The heart of rock 'n' roll? Simple. Kindly direct your attention to this map of Manhattan. Maybe it once was in the Delta or Motown or Liverpool, some place where people actually make music, but at the moment the heart of rock 'n' roll is right here, on the 18th floor of this undistinguished glass-box building on Sixth Avenue in midtown, with ancillary nodes here, at studios on West 57th Street, and here, at corporate offices in Rockefeller Center. It's MTV, Music Television, all day, all night, all stereo, all researched and packaged and formatted, all powerful and profitable and pervasive. And 4 years old today.

On Aug. 1, 1981, 100 MTV people had to trek across the bridge to a bar in Fort Lee, N.J. (since Manhattan's cable systems would not see fit to make the new network available to subscribers for more than a year), to watch the midnight launch. They heard a voice announce, ". . . five . . . four . . . three . . . two . . . one . . . Ladies and Gentlemen, Rock 'n' Roll." They saw the now-familiar rocket blastoff and man-on-the-moon animation (actual NASA footage tinted and tinkered with by the network's ace artists).

"Everyone was cheering wildly, like it was a space launch," remembers one who was there. " 'It's up! It's on! It's working!' "

This year's celebration will be more low-key: You don't need to make quite so much fuss when you reach 28 million households (local cable systems offering MTV include Tribune in Montgomery County, Metrovision and Storer in Prince Georges, Warner Amex in Reston, Media General in Fairfax, Metrocable in Arlington, Cable Communications in Loudoun County and Alexandria Cablevision), when your company netted $12 million last year, when you can plot your influence on records and radio, film and fashion, advertising, art and civilization as we know it.

Coming up in our story on MTV, gross-out at the Basement Tapes judging, JAP rap and Martha Quinn, just 15 minutes away. But first, let's go to the studio . . .

This is where the taping -- appearances to the contrary, virtually nothing on MTV is live -- goes on, in this leased studio space on West 57th. There's the set, which professional design consultants have carefully arranged to simulate random funkiness, the control room, the video jocks' dressing rooms, a few offices.

In the "veejay lounge," a combination library of rock encyclopedias and discographies and screening room, veejay Mark Goodman has one eye on a book and one on Sting's "If You Love Somebody Set Them Free."

Sting's video was directed by Kevin Godley and Lol Creme, who, at the moment, are shooting billiards in the Green Room, waiting to be interviewed by veejay J.J. Jackson. Godley, who's looking sleepy and fashionably unshaven, and Creme, who's perky and fashionably unshaven, will push their new album. "Here are some testimonials we'd like you to do," says the promotions man, handing Godley a script.

On the corner of the set that looks like a general store, with tin TruAde soda signs and a glass counter, the duo clowns with Jackson.

How did Godley and Creme meet? "I'd borrowed an 8-millimeter camera from a friend to do a remake of 'Dracula' and I was casting for a hunchback," Godley says gravely. What can viewers expect from the new album? "A headache, probably." Jackson says they'll be back after this word from Snickers. "Are they like knickers?" Creme wonders.

The exchange will be spliced into MTV programming over the next few weeks, and though Godley and Creme have other stops to make in New York, it's no accident that the PolyGram publicist brought them to MTV first. "It's very critical," she says. "For them. For anybody."

This interlude benefits all parties: PolyGram pushes its product, MTV maintains its hip aura by having musicians drop by, the promo people get stars to plug the upcoming MTV video awards show.

Videos, some have complained, are merely 3 1/2-minute commercials for record albums. "Of course they are," Senior Vice President for Programming Les Garland agrees jovially. "A live appearance by an artist is, too. That's the business we're in. If MTV can play a 3 1/2-minute clip that can take a record album from 1 to 3 million in sales, then we're in a healthy business."

When you factor in that what appears between the clips and interviews is either an ad (MTV generates greater ad revenues than any other cable network) or a plug for a concert tour or a promo for MTV itself, it becomes apparent that MTV is almost a 24-hour commercial. It manages to look and sound mildly subversive while simultaneously pulling in $46 million in revenues (including figures from its soporific sister network, VH-l, for grown-ups) for the first half of 1985. It gets some of the highest paid people in entertainment -- we're talking Peter Townshend, Keith Richard, Hall & Oates -- to look into cameras and say (for free) "I Want My MTV!" It's amazing.

Just ahead, MTV's chief operating officer and $450,000-a-year Wunderkind, 31-year-old Bob Pittman, tells how he put together the epitome of hip capitalism.

Pittman was a Warner Amex executive casting about for new ways to cash in on the supposed cable boom. "It was really time," he decided, "to marry music and television." He and a small team put together a business plan in November 1980; the Warner Amex board gave the go-ahead in January; MTV was on the air six months later.

Both music and television were "extraordinarily skeptical," Pittman recalls. " 'A harebrained scheme.' 'Watch music?' 'You don't do television that way.' 'We don't sell records that way.' Cable operators said their people would rather have country music."

It was Michael Jackson's "Thriller" video that galvanized the industry. The album had been riding the charts for a year, and no one thought there was another hit single in it, except Jackson and a few believers, including MTV. The network invested "a substantial amount" to produce the video. When "Thriller" made its MTV debut the album had slipped to a mere 200,000 sales a week; afterward it jumped to 750,000 copies a week and went on to sell another 10 million. MTV's unspecified investment "was never recouped," Pittman says, "but it was certainly worth it, the catalytic effect it had. It awakened the industry."

Sometime this month, MTV Networks Inc.(including VH-1 and the children's channel Nickelodeon) will learn who its parents will be. American Express wants to buy out its partner Warner Communications for $450 million, then sell Warner Amex Cable Communications to a joint venture of Time Inc. and Telecommunications Inc., the two largest cable companies. It's also possible that Warner will take on a new partner and buy out American Express. MTV executives say they're unworried. "It's a phenomenal success story," Les Garland observes. "I don't think anyone would mess with it very much."

Coming up in the next half-hour, the Brafman Tapes. But first, the Basement Tapes.

We're at a downtown video club called Private Eyes. Grim Reaper is late (it's a heavy metal band on RCA) but Fred Schneider of the B52s, Mick Fleetwood (as in Mac) and comedian Sandra Bernhard are here, along with various industry sorts, to judge the August Basement Tapes competition.

Despite its deserved image as a star maker (where would Duran Duran be without it?), MTV is useful only to bands that have already signed with record labels.

"One of the most important things we do is stimulate record sales," explains a spokeswoman. "When a tape comes in from a band that doesn't have any records, it doesn't make sense to play it because it doesn't help sales."

Once a month, however, MTV telecasts a good-will gesture: It picks six tapes, from 60 to 80 monthly submissions, and lets viewers call a 900 number to choose a winner. The victorious band gets a pile of recording equipment and a shot at an Elektra EP and a record company-produced video. And though none of the Basement Tapes winners is selling out Madison Square Garden yet, a few did get signed.

So the judges hunch dutifully over their voting forms. They watch women dancing provocatively around a band from Washington State called Strypes, and bombs falling in a black-and-white war staged by a Baton Rouge band called the Brink.

"I haven't liked any of 'em so far," snarls Bernhard. "Naked women and guns." En route to the club, Bernhard and her manager learned that the Jonathan Demme-directed video from her first album was rejected by MTV, as are roughly a quarter of the videos submitted. Bernhard is ticked off -- she leaves before the judging's over -- but she's not so ticked that she won't first perch on a stool for an interview with veejay Martha Quinn. MTV can say no to you but, if you're interested in selling records, you don't say no to MTV.

The clip that makes everyone put down the crudite's and listen up, from a Chicago group called Heat and Serve, is titled "Rats on a Budget, Part II." It depicts a happy picnic where a chef grills patties with feet and long tails. Boogieing waitresses sing the title song while customers feast on plain rats, rat sandwiches, rats with condiments.

Fleetwood chuckles; Schneider looks pained. "I didn't like it when they poured catsup and mustard on a rat," he says afterward. "I'm a vegetarian."

"Rats on a Budget" will appear on the Aug. 11 show nonetheless. Its competitors include a clip from Mark Gamma and the Nasty Habits and something called "Surfin' Girl" by the Slammin' Romance.

We'll be hearing from a conceptual artist who sculpts manatees . . . and Martha Quinn will share some of her favorite rock trivia. First, though, back to the l8th floor . . .

You can be forgiven for thinking that MTV is the product of a mellow bunch of guys and gals who, like, just wanna groove to the music, who are, y'know, more hip than capitalist. Most of the people coming and going here wear pointy shoes and pushed-up jacket sleeves and talk about the Live Aid concert, which MTV telecast all 17 hours of, as the most incredible, unbelievable, goose bump-inducing event of their lives.

Even The Suits, the veeps who do not come to work in pointy shoes or pushed-up jacket sleeves, are cool. None of them is over 40. John Sykes, vice president of programming, was out club-hopping till 4 a.m. with David Lee Roth last night. Sykes, who's 30, was chugging club soda because he had an 8 a.m. meeting, which tells you something about how loose MTV really is. Still, he will stop in mid-interview to point to the TV monitor across the office (The Suits watch MTV all day long) and yelp, "There's Wembley! That's where I was last Saturday. U2 was incredible! Turn the sound up, will you?"

And how many corporate executives would spend time listening to an audio tape called "JAP Rap?" A job applicant left it with Kevin Metheny, 31, vice president in charge of music and production. A nasal New York female voice intones, "I hate to cook, I love to shop; my hands have never touched a mop."

But however wild and crazy it appears, MTV is a highly controlled business. Metheny, for instance, is superintendent of cool appearances. That swell set, where Mark Goodman can sprawl in a brocade armchair that's losing its stuffing -- it looks like a Cambridge crash pad but it's the work of design consultant David Morong. The luncheonette set, with its leatherette booth and Seeburg jukebox, is "a modular interview situation," Metheny says. Its parts knock down for better camera access and it's equipped with seat cushions of varying heights, "so Martha Quinn doesn't look like a dwarf when she's interviewing Mark Knopfler."

How Quinn or any of the veejays looks is also no accident. Stylist Sydney Kai Inis often goes shopping at Charivari with Jackson and to the vintage boutiques in the Village where Quinn stocks up on Hawaiian prints. One of the reasons that MTV refuses to license articles of clothing is that they'll go out of style. "We don't want someone out there wearing an uncool garment 48 months from now," Metheny says.

One of the very coolest things about MTV is its visual punch, powered not only by the videos themselves but by a collection of logos and promos and animations shepherded by Marcy Brafman, director of on-air promotions. The spots have won three Clios and a slew of other awards.

The Brafman Tapes show the signature rocket blastoff, which Brafman stops in midlift to explain that this is "a representation of exploration and a pioneering spirit," which seemed appropriate four years ago when a video music channel was an alien notion. And it shows MTV's logo, changing from plaid to spots to stripes. "The dominant rule about logos is, they're always the same," Brafman lectures. "We said, 'Let's do the opposite.' It represents a philosophy of rock 'n' roll, youth, rebellion."

Brafman's reels use lots of the black-and-white archival footage with incongruous narration that MTV loves: Army film of cows saying they wanna hear rock 'n' roll mooosic; a volcano spewing while an announcer booms, "Another contest erupts."

The Devo Hawaiian Holiday was, Brafman continues, "the beginning of our strange contest spots. We used to show nice people going glamorous places. Then we said, 'Naaa.' " This one features tourist footage while a voice caws, "Aloha, beautiful mutants." Some of MTV's strange contests have been spectacularly successful: the network received more than 1 million post cards from viewers hot to spend a Lost Weekend With Van Halen.

There's more. Brafman unreels a spot called the Diamond and the Egg -- "It's the hardest substance known to man, but you can't watch Boy George on it."

Just five minutes away, the manatee man meets the veejays.

A ceremony is about to take place on the "Archie" set, which contains the Bunkerish armchair. A conceptual artist named Tiite, whose previous claim to fame was a sculpture of two manatees erected in a river near Fort Myers, Fla., was so inspired by MTV's Live Aid coverage that he put together a copper and canvas art work.. The next time there's a war, Tiite explains, world youth will simply say, "Hey, Jack, I can't go kill someone I've been to a concert with."

(MTV people think it took a bum rap from critics charging self-promotion during Live Aid. The frequent cutaways to bopping veejays and crowds covered technical snafus and empty stages, Pittman says. He points out that while ABC and independent stations made money on their broadcasts, MTV donated 100 percent of its revenue. "Everyone else was dealing with commerce; we were dealing with the cause," he says.)

Tiite, Metheny and veejays Quinn, Jackson, Goodman and Nina Blackwood (only Alan Hunter -- picture John Boy in a pricey haircut -- is missing) run through the presentation twice; it will probably wind up on Music News.

Tiite seems as excited about being on MTV as he is about world unity. His son snaps photos of him embracing Quinn and Blackwood, MTV's perky sprite and sultry mama, respectively. "You'll never believe how many people love you out there," Tiite burbles.

J.J. Jackson recently returned from hosting a Tubes concert in Puerto Rico. "I walked in and you'd think Elvis Presley had landed," he reports.

After 14 years in FM radio, Jackson has a certain perspective. He's famous, "but Francis Ford Coppola hasn't called yet." He's proud of MTV but likes to quote Jefferson Airplane to the effect that fame doesn't mean much to a tree.

It does, on the other hand, mean a fair amount to the relentlessly effervescent Martha Quinn, hired right out of NYU. Quinn was days away from becoming the weekend deejay at a "beautiful music" station when she dropped in to see friends at WNBC radio. One of them called Pittman and arranged an audition.

"He could see me in 20 minutes," exclaims Quinn, clearing piles of dirty clothes off a chair in her dressing room. "I had to borrow money for the cab. I was wearing this iron-on sparkly shirt, 'Country Music Is in My Blood.' I think I'm gonna frame that shirt!"

Of the thousand or so letters the veejays receive weekly, Quinn gets more than her colleagues because (she says) of the volume of trivia questions viewers submit for her nightly contest. Quinn researches these items diligently. "My latest triumph is," she shouts suddenly, "Peter Frampton called me! I called his manager and asked was it true Peter used to be in a band called the Preachers that Bill Wyman managed. And I also found out his father used to teach David Bowie art in high school! Can you believe this?

"And Adam Ant's mother used to be whose housekeeper? C'mon, guess. No, c'mon. It's Paul!" McCartney, she means. "I've even spoken to John Oates' wrestling coach. Isn't that funny? I love that stuff!"

During a discussion of fashion finds, Quinn suddenly realizes something about the Hawaiian skirt she's wearing. "I've had this since . . . you wanna know something? This is the skirt I was wearing when I beeped my answering machine and learned that I got the job! I think I'll frame this skirt!"

Up next, some industry people talk about life post-MTV.

It changed everything. The record industry was in a serious slump in 1981 and people in it think MTV (along with the economic recovery) helped pull it out. "MTV's impact has been palpable and documentable," says Len Epand, PolyGram's senior vice president and general video manager. "Def Leppard went from being a bubbling-under, not-even-gold act to selling seven million units of Pyromania. There was nothing happening; then MTV started playing the video from their second album."

Record companies meet or talk with MTV executives weekly, pitching videos. They will cut and reedit if MTV finds something (from nudity to heavy-metal S&M to an identifiable can of Tab) offensive.

Psyching out what MTV wants has become a popular guessing game. "To be a record company and not have a good relationship with MTV would be a real problem," says Laura Foti, director of marketing for RCA video programs.

The network has moved to consolidate its power over the past year. It -- and all the other video music outlets, from syndicated shows to network programs -- used to get videos free. The record companies picked up the production tab, which can run up to $150,000. But last year, MTV began signing three-year deals with the leading labels, paying yearly fees for videos but commanding the right to show them exclusively for 30 days or more. None of the labels declined, though neither they nor MTV will discuss the terms of the agreements. But with labels beginning to charge other outlets, too, some of them may go under.

Meanwhile, MTV is trying to keep a competing New York video-playing UHF station off local cable systems, via an FCC petition. A recent U.S. Court of Appeals decision on FCC "must carry" rules will help. It gets harder to see who could mount a serious competitive challenge to MTV, or how.

The intriguing thing is how far and fast MTV's influence has spread. To fashion, for instance. People in Birmingham and Harrisburg knew it was cool to wear Hawaiian shirts this summer because veejays wore them last spring. MTV showed kids knew how to dress for Madonna concerts. Trends always traveled, but not with such startling speed.

Film studios make soundtrack videos to help promote their movies. Commercials borrow MTV's color and pacing and music: At times it is tricky to distinguish MTV's video clips from the Levi's and Pepsi ads surrounding them.

In fact, MTV will happily take credit for almost anything that emphasizes mood, style and sensation over narrative, including movies like "Flashdance" and "Footloose." "We are flattered," Metheny says, "by 'Miami Vice.' "

All of which leads to certain chilling images. MTV is already seen, in truncated fashion, in Japan and Mexico, and negotiations with other foreign broadcasters are under way. Will foreign correspondents begin noticing Koreans with Mohawks? Will there be demonstrations in Romania of kids chanting, "I Want My MTV"? Will Fidel be dropping by the set to chat with Mark Goodman about how cool socialist revolution can really be (all those funky camouflage shirts)? A worldwide reach for MTV could be the most revolutionary, or the most narcotizing, development of the atomic age. "We are looking," says Pittman, and he says it with utter seriousness, "at the world."