On Jan. 30, just as he was about to cash $43,500 in chips -- a modest day's earnings, you might say -- security guards told Ken Uston his days at Atlantic City's blackjack tables were over.

So it was that Uston -- a professional "card counter" who is a legend at the blackjack tables -- managed to get himself banned from what he says is the last casino in the world that would let him play.

Now, a the age of 42, Ken Uston is fighting like a gentleman insulted in the drawing room.

Next week, the New Jersey Casino Control Commission will begin to hear arguments from Uston and the Resorts International casino over the merits of allowing card counters to play. "Card counters" rely on memorized odds tables and other systems to defeat the house, but Resorts claims, through spokesman Leon Zimmerman, that they abuse what the law states should be "a game of chance" by turning it into a game of skill.

"If skill is involved in a game," counters Uston, "it's inherent in the rules of the game. If they choose to offer a game of skill and they choose to not let the skillful play, let them make the game tougher, move thefences out. But don't just abolish the skillful."

In the mid '60s, with the publication of Ed Thorpe's "Beat the Dealer," card counting was brought to national attention. A mathematics professor by trade, Thorpe worked out a computer model and then tested it at the blackjack tables of Las Vegas. When he won and wrote about his experiences, casinos began to watch closely for counters.

And counters became marked men. as much as if they were playing with a marked deck. They were spotted by pit bosses and thrown out of casinos. Some resorted to disguises -- as elaborate as a complete Oriental impersonation, or as simple as the wig and glasses USTON SOMETIMES RESORTS TO.

But beyond the false hair and makeup, it is really their betting patterns that reveal card counters at the blackjack table. Because of the numerical certainty of a game designed to reward players who come closest to 21 without going over, a skillful counter can ascertain when his probability of winning is optimun. And he will then increase his bet from, say $25 to $1,000. With that spread, the counter can expect to earn about $400 an hour -- not bad work, if you can get it.

Thorpe's book appealed to Uston, a graduate of Yale (where his father had taught linguistics) and of Harvard business school. He'd worked as a computer analyst for the telephone company in Connecticut, and was senior vice president of the Pacific Stock Exchange in San Francisco.

"The real beauty of blackjack," he says, "is the pure mathematics of the cards. It's not like poker where there's a strong psychological element, or other games that rely mostly on chance. I'm being honest when I say that I love blackjack. It's the thing I like more than anything -- except playing the piano. I'm hopelessly addicted to Erroll Garner."

By 1974, Uston had quit his job and become involved in a team of card counters who traveled to the world's blackjack tables, altering their techniques to suit house rules. "In seven months," Uston says, "we won $480,000. Then I decided to start my own teams.

"The secret," he says as he demonstrates, "is not so much the counting itself. There is simply an arbitrary value assigned to each card and the player keeps a running count of the value of the deck. The trick is being able to analyze the dealer's up card versus your hand and the odds of the remaining cards, and then knowing how much to bet."

"Kenny Uston," says one pit boss at Caesar's Palace in Las Vegas, "is one of the most amazing card players I've oever seen. There's an almost esthetic beauty to the logic of his betting. I like watching him so much that I almost hate to throw him out."

Uston is part of a fascinating chapter in the history of gaming, made up of a new breed of gambler who can have mathematical confidence in his chances.

"There were probably some early guys in the '20s," he says, "who had an innate sense of counting, but nothing of the precision we have now."

Uston has the longish hair of the jazz musician he aspires to be; the smartly cut suit of a hip lawyer; the soft speech of a divorced man who's spent a lot of time in the mellow side of California. The only thing that stands out is a huge medallion he wears around his neck; it's the logo of a Las Vegas condominium he invested in. Ken Uston just doesn't look like the sort of gaudy, flamboyant character who's been a traditional part of America's gambling mythology.

In Puritan New Engliand, "playing cards" was considered the most heinous sin of all kand yet, by the time of the Continental Congress, Thomas Jefferson was keeping track of his looses at the card table and Ben Franklin himself printed playing cards. Later Abraham Lincoln filled idle hours with poker games.

By the turn of the century, card players had become great men of legend. Richard Canfield set up a casino at Saratoga that made the bets on the khorses seem paltry by comparison. "Bet-A-Million" Gates literally did that, declaring "I want to lay down enough to hurt the other fellow if he loses and hurt me if I lose." And by the Roaring Twenties, Arnold Rothstein's casinos were not only legendary -- but also continuously raided by police.

Legends sprang up. "The Man Who Broke The Bank at Monte Carlo" was a popular song. Rothstein became the model for the Nicky Arnstein character in the play "Funny Girl."

"There are so many myths," says Uston. "The Monte Carlo song was apparently about a man who caused all the chips at a particular table to be used up. The bank actually wasn't broken. I've done that a dozen times.

"The only real case of the bank being broken that I know of happened about two years ago at Dieppe, France. Our team won significantly to the point of the owner not having enough money to cover our bets. He had to give us post-dated checks and sold his farmhouse and had his casino taken away.

"People talk about the thrill of the hunt," Uston says, "but it's more a matter of hard work. In that sense you could say I'm part of a new breed. There's really no gamble in me. I never bet on anything unless I have the edge, which in blackjack averages out to about 1 1/2 percent."

Uston hardly seems like the wildbetting high rollers who flock to casinos, although he will on occasion put on a drunken act to try to delude pit bosses, Beneath it all he's coolly scientific, once resorting to a concealed electronic calculator that was seized by FBI agents who tried unsuccessfully to make a fraud case against him.

"People always ask me what kind of car I drive," he says, "I'm not into material possessions. I have a MG Midget and a '69 Chevy. I do have this fancy gold chain probably worth four grand, because it's all gold and diamonds. So if people want to look for the stereotyped image of a gambler, they can see that. Most of my money is in real estate.

"My only real weakness is that I love music and I collect instruments and stereo systems. And women, of course. But I don't even wear a watch. I don't want to know what time it is or where I'll wake up tomorrow morning."

Uston claims there are 18 simple rules of strategy anyone can learn to stay even in blackjack. But in order to win, he claims, a player must study for a minimum of 100 hours, memorizing complex tables and matrices that tell the relative odds of a bet.

"It sounds easy," he says, "but it does require a tremendous amount of concentration, and I don't think anyone can do it unless he really loves the game. And even breaking even doesn't mean that there won't be tremendous swings at the table. On, skay, $25 or $50 bets you can easily go down $3,000 before the odds come around."

Uston will be teaching a week-long course on his methods here beginning today at the Mayflower Hotel. He's also written several books, including a new one on his experiences at Atlantic City called "Let's Hope Reality is Based on the Movie." A book on his team plkaying, "Big Player" has been bought by Frank Capra Jr. for filming.

"I really didn't want to get involved with Hollywood," he says, "but they told me I could play piano in the film."