 The black and white episodes of the first season were last re-run on August 21, 1970, just before NET was replaced by PBS., almost all of the 1979–2001 "second series" episodes are still in active rotation on a number of PBS stations.The only exception is the week-long "Conflict" series (episodes #1521–#1525), first aired during the week of November 7–11, 1983.