TMRC

TMRC /tmerk'/ n.  The Tech Model Railroad Club at MIT, one
   of the wellsprings of hacker culture.  The 1959 "Dictionary of
   the TMRC Language" compiled by Peter Samson included several terms
   that became basics of the hackish vocabulary (see esp. {foo},
   {mung}, and {frob}).

   By 1962, TMRC's legendary layout was already a marvel of complexity
   (and has grown in the thirty years since; all the features
   described here are still present).  The control system alone
   featured about 1200 relays.  There were {scram switch}es located
   at numerous places around the room that could be thwacked if
   something undesirable was about to occur, such as a train going
   full-bore at an obstruction.  Another feature of the system was a
   digital clock on the dispatch board, which was itself something of
   a wonder in those bygone days before cheap LEDS and seven-segment
   displays.  When someone hit a scram switch the clock stopped and
   the display was replaced with the word `FOO'; at TMRC the scram
   switches are therefore called `foo switches'.

   Steven Levy, in his book "Hackers" (see the
   {Bibliography} in Appendix C), gives a stimulating account of
   those early years.  TMRC's Power and Signals group included most of
   the early PDP-1 hackers and the people who later bacame the core of
   the MIT AI Lab staff.  Thirty years later that connection is still
   very much alive, and this lexicon accordingly includes a number of
   entries from a recent revision of the TMRC dictionary.