Celtics-Sixers rivalry

The second round of the NBA playoffs opens tonight when Boston hosts Philadelphia in Game 1 of their Eastern Conference semi-finals. Both teams won their opening series without the benefit of homecourt advantage and closed the deal in last-second Game 6 finishes on Thursday. The Celtics and Sixers have had some epic playoff battles in their history, especially 1981 and 1982. TheSportsNotebook previews the 2012 edition of this rivalry…