TV RATINGS

Bill Cosby regained his No. 1 spot from “Family Ties,” NBC won the week and embattled CBS won the news in the prime-time ratings released Tuesday by the A.C. Nielsen Co. “The Cosby Show,” which lost to “Family Ties” a week ago for only the third time since the two shows became Thursday night hits, was again in the top position. “Family Ties” was second, followed by “Cheers” and the movie-pilot premiere of the new NBC series “Rags to Riches.” “Rags” aired twice during the week, and was listed in 18th place for its regular hourlong Sunday night time slot. For the week, NBC had an 18.2 rating and 28 share, CBS a 15.1 rating and 24 share, and ABC a 13.4 rating and 21 share. NBC has won 22 times during the 25-week-old season. On the news front, Dan Rather on CBS earned a 13.0 rating and 23 share, Tom Brokaw on NBC had a 12.0 rating and 22 share, and Peter Jennings on ABC a 10.7 rating and 19 share. The full ratings list appears on Page 9.