Wiring terminals 300 ft. from the computer

[Ken Lerman]

[...]
->Not exactly nothing.  Try this experiment at home, hook up about 200-300 
->feet of twisted pair to the RD and TD pins of your favorite 9600 baud 
->terminal.  Leave the far end disconnected (this is the trick).  Now type 
->something on the keyboard.  The last time I tried this the unterminated 
->cable run magically echo-ed every character as if it was really attached 
->to a host port.  Can you say "inductive coupling"?  
->-- 
->bruce at segue.com, ism.isc.com!segue!bruce, aero.org!segue!bruce

Or, more likely, capacitive coupling.  Inductive coupling would
require that there be a current path back from each wire.  Of course,
that current path could be capacitive and you could have a combination
of inductive and capacitive coupling, but in this case, I would expect
capacitive coupling to be the "culprit".

Ken