit as millionth-of-a-second pulses went through it. But we' ll never know for sure all we can really say is that the switch was
magic. I still have that switch in my basement. Maybe I' m silly, but I usually keep it set on "more magic".
GLS (1995-02-22)
In addition suitable contents:
[ 2 ] [ = ] [ ad ] [ af ] [ ag ] [ AI ] [ al ] [ am ] [ an ] [ app ] [ ar ] [ arc ] [ arg ] [ as ] [ ash ] [ at ] [ au ] [ av ] [ aw ] [ az ] [ B ] [ b ] [ ba ] [ base ] [ be ] [ bell ] [ bi ] [ blat ] [ bo ] [ br ] [ bt ] [ bv ] [ by ] [ C ] [ ca ] [ ch ] [ char ] [ ci ] [ circuit ] [ ck ] [ cl ] [ co ] [ com ] [ computer ] [ con ] [ connect ] [ cr ] [ crash ] [ cu ] [ D ] [ dd ] [ de ] [ dike ] [ do ] [ DP ] [ du ] [ ec ] [ ed ] [ ee ] [ er ] [ era ] [ es ] [ et ] [ fact ] [ fi ] [ file ] [ fo ] [ for ] [ fr ] [ frame ] [ G ] [ ga ] [ ge ] [ gh ] [ gi ] [ GL ] [ gl ] [ GLS ] [ glue ] [ gr ] [ Green ] [ gu ] [ h ] [ hack ] [ hacker ] [ hang ] [ hardware ] [ hat ] [ hing ] [ hm ] [ hr ] [ ht ] [ id ] [ ie ] [ il ] [ in ] [ inc ] [ int ] [ io ] [ ir ] [ is ] [ IT ] [ it ] [ jo ] [ job ] [ ke ] [ kn ] [ la ] [ ld ] [ Lex ] [ li ] [ lose ] [ loser ] [ ls ] [ lu ] [ ly ] [ M ] [ ma ] [ machine ] [ magic ] [ marginal ] [ meta ] [ mil ] [ mill ] [ MIT ] [ MIT AI Lab ] [ mo ] [ mod ] [ module ] [ mp ] [ my ] [ na ] [ nc ] [ ne ] [ net ] [ ng ] [ ni ] [ nl ] [ nn ] [ no ] [ ns ] [ om ] [ op ] [ pa ] [ PD ] [ PDP ] [ PDP-10 ] [ pe ] [ pf ] [ ph ] [ ping ] [ pl ] [ pr ] [ pt ] [ query ] [ rc ] [ re ] [ real ] [ rl ] [ ro ] [ ru ] [ run ] [ S ] [ sa ] [ say ] [ sc ] [ se ] [ set ] [ sh ] [ si ] [ sit ] [ sl ] [ sn ] [ so ] [ spec ] [ st ] [ store ] [ su ] [ switch ] [ T ] [ tc ] [ th ] [ theory ] [ to ] [ tr ] [ tt ] [ tw ] [ ua ] [ ug ] [ up ] [ us ] [ ve ] [ vi ] [ win ] [ word ] [ ws ] [ Y ] [ ye ] [ yt ]