'The Purest Street Awareness'

''The basis of this show is fish out of water,'' said the executive producer, Quincy Jones, the music impresario who has never before put his name on a television series but whose work as producer of Michael Jackson's albums won him respect in Hollywood as a canny judge of public tastes. ''Rap is not the primary focus. If you took the rap out, the premise wouldn't fall apart. But rap gives you the purest street awareness.''

Just how much of rap culture should be grafted onto the comedic is a problem the producers, writers and actors of ''Fresh Prince'' are still trying to solve. Their efforts ever since the head of NBC Entertainment, Brandon Tartikoff, approved the project in April have been aimed at finding a tone that preserves the grittiness of hip-hop without alienating a mass audience expecting laughs.

''When we handed in the first draft of the script, the network freaked out,'' said Susan Borowitz, a veteran of ''Family Ties'' who wrote the pilot episode with her husband, Andy, and produces the show with him. ''They were expecting 'Crocodile Dundee' and 'Beverly Hills Cop' and were quite taken aback by the Malcolm X poster'' that Mr. Smith's character hangs in his bedroom.

The primary focus of the series is not tension between blacks and whites, but the cultural differences and misunderstandings that separate Fresh Prince and the black bourgeoisie, represented by his relatives. Imagine the domestic bliss of the Huxtable family on ''The Cosby Show'' interrupted by a good-natured but coarse and noisy intruder from the streets, and you have ''Fresh Prince'' in a nutshell.

Characters Over Concept

''The concept of this show has been described as slender and slight, and that's true,'' said Mr. Borowitz, who worked at the ''Harvard Lampoon'' with his wife before going on to write for ''Archie Bunker's Place.''. ''This a vehicle to bring the hip-hop sensibility and Will Smith to television. The characters and the actors are more important'' than the concept.