To be young, cute, not all that bright, and living in Southern California. It's an American dream, one very beguilingly reflected in "Fast Times," a new CBS comedy series based on the book and movie "Fast Times at Ridgemont High" and premiering at 8 tonight on Channel 9.

Most people who watch the program will find themselves charmed and amused. But for Allen Rucker, it will be a nail-biter all the way. Although he has been working in and around television for 15 years or so, "Fast Times" marks the first show Rucker has produced for network prime time that got beyond the pilot stage. It is his first real chance at a big, sloppy hit.

"It feels right. It's solid. It could bust through in the ratings!" Rucker exclaimed over lunch recently in an appropriately frantic Hollywood restaurant.

"You know, it's very exciting, this prime-time television business."

Exciting, yes, and maddening, this prime-time television business, and for Rucker, whose TV roots include work with the pioneering video group "TVTV" and a stint as producer of "SCTV Comedy Network," network prime time means a new set of frustrations and a new set of compromises. One compromise that had to be made right off the bat was that "Fast Times" as a TV show could not contain anything resembling the drug jokes and R-rated sex comedy of the film.

Thus a daffy high school student named Spicoli, who as played by Sean Penn in the 1982 movie was in a state of perpetual marijuana-induced befuddlement, is now in a state of perpetual organic befuddlement. He is just a fellow with an exaggerated sense of the funness of life. He makes no references to drugs.

Spicoli is played in the series by a convincingly spacey young actor named Dean Cameron, who looks a tad too old for the role but makes it work anyway. The cast is one of the most instantly ingratiating in situation comedy history. That includes teachers as well as students: Ray Walston, the unflappable pro, returning in the role he played in the film, a history teacher named Mr. Hand -- he's Spicoli's nemesis, and vice versa. Vincent Schiavelli revives his film role as Mr. Vargas, a science teacher who takes his mandate to entertain as seriously as Liberace takes his.

The role of a third teacher -- Ms. Melon, instructor in the elusive subject of "life studies" -- has been added for the TV series and is played by Kit McDonough, who has the breezy, bounced-off-the-wall delivery of a mature Teri Garr.

Among the students are Patrick Dempsey as Damone, hustler of Tears for Fears concert tickets and noted sleaze about school; Claudia Wells as Linda, who believes in life, liberty and the pursuit of boys; the immaculately adorable Courtney Thorne-Smith as Stacy, the school's "white bread princess" and a scholar of the more practical verities; and Wally Ward as Ratner, the quintessential Everykid, a glutinous mass of tortured self-doubts and insatiable personal anxieties.

Moon Zappa, an actual American teen-ager, not only plays Barbara on the show but also serves as "technical adviser." The title tune, to drop a name that bounces, is by Oingo Boingo.

On the premiere, Ratner decides Stacy is the answer to his every furtive prayer. "Her hair is like gold, her eyes are like blue, and her body's my exact perfect favorite kind," he tells Damone, who volunteers to get the ball rolling with Stacy and then hand her off like a prize to the shy Ratner. Things don't work out, much as you would expect them not to work out, except that the story is resolved with fresh finesse.

A subplot has Spicoli vowing to make stern Mr. Hand laugh during class, a mission deftly resolved in the script by Marc Warren and Dennis Rinsler. The "Fast Times" premiere was directed by Amy Heckerling, who directed the original movie and who, if anything, has grown sharper and subtler in the intervening years.

None of the action on the premiere takes place in anyone's home; typically of the series, everything happens either at school or at the mall. The mall, Rucker said, functions as "the Arnold's of the '80s," a reference to the teen-age hangout in "Happy Days," which is a program Rucker has no desire to emulate. Although he wouldn't kick its ratings out of bed.

Rucker is giddy with pride over the fact that "Fast Times" has turned out pretty well; indeed, it is a happy, sweet surprise, much more humane than almost any of the teen-age comedies that have broken out like acne on the movie screens of the nation during what seems like an interminable cinematic puberty.

What impresses Rucker, he said, is how little grief he got from the network in the course of this experience, at least as compared with what he was expecting. The network ordered a pilot and six episodes after seeing only two days' worth of rushes from the first episode. The network even let Rucker have his way and produce the show without a laugh track, almost unheard of for a half-hour comedy.

"The progress of this show vis-a -vis the network has been one of those things where any moment you expect the other shoe to drop," Rucker said. "It can't be this easy; you know, they can't approve writers like this, their comments on scripts can't be this benign. They can't be so out of it. Weeks go by and I don't even talk to them."

He thinks CBS may in part have learned a lesson from another network. "NBC has thrown a long shadow in the way they've operated with creative people, the way they let them go off and do what they want and trust their judgment." A previous network pilot he produced, "Gossip," in 1979, was precisely the opposite experience, Rucker said. "Insane. Completely out of control."

Even the censor has been rather accommodating. Originally CBS wanted the word "frigid," which it considered too suggestive for an 8 o'clock show, removed from tonight's premiere, but it has remained. Earlier, Damone tells Ratner that if Stacy were to say she'd had a dream about him, his response to that should be, "How was I?" The network censor ruled this "too sexually direct." But on appeal, the line stayed in.

A much larger problem for Rucker is ratings pressure. "Fast Times" has only six weeks to snare an audience. Complicating this is the fact that CBS tends to attract older and more rural audiences in prime time, not exactly the target group for a hip comedy about a contemporary high school.

"We're doing an NBC show on CBS," Rucker said worriedly. "I didn't realize how dowdy the network is that we're being programmed for. There are no shows on CBS that feature kids. 'Kate & Allie' is the closest show on the network with the same general appeal."

The stifling fuddy-duddiness of CBS, which has been bested in the ratings this year by the more youthful NBC, could be devastating to the fate of "Fast Times."

But Rucker is determined to mine the experience for all its worth, whether the show succeeds or not. His arrival into the arena of the big buck hasn't dampened his enthusiasm for television or for theorizing about it.

"Most television shows are their own reality, and they win over an audience when the audience comes to accept that reality," he said. "It has nothing to do with any other reality. 'The A-Team' has its reality, 'Punky Brewster' has its reality, 'Silver Spoons' has its reality. But some television shows at least walk the kind of line that we're walking, the line between comedy and authenticity."

Thus high school age viewers, and those for whom high school is a distant memory, may not feel "Fast Times" is shatteringly true to life, but they may see enough familiar and truthful in it that they can connect to it. "People are going to have to watch this show because they like the characters," Rucker said.

The show's teen-age slang may not be up-to-the-minute, but it does seem credibly colorful. What one wants to be perceived as in this lexicon is "radical," as opposed to, unthinkably, "a complete wiener." On the second show of the series, Spicoli uses the evocative adjectival hybrid "boocoo hot" to express approval. What Rucker and his colleagues have produced in "Fast Times" is a television program that is boocoo good.