dtss

from The Free On-line Dictionary of Computing (8 July 2008)
DTSS

   <operating system> The first commercial {time-sharing} system,
   created by {Dartmouth College} and sold by {General Electric}
   around 1967.

   GE's Information Service Divsion (ISD) marketed DTSS which was
   running on a system called {GE-265} (a combination of the
   {front-end processor} the {Datanet-30} and the {GE-235}).

   DTSS was ported (and significantly improved by GE ISD around
   1965-1966 on a combination of DN-30 and {GE-635}).  This
   proprietary system, called Mk-II, later improved by GE and
   renamed Mk-III, is still working today (1997) as part of the
   GE service bureau that also includes {IBM} and {Unix}
   computers.

   (1997-09-16)