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

6.001

    /siks dub*l oh wun/, /dub*l oh wun/ or rarely
   /siks dub*l oh fun/ MIT's introductory computer class for
   majors, known for its intensity.  Developed by Gerald
   Sussman and Hal Abelson, the course is taught in Scheme
   and introduces recursion, higher-order functions,
   object-oriented programming and much more.  Students who
   grasp the metacircular interpreter gain entry into the
   Knights of the Lambda-Calculus.  6.001 has been exported to
   several other colleges, sometimes successfully.  The textbook,
   "Structure and Interpretation of Computer Programs", written
   with Julie Sussman is a classic that can be found on the
   shelves of many computer scientists, whether they took the
   course or not.  Legendary characters from the class, problem
   sets, and book include the wise Alyssa P. Hacker, Ben
   Bitdiddle, Lem E. Tweakit and Eva Lu Ator, the careless Louis
   Reasoner and Captain Abstraction.

   (1994-11-22)