Today in Hollywood, taping begins on the first episode of a new situation comedy called "Diff'rent Strokes," about a lovable multi-millionaire who adopts two black kids from an urban ghetto. The show is produced by the Tandem Production Co. founded by Norman Lear, but that's not whose baby it really is.

It's the baby of a man who lives in meetings a few thousand miles to the East. When "Diff'rent Strokes" goes on the air the night of Nov. 3, it will be the first Fred Silverman show on NBC.

Until now, Silverman, who took over as NBC president and chief executive officer June 9, has only been able to affect the primetime schedule by toying with and relocating programs initiated under a previous regime. This era ends with "Diff'rent Strokes," which stars Conrad Bain and a 9-year-old find from Chicago named Gary Coleman - who was personally chosen by Silverman.

"I feel like I've been here a year already," says Silverman as he settles into a chair in his 6th floor Rockfeller Center office. "But I love it. It's an exhilarating job. The people who were already here and the people I've brought in make a marvelous team, and I think the morale is better here now than it is at either of the other two networks."

The day so far has been a typical one for Silverman, of whom a colleague says "dedicated" is really to mild a term. 'Obsessive' is more like it." The day began at 10 a.m. with a meeting on the reorganization of the NBC Radio network. As often happens, Silverman didn't interrupt it for lunch - he "sent out," and old habit from ABC days. The meeting ended at 5:30 and was followed by talks with Vice President Paul Klein, NBC News President Les Crystal and a meeting on "government relations," an area in which Silverman thinks himself not very proficient.

That's partly why Silverman chose another dynamo, Jane Cahill Pfeiffer, to be the new board chairman of NBC. She'll be responsible for "the whole Washington scene," he says.

Silverman, meanwhile, estimates he spends about 25 percent of his time on the TV network's prime-time schedule. "The Waverly Wonders," the Joe Namath comedy that has barely made a peep in the ratings, was canceled yesterday to make room for "Diff'rent Strokes," but he still holds out hope for the show that follows it, "Who's Watching the Kids?"

This platypus of a television program has been through more changes than Elizabeth Ashley already; now Silverman says the comedy series will be refocused away from the cutesy kiddies in the cast and toward the two zany bachelors next door, played by John Belushi's brother Jim and Larry Breeding.

"When those two guys are on the screen together, the show is funny," Silverman says. "What we have in mind is sort of the flip side of 'Laverne and Shirley.'"

A whole new season of pilot shows has been commissioned by NBC, and among those Silverman has high hopes for is "Mrs. Columbo." He's trying now to sign a certain top Hollywood actress to play the formerly unseen wife of Peter Falk's venerable Lt. Columbo, who would become the new unseen spouse on the new detective-comedy series.

Silverman has been criticized for moving "Quincy" out of its successful Friday night berth and into the network's weak Thursday lineup. Among the most vocal protesters over this heresy is the star of the show, Jack Klugman.

"He has calmed down," says Silverman with unmitigated finality. "'Quincy' is actually getting bigger audiences this year because there are more sets in use on Thursday night than on Friday night. The show will work where it is." On other fronts, Silverman thinks ABC's "Battlestar Galactica" will fizzle because "science fiction is a cult thing, and always has been on television," and says of ABC's "Taxi," a new hit comedy, "I wish we had it. But it wouldn't succeed on NBC right now because we don't have enough strong shows to support it; it's a special show, kind of delicate."

Meanwhile, it looks like curtains for old Grandpa on "Grandpa Goes to Washington," which hasn't been able to faze, much less threaten, the Silverman-engineered one-two of "Happy Days" and "laverne and Shirley." Perhaps nothing could.

"Never say 'nothing'," cautions Silverman. "'Happy Days' is one of those show that has been around a long time. It can't last much longer. Somebody is going to come along with an idea that will work."

Thus we have the new Silverman in head-to-head combat with the old. There are no signs the warrior is wearying. To the contrary. He sounds much bouncier now than he did last spring when Numero Uno ABC was celebrating its 25th anniversary with a series of shebangs on the West Coast, and Silverman, architect of the triumph, sat glumly at a party table and moped that his life was "boring".

"The thing about this business," Silverman says, "is that after you've done it, after you've become the leader, things get tenser. That's when it's really tense. The most fun I had at ABC was at the beginning, that first year, when everybody pitched in to make it work, and the ratings started getting better, and there was a wonderful atmosphere about it.

"Once you arrive at the point of leadership, you turn into a caretaker, a custodian. Then, if, God forbid, the ratings should slip a tenth of a point the guys in the sales department start screaming, and if the stock should fall a half a point, people downstairs start screaming.

"I think that in five or 10 years, the people who are at NBC now are going to look back on this period as the best time of their lives." The best time of his life, too? "I believe it will be."

Silverman began his NBC reign by calling for "programming that does not violate general standards of taste," which drew a few hoots from Hollywood where, it was alleged, the ABC-Silverman had ordered producers to put more sex and skin into their shows.

"That," says Silverman, barely raising his condensed-milk voice, "is a goddamned lie. Never in my life did I do anything like that. I know which producer started that story, and it simply isn't true."

Silverman tickled a few more eyebrows when he called upon advertisers and their agencies to increase their "participation" in a so-called "creative" decisions and program development at the networks. If there's anything television doesn't need, it is for sponsors to have more control over shows.

"I didn't say give them more control," says Silverman. "I said, increase the creative input. We need more ideas and more voices."

What about those horror stories from the '50s, of sponsors changing scripts so as to avoid controversy?

"For every horror story, there were probably 40 good things that were not horror stories. Remember in those days you had 'The U.S. Steel Hour,' you had 'The Philco Playhouse,' you had programs of that caliber."

Silverman's office is surprisingly simple and unpretentious - the usual executive plants, and a couch as paunchy as he is. True, there are three television sets hiding behind sliding electric doors that are opened from a button on his desk. And there is a handsome and impressive wooden console intercom with three phones and an uncountable number of push buttons.

"But this is nothing," Silverman says, demonstrating the sliding doors. "I remember the first time I was in [ABC president] Elton Rule's office, and he had a setup in there that looked like something out of "Flash Gordon." The doors clank shut.

The temptation is naturally to ask Silverman what makes him tick, but the answer is too obvious; he is a showman and a businessman of the old school, but with a new school sensibility. He is Louis B. Mayer scaled down and toned down for the cool age of television that he personifies and now dominates.

"I love planning things," he says. You can't tell.

It's been said Silverman can't have that much effect on the success of NBC prime time and the network generally until January or February. He says, "that will only be act one, scene one," but declines to spell out a timetable of progress, preferring a vague prediction of "some upward movement here," this season.

Although "Diff'rent Strokes" will be the first Fred Silverman show on NBC, has made his own network debut already, stalking out on the "Tonight" show to congratulate Johnny Carson on "15 fabulous years" with the network, even though Carson was celebrating 16 fabulous years.

Silverman was not thrilled with his own performance, but he was suffering from a cold and a still-lingering laryngitis (and he refuses to cut down on his huge daily intake of Salems).

The charming and revealing thing is that one of the most powerful men in American media was actually awed and intimidated by Johnny Carson.

"I felt very uncomfortable being there," Silverman says. "Going out there in front of that audience, and with Carson sitting there. We had this 40-pound trophy made for him, but I didn't want to get a hernia dragging that thing out there. I could barely get myself out there."

His turtle eyes survey the room, he adjusts his tie a la Rodney Dangerfield, and says, "Next year, I'll send somebody else."