LOS ANGELES – William Blinn, a screenwriter for the landmark TV projects “Brian’s Song” and “Roots” and the Prince film “Purple Rain,” has died. Blinn died Thursday of natural cases at an assisting living community in Burbank, California, his daughter, Anneliese Johnson, said Saturday. He won Emmy and Peabody honors for the 1971 TV movie “Brian's Song," which dramatized the friendship of Chicago Bears players Brian Piccolo and Gayle Sayers. Last month, Hall of Fame running back Sayers died at age 77. Blinn and Albert Magnoli wrote 1984′s “Purple Rain,” which Magnoli directed.