THE NBA: a $400,000 fantasyland, where a backup point guard earns more than upper-midlevel corporate management. Where the size of the restaurant tab is irrelevant. Just sign the credit card receipt and call your agent at the end of the month.

The NBA: home of the foot-long plane ticket and the Holiday Inn. Where you check the matchbooks in your jacket pocket to see where you were last week.

The NBA: land of the loose-ball foul, Brent Musberger and unbreakable glass backboards. A 902-game method of sifting out the best 12 teams from the other 10 and affixing a site for the finale of any playoff series that should happen to go seven games.

Recently, a man who grew up as an old-line NBA fan in Boston in the late '50s and early '60s (there was no better place or time to become one) set out from Washington on a 10-day, five-game, five-city, NBA odyssey. Game One Philadelphia, Dec. 12

The ride to Philadelphia is always pleasant, if you plan it in the daytime. That way you can pick up the solid gold soul on WSID in Baltimore right from the get-go and carry it with you all the way to the toll booth on the Maryland Turnpike, on the other side of the Susquehanna River Bridge.

By this time, you are less than 60 miles from the City of Brotherly Love and nearly in range of radio 95, WPEN, with its "Great Stars and Great Music." Usually good for at least one Sinatra selection per hour.

The Spectrum is located at the southern edge of South Philadelphia, one of America's great neighborhoods. An early arrival allows time for two pregame necessities. I pick up a Philadelphia Daily News and then drive a few blocks past the Spectrum up Broad Street and turn left on Shunk Avenue to the Rosewood Bar.

The Rosewood is the archetypal South Philly tavern: small, cozy and friendly. I put $2 on the bar to pay for a screwdriver and a draft beer. Only one bill is taken. Twenty cents is returned.

At first glance, tonight's 76er game against the Milwaukee Bucks appears attractive, a battle of division leaders. The Sixers are tied with Boston in the Atlantic Division; Milwaukee leads the Midwest with a 20-13 mark.

Not many Philadelphians, however, seem enamored of this matchup. Only 10,000 show up. Sportswise, as always, they are correct. The Bucks have built their division lead with a 10-1 start. For the last month, they have been strictly mediocre.

It is not hard to ascertain why. Their inside presence is about as commanding as a lone foot patrolman in a riot. Against Kent Benson and Richard Washington in the middle, the 76ers have little need for anything but layups.

These include a series of slam-jams and tomahawk stuffs by the medical staff, Doctor J (Julius Erving) and Doctor Dunk (Darryl Dawkins), and are enough to keep most of the fans entertained for three quarters.

However, with the home team up by 30, a full period of patented NBA garbage time looms. The thousands that begin their early exit are deprived of seeing Jim Spanarkel cop the evening's Golden Trash Can Award with 10 fourth-quarter points.

The most anticipated subplot of the night is Dawkins' versus the backboards. After the previous week's great shattering, the crowd is assembled to see if Dr. D can break through the second week in a row, Commissioner O'Brien notwithstanding.

But tonight's round goes to the fiberglass.

In the locker room, bedecked with three golden necklaces, one engraved "Dr. Dunk," the Chocolate Thunder is asked about his new policy of backboard detente.

"I don't dunk any more, man. I just glide with ease."

Could any of this have to do with his recent conversation with the commissioner?

"That doesn't matter. I'm into finesse now. There's more style that way."

Before leaving, reporters are reminded that Dawkins will be at the Cherry Hill Club the next evening to spin six hours of disco. Julius Erving will be there and Donna Summer and Teddy Pendergast records will be featured. Game Two Piscataway, N.J., Dec. 14

There is only one must on the short five-mile hop to Piscataway. That is the Richard Stockton Service Area on the New Jersey Turnpike. This is the only rest stop on the turnpike at which you can pick up all seven papers from Philly and New York, as well as the Newark Star-Ledger and the Trenton Times.

After garnering my full measure of pregame reading material, I'm ready for the NBA's only local rivalry: the New Jersey Nets vs. the New York Knicks.

Someday this will be the league's showcase. The Nets will get back Julius Erving; Bill Cartwright will become a Knick superstar, both teams will be vying for the division lead, and scalpers at the Meadowlands will charge $100 a pair.

Right now, however, completion of the Meadowlands facility is a year away, both teams are going nowhere, and the Rutgers gym, the Nets' temporary home, is still 40 miles south of the Hudson River.

The gym (capacity approximately 9,000) is said to be on the Rutgers campus, but the only building anywhere nearby is a library, which sets the appropriate tone for this evening's audience.

The Nets enjoy a comfortable margin most of the evening, the Knicks close to six in the last quarter, then the Nets pull away to win by a dozen. The fans go away happy, but one senses none of the special satisfaction that should go with the beating of a hated local rival.

The game confirms several prior suspicions: Net center George Johnson, perennial league leader in both blocked shots and disqualifications, still slaps at everything as if it where the opening tap. Knick guard Ray Williams has the shot selection of a drunken rifleman. Mike Newlin, New guard, plays every game as if he were in tryout camp.

Other random impressions from the Nets are: that Eddie Jordan is quick and effective in a running game, that Jan Van Breda Kolff is one of the most underrated players in the league, especially defensively, and that Calvin Natt should be a can't-miss superstar.

On the Knicks: Larry Demic works hard at defensive forward, and with his shooting he'll have to if he wants to stay on the team. M. R. Richardson has extremely quick hands, but that's no revelation since he leads the league in steals. Cartwright is an awesome inside force on offense and incredibly more aggressive as a rebounder than he was the four times I saw him play for the University of San Francisco.

Newlin has been one of the prime beneficiaries of the new NBA three-point rule. He explains after the game, "I just seem to feel the shot. I like to do it for momentum. It picks up the crowd like a dunk. Maybe even more so."

I wonder aloud how as great a player as Calvin Natt could go unnoticed in high school and wind up at an obscure place like Northeast Louisiana.

"Oh, I could have gone anywhere I wanted," he said.

"It sure looks that way," said one listener. Natt smiles.

"My home town of Bastrop is only 19 miles from Monroe. I used to go to Northest every summer for clinics. I always liked the school and the coaches. It's a nice place and has a big lake around it." Game Three New York, Dec. 15

I'm looking for the excitement level on this trip to pick up tonight for two reasons. One is that this is Walt Frazier Night and Madison Square Garden has been sold out for a month. Two is that the opponent is the Boston Celtics, who, with the 76ers' loss to Atlanta the previous night, now have the best record in the league.

One is quickly caught up in the sheer outpouring of emotion at the Garden. The City Game has not belonged to the city for more than five years now, and on this night the men who brought it here have all come back. Everyone from Willis Reed and Dave DeBusschere to Nate Bowman.

The roll is called and they come out one by one and line up on either side of center court. Cazzie Russell, in his gray suit, stands next to the Pearl, Earl Monroe, in warmups. Monroe is the last Knick still active from the glory days of '69-'73. DeBusschere and Reed enter to standing ovations.

And now, Clyde.

As ever, he is the fashion plate, with a gray pinstripe suit, black shirt, white tie and white shoes.

A space is left between the two lines of Knicks. Not too wide, but wide enough. For Clyde has always been one to keep his distance. Cool and alone.

On the message board between the Burger King and Eastern Airlines emblems, the lights flash out, "Welcome Home Clyde #10 #10."

The thunderous chant reverberates once more from the crowd, "DEE-FENSE, DEE-FENCE," and the awards are presented.

First is a scrapbook, presented by a 10-year-old. Then a silver plate from Coach Red Holzman. Finally, to the loudest cheer of the evening, the presentation by Reed of the No. 10 jersey, which will be retired and hung from the Garden rafters next to his own No. 19. They are the only Knicks so honored. The club had not intended to retire Frazier's jersey in this ceremony.

Under intense pressure from the fans and the media, led by a full page of commentary in the New York Post, management caved in.

What is so refreshing about Frazier's speech is that it is devoid of the syrupy humility that seems almost obligatory on these occasions.

Clyde thanks the Knicks management "for knowing a talent when they see one," and his teammates -- "Without them, I'm sure I would have been good, but with them, I was great."

After thanking the fans for being "the greatest in the world," he leaves shaking hands up and down the lines to the organ accompaniment of "For He's a Jolly Good Fellow."

Must we really go through with the game?

It says so on the schedule, so we go through four quarters of closely contested but not overly exciting basketball.

This game is on a higher level than my last two encounters, for there is an urgency about the Celtics that sets them apart from most of their colleagues, even if the execution isn't always there to match it. Tonight, it isn't.

The Knicks, before the packed house, also show a concern for the outcome. Without much perimeter shooting, their offense, outside of Cartwright, is not particularly overwhelming.

Yet with 30 seconds to go, owning a 96-95 lead and the ball, the Knicks look about ready to put this one in the can.

Is is at about this time that a new NBA axiom that is rapidly gaining popularity among Knick opponents begins to apply: "Just stay close for 47 and let Ray have it."

First, the unfortunate Williams is trapped in the corner of the inbounds play by Chris Ford and M. L. Carr. This results in a wide-open Celtic layin for Don Chaney.

On the next Knick possession, Williams manages to double-dribble away from pressure undetected but then, as usual, he commits too early and throws the ball away.

As he explained afterwards, "I was looking for someone up there with me but all I saw was Cartwright and he was surrounded by three green jerseys."

One of them, Chaney, picks off the ball and lays it in.

Boston 99, New York 96.

The organist sends everyone home with "Ain't Misbehavin.'" Game Four Boston, Dec. 19

Videotape cartridge for every fan. That is what CBS should make of the first half here and arrange for tape-player manufacturers to give away with each purchase, it they really want to promote the NBA.

This game between the Celtics and Philadelphia figures to be special since the teams are sporting the league's two best records coming in. But it is not the competition that makes it memorable.

It's been a long time since there has been a finer night to be a Celtic fan. The Celtic 112-89 blowout of the 76ers goes beyond a game. It becomes pure, unadulterated theater, with Larry Bird and Nate Archibald the costars and Cornbread Maxwell the supporting actor.

Maxwell is on the receiving end of some of the greatest sleight of hand this side of a magic show. Among the acrobatic fast-break passes of Bird and Archibald that he receives throughout the second quarter, surely must be an NBA record: two blind-flip assists in two minutes.

I'm seated at the press table, next to Don Gillis, a man known for his low-key professionalism throughout a distinguished 25-year career as a Boston sports anchor man. By the end of the half, Gillis is hugging me.

In a year when many teams around the league are suffering at the gate, this is the Celtics' 18th sellout -- home and away.

The heading catalyst in the transformation from last year's 29-53 team is rookie 6-9 forward Bird. All his superstar skills -- the prerequisites of scoring and rebounding, the point-guard passing, the superb defense and his uncanny overall court sense and instincts that simply set him apart from the rest of the basketball world -- are on full display this evening.

On one break, Bird has Archibald wide open on the right for a 12-footer and Maxwell underneath the hoop on the left, but guarded. Everyone; including the ballboy, knows the ball has to go to Archibald. The ball lands instead in the hands of a stunned Maxwell, who almost misses the layup.

At another juncture, a baseline drive by Dawkins, about to culminate in a stuff that will send vibrations through the first 10 rows of seats behind the basket, is rudely interrupted from behind by Bird with a perfect block.

Ironically, on any other team, tonight might have been Archibald's show alone. He has gone from a man not even invited back to training camp to the league's best point guard.

And almost unnoticed, as Boston Garden rocks, is Dave Cowens, he of the seven of 39 shooting slump. His intensity has been the 10-year antithesis to the declining effort of so many of those around him. On this evening, only the close observer notes that, as in New York the Saturday before, he still plays the best defense of any center in the league.

When it comes time to leave the building, the departure is a sad one. For the experience has been one of life's great rarities. The Boston Garden has been one great big two-hour smile. Game Five Washington, Dec. 22

Back to the salt mines.

It has been one long ride to get down here, too. For the first half of the ride down from Boston, all I've had to rely on is WCBS-FM in New York, the nation's best port in the storm of contemporary trash that is today's music. The oldies selections, including the four-an-hour journeys into the doo-op file are untouchable.

But what's a good rock-and-roll man to do at this time of year? Half of everything you hear is Christmas music.

Bah, humbug.

Which is also my sentiment about Capital Centre.

Two friends once made a bet. One would start at the Holiday Inn in downtown Baltimore and the other at the Mayflower in downtown Washington at about 6 p.m. on the night of a Bullet game. No speeding allowed, and whoever got there first would win a free dinner.

The driver from Baltimore won by an easy eight minutes, taking 40 minutes to get there.

Since there is no proximity to any civilization in Landover, everyone has to come and go from games at the same time, creating monstrous and unnecessary traffic jams.

Unnecessary if, like Boston Garden, Madison Square Garden and even the Salt Palace, people had an urban area to enjoy in conjunction with a sporting event and could arrive early or stay after for shopping and dinner.

This is not even to mention that there are thousands of kids of high school age in the Washington area who grow up playing basketball and would love to make a Bullet game on a weeknight if it didn't mean getting home late.

This, of course, is exactly the type of broad-based support, with children growing up with the game and passing it on through generations, that other clubs with sensibly located arenas enjoy.

In any case, the Bullets win over the Houston Rockets in a routine 122-114 game before a Saturday night crowd of 8,000.

Elvin Hayes enjoys a good shooting night with little resistance from All-NBA center Moses Malone, who looks more worried about his last-minute Christmas shopping.

Greg Ballard does pretty much what he wants with Rick Barry, another big NBA name playing out the string. Wes Unseld, dependably, works hard to stop Malone at the other end.

About the only Rockets that really seem in the game are Calvin Murphy, who eternally puts forth the effort and enthusiasm of a rookie, and Robert Reid, a 6-8 forward who comes in for Barry.

Mitch Kupchak and Larry Wright have good nights, and if you're a Bullet fan you have a little fun.

But if you were up for a full evening's entertainment, you probably stopped on your way home for some seasonal cheer, or when you finally made it home went looking for a good late movie.

Such is life in the NBA.