The Free On-line Dictionary of Computing (30 December 2018):

Semi-Automatic Ground Environment

    (SAGE) The computer system of the old US Norad air
   defence system.  SAGE was ground-breaking in many ways, such
   as being one of the first very large software projects and the
   first real-time system.

   MIT Lincoln Laboratory developed SAGE and MITRE
   Corporation was responsible for system engineering and
   implementation oversight.

   (http://togger.com/),
   (http://jps.net/ethelen/sage.html),
   (http://eskimo.com/%7Ewow-ray/sage28.html).

   [Confirm?  Dates?  Connection with MIT Research Laboratory for
   Electronics?]

   (1999-12-16)