During his senior year at the University of Montana, Micheal (Sugar) Ray Richardson was assigned to write an essay about his "experiences as a black athlete." In a two-page handwritten paper, Richardson wrote:

"My experiences as a black athlete. I feel that as a black athlete you have to do a little more on the floor, and a lot off the floor. I found that you must be able to ajust to many people. No matter were you go people will never be the same.

". . . I went to 95% black high school. Everyone on my team were black. When we would play games the officials would try to make us loose just because we were all black. They did not want a all black team in the state. But we had to go out and play that much harder . . .

"I new when I left home that things would not be the same. You have to give less and take more. I look at people as people, not what color they are, so it was not that hard for me to ajust. I think that white people our more understanding then blacks, because they no how to talk to each other . . .

"The people here our great. I feel that they like you for what you our not for what color. If I had to do it over again I would do it the same way. I now this is something that I want forget."

I thought about that essay last week when Richardson, the New Jersey Nets' playmaker, was banned from playing in the NBA for at least two years after he tested positive for cocaine.

I had first seen the essay two years ago, when I was preparing a story on Richardson for Sports Illustrated. At the time, I wondered how Richardson, with his limited command of the English language, had remained academically eligible to play basketball through three years of high school (in Denver) and four years of college. But last week, as I reread the essay, I wondered only about Richardson's future. He will be 31 in April, and he has been schooled to do little more than play basketball. What will he do now?

Sadly, last week's disqualification wasn't surprising. In preparing the magazine story, I spent several months interviewing dozens of people who had played varying roles in his career: friends, coaches, agents and family members. What emerged was a portrait of a roller-coaster career that never was quite on track.

Richardson came aboard the roller coaster in the spring of 1978, after his senior season at Montana. Buoyed by the likelihood that he would be selected in the first round of the NBA draft, he borrowed more than $13,000 from an agent to buy a Datsun 280Z. But a month later he had a new agent and a new car, a Pontiac Grand Prix. And when the New York Knicks made him their No. 1 draft choice, "He went out and bought a silver Rolls Royce," a friend in Denver recalled. "He even had a chauffeur. A former high school teammate used to drive him around town." Peak of His Profession

By his third season, Richardson was perhaps the best playmaker in the NBA. He twice had been chosen to the all-star and all-defensive teams and twice led the league in total steals. He was prosperous, the Knicks having extended his contract at an average salary of $350,000, and he was glamorous, having posed for a shoe company poster that displayed him in a white top hat, tie, tails and sneakers, standing smugly in front of the Manhattan skyline.

But off court, Richardson's life was as gray as that skyline. He was hiring and firing agents as quickly as he was buying and selling new cars. His savings were almost depleted. His wife was pressing for a divorce. And he had made a deliciously dangerous discovery: cocaine.

He had first used the drug with some friends in Denver, according to an acquaintance, former NBA player Anthony Roberts. "We thought we were pretty cool," Roberts recalled. "We just tooted snorted cocaine . We didn't do it that many times." Later, according to Roberts, another NBA player introduced Richardson to free-basing, the method of cooking cocaine to its purest form, then inhaling it through a pipe.

In the summer of 1981, Richardson was confronted about his cocaine use by a former high school teammate, Wayne Johnson. "Well, yeah, I do it every once in a while," Richardson said, according to Johnson. "It won't do anything to you. It's just a nice little easy high and it won't do nothing to affect your body. You ought to try. It's real nice."

The Knicks were aware that Richardson's life was chaotic, and David A. (Sonny) Werblin, the club's chief executive officer, offered him some advice.

"I suggested that he shouldn't waste the opportunity he had living in New York, that it was possible to take classes at almost any hour of the night," Werblin recalled. "His answer was, 'Man, I don't have to do that. I got my business degree.' " Richardson later admitted that he doesn't have a degree from any school.

"I don't think Micheal Ray is literate at all," Werblin said. "I doubt whether he reads or writes . . . A kid like Micheal Ray has done nothing but play basketball. It's a commentary on our educational system."

In November 1982, after disappearing from the Knicks' training camp, then missing a team flight to Washington, D.C., Richardson was traded to the Golden State Warriors for forward Bernard King. Two months later the Warriors hired a detective agency to provide them with details about Richardson's private life, and on Feb. 6, 1983, with the surveillance still in place, Richardson was traded to the Nets.

The Nets didn't know that Richardson was addicted to cocaine. But they soon found out, and after the conclusion of the 1982-83 season he was admitted to a drug rehabilitation hospital in New Jersey. Three weeks later he was out, pronouncing himself cured.

He wasn't.

He entered a treatment facility in Minnesota, then called a news conference in September to denounce the evils of cocaine. But a week later he disappeared from the Nets' training camp, checked into a hotel and used cocaine with some acquaintances. He surfaced four days later when he phoned his agent, Charles Grantham. "The lifestyle that basketball has created for me, I can't handle that," Richardson told Grantham. "Maybe I'd be better off driving a truck."

Grantham urged Richardson to persevere, and he did. He changed the spelling of his first name (it used to be M-I-C-H-A-E-L), averaged 20.1 points per game and was named the NBA's 1984-85 Comeback Player of the Year. The Nets showed their appreciation with a four-year, $3 million contract.

But the roller-coaster ride wasn't over. Last December, in the middle of a hot streak in which he was averaging 20.4 points, 8.7 assists and 6.5 rebounds per game, Richardson disappeared for three days, then admitted himself into a rehab center in Los Angeles. Disqualified from NBA

He rejoined the team on Jan. 20 but, last Tuesday, NBA Commissioner David Stern announced that Richardson had tested positive for cocaine for a third time, which, under terms of the league's anti-drug policy, called for his immediate disqualification from the league. (He can apply for reinstatement after two years.) In announcing the ban, Stern said: "This is a tragic day for Micheal Ray Richardson, nothing less than the destruction by cocaine of a once-flourishing career."

Has Richardson's career been permanently destroyed? Probably not. Already, there are ripples of interest in Richardson from clubs in the European Basketball League, where star players can command low six-figure salaries.

"But that's not our priority," said Grantham, who also is executive vice president of the NBA Players Association. "Our priority is to get Micheal some intensive treatment so he can get his life back on track. If Micheal progresses, I think he can play in Europe next year, then, if he does well over there, he could probably come back to the NBA for a year or two. I think Micheal will play basketball again. After all, that's what he does best."

For better or for worse, that's all Richardson really knows how to do: play ball. Last week, as I was reading Richardson's college essay, I wondered if the system that had taken him from a Denver ghetto to the University of Montana to NBA stardom hadn't failed him. Grantham wondered, too.

"There are no easy answers," Grantham said. "You can blame the system for not properly educating Micheal and for not preparing him for the pitfalls he would face as a professional athlete. Yes, the system has failed Micheal. But Micheal has also failed himself. I don't think there's any doubt about that."