NEW YORK (AP) _ Here are the prime-time television ratings as compiled by the A.C. Nielsen Co. for the week of October 26-November 1. Top 20 listings include the week's ranking, with full season-to-date ranking in parentheses, rating for the week, and total homes.

An ''X'' in parentheses denotes one-time-only presentation. Shows from 21 on include only the weekly ranking. A rating measures the percentage of the nation's 88.6 million TV homes.

1. (1) ''The Cosby Show,'' NBC, 31.3 rating, 27.7 million homes.

2. (2) ''A Different World,'' NBC, 27.7, 24.5 million homes.

3. (3) ''Cheers,'' NBC, 26.8, 23.7 million homes.

4. (4) ''Growing Pains,'' ABC, 25.7, 22.8 million homes.

5. (5) ''Night Court,'' NBC, 25.0, 22.2 million homes.

6. (6) ''Who's the Boss?'', ABC, 23.7, 21.0 million homes.

7. (9) ''Murder, She Wrote,'' CBS, 21.9, 19.4 million homes.

8. (10) ''60 Minutes,'' CBS, 21.7, 19.2 million homes.

9. (12) ''L.A. Law,'' NBC, 21.0, 18.6 million homes.

9. (11) ''Family Ties,'' NBC, 21.0, 18.6 million homes.

11. (25) ''Echos in the Darkness,'' Part 1, - ''CBS Sunday Movie,'' 20.1, 17.8 million homes.

12. (8) ''Moonlighting,'' ABC, 19.3, 17.1 million homes.

13. (7) ''Golden Girls,'' NBC, 18.9, 16.7 million homes.

14. (13) ''ALF,'' NBC, 18.5, 16.4 million homes.

15. (14) ''Newhart,'' CBS, 18.3, 16.2 million homes.

15. (29) ''Kate & Allie,'' CBS, 18.3, 16.2 million homes.

17. (14) ''My Two Dads,'' NBC, 18.0, 15.9 million homes.

18. (22) ''Matlock,'' NBC, 17.9, 15.8 million homes.

19. (16) ''Dallas,'' CBS, 16.9, 15.0 million homes.

20. (27) ''Designing Women,'' CBS, 16.6, 14.7 million homes.

21. (19) ''Dangerous Affection'' - ''NBC Sunday Night Movie,'' 16.4.

22. (30) ''NFL Monday Night Football: L.A. Rams vs. Cleveland,'' ABC, 16.3.

23. (25) ''Hunter,'' NBC, 16.0.

24. (16) ''Amen,'' NBC, 15.9.

25. (19) ''Deep Dark Secrets'' - ''NBC Monday Night Movies,'' 15.5.

26. (32) ''Falcon Crest,'' CBS, 15.1.

27. (33) ''thirtysomething,'' ABC, 14.9.

28. (35) ''Knots Landing,'' CBS, 14.8.

29. (X) ''CBS NFL Football (overrun),'' CBS, 14.7.

30. (51) ''Our House,'' NBC, 14.5.

31. (39) ''Cagney & Lacey,'' CBS, 14.1.

32. (37) ''Miami Vice,'' NBC, 13.9.

33. (33) ''Dynasty,'' ABC, 13.8.

33. (24) ''Head of the Class,'' ABC, 13.8.

35. (47) ''MacGyver,'' ABC, 13.7.

36. (31) ''Perfect Strangers,'' ABC, 13.6.

37. (X) ''Mama's Boy,'' NBC, 13.4.

37. (46) ''St. Elsewhere,'' NBC, 13.4.

37. (42) ''The Equalizer,'' CBS, 13.4.

40. (28) ''227,'' NBC, 13.3.

40. (43) ''Beauty and the Beast,'' CBS, 13.3.

40. (44) ''Frank's Place,'' CBS, 13.3.

43. (22) ''Hooperman,'' ABC, 12.8.

44. (49) ''20-20,'' ABC, 12.6.

44. (19) ''Dolly 3/8'' ABC, 12.6.

46. (45) ''J.J. Starbuck,'' NBC, 12.3.

47. (49) ''Jake and The Fatman,'' CBS, 12.2.

48. (48) ''Crime Story,'' NBC, 12.0.

48. (41) ''Highway to Heaven,'' NBC, 12.0.

50. (53) ''Mr. Belvedere,'' ABC, 11.9.

51. (63) ''Tightrope'' - ''ABC Thursday Night Movie,'' 11.6.

52. (36) ''Magnum, P.I.,'' CBS, 11.5.

52. (X) ''Storyteller: Fearnot,'' NBC, 11.5.

54. (63) ''I Married Dora,'' ABC, 11.1.

55. (61) ''Tour of Duty,'' CBS, 10.8.

56. (57) ''The Return of the Shaggy Dog,'' Part 1, - ''Disney Sunday Movie,'' ABC, 10.7.

56. (53) ''Wiseguy,'' CBS, 10.7.

58. (67) ''Full House,'' ABC, 10.6.

58. (X) ''Disney Special: DTV Monster Hits,'' NBC, 10.6.

60. (63) ''The Pursuit of Happiness,'' ABC, 10.5.

60. (38) ''The Slap Maxwell Story,'' ABC, 10.5.

62. (X) ''Harry Anderson Special: Sideshow,'' NBC, 10.2.

62. (61) ''Spenser: For Hire,'' ABC, 10.2.

64. (56) ''The Law and Harry MacGraw,'' CBS, 10.1.

65. (51) ''Buck James,'' ABC, 9.4.

66. (55) ''A Year in the Life,'' NBC, 8.9.

67. (59) ''The Oldest Rookie,'' CBS, 8.8.

68. (X) ''Top Flight,'' CBS, 8.6.

69. (68) ''Hotel,'' ABC, 8.4.

70. (71) ''Sledge Hammer 3/8'' ABC, 7.9.

71. (70) ''The Charmings,'' ABC, 7.8.

72. (73) ''West 57th,'' CBS, 7.5

73. (72) ''My Sister Sam,'' CBS, 6.5.

74. (X) ''The Midnight Hour'' - ''ABC Movie Special,'' 6.3.

75. (73) ''Everything's Relative,'' CBS, 5.6.

76. (76) ''Leg Work,'' CBS, 5.2.