In the bright, refurbished Olympic gymnasium that serves as a courtroom for the trial in one of Italy's most notorious crimes, the killing of former premier Aldo Moro, the amplified voices of black-robed judges, the prosecutors and defense lawyers and defense witnesses interminably drone on.

In more than 400 hours of testimony over eight months by nearly 200 witnesses, only one -- confessed terrorist Antonio Savasta -- has provided any solid information directly related to the mechanism of the crime.

Despite its failure to turn up significant evidence regarding the methods and motives of Italy's most stunning postwar crime, the trial has subjected Italian terrorism to its closest scrutiny yet.

Ten years after first appearing here, Italy's left-wing terrorists -- although still dangerous -- appear directionless, divided and politically confused.

The terrorist movement has been further weakened by the collaboration of a growing number of arrested terrorists with police.

On one side of the room are six heavily guarded steel cages that hold several dozen men and women accused as terrorists. They huddle together within their cells, talking or laughing quietly, and, except for an occasional outburst, they ignore the proceedings.

About 70 people are on trial for their role in the Moro killing and several other Red Brigades crimes in the Rome area. But the six steel cages, each guarded on the inside by a row of five heavily armed Carabinieri police, are also an unequivocal symbol of the fragmented status of the terrorists.

The second cell from the front, empty in the most recent stage of the trial, is reserved for the confessed terrorists, like Savasta. The third belongs to the so-called "guerrilla party," which carried out the December 1981 kidnaping of U.S. Brig. Gen. James L. Dozier. Number four is occupied by the followers of Mario Moretti, the leader of the Red Brigades at the time of the Moro murder. The group generally is known as "the militarists" and includes Moro's alleged murderer. Number five is for dissidents who broke with Moretti over the decision to kill Moro. And the sixth holds several lesser-known terrorists who have "dissociated" themselves but refuse to testify against their former comrades.

Alone in the first cage, slumps tiny Natalia Ligas, 24. Accused of seven murders and innumerable other crimes, Ligas also has been accused -- possibly falsely -- of being a traitor by Red Brigades in Turin. Police say that when she was arrested in Turin she was on her way as an emissary of the "guerrilla party" to a supposed peace-making session that the police contend would have ended with her murder.

In operational terms, the Brigades have suffered a sharp defeat at the hands of the Italian law authorities. Last January, Italian police rescued Dozier, and 826 suspected left-wing terrorists have been arrested and jailed this year.

Overall, 1982 has seen a sharp decline in terrorist acts. Although the Red Brigades have murdered 14 people -- five more than last year -- there have been no more kidnapings and shooting of victims' kneecaps have now almost ended.

But as important as policework has been -- after a new wave of arrests last month all but a handful of Brigades leaders are now behind bars -- the terrorists have clearly been their own worst enemy. Former Genoa university literature professor Enrico Fenzi, 43, told the court that the Red Brigades' crisis began "the day after the murder of Moro."

Following Moro's death "no one knew what else to say or do," said Fenzi. He added that even the Red Brigades' founders, such as Renato Curcio, whom he met in jail, were critical of the "operations."

"In their opinion, the Red Brigades had kidnaped Moro without even knowing why," he explained.

From a strictly legal point of view, the trial appears to be more formal than substantive. The unrepentent among the accused have strictly refused to take the stand, limiting their participation to an occasional written communique and to threats delivered to judges, lawyers and press. The threats are "chilling," said a reporter who is a regular at the trial, "because you know there are still more of them out there."

The scores of witnesses that have filed before the panel of two judges and 14 jurors have included Red Brigades victims and their relatives, police officers, journalists, politicians, Moro's closest aides and the confessed terrorists.

Of these, the most useful testimony in terms of the penal changes came from Savasta, 27, who also was Dozier's jailer. Although his role was limited to tailing Moro before the final kidnap plan was made, and to delivering the stolen car in which the former prime minister's body was left, Savasta is the only terrorist witness shown to have firsthand knowledge of the crime.

The other witnesses have been questioned at length about the Red Brigades crimes. And innumerable sessions have been devoted to going over such "mysteries" as why the main Red Brigades hide-out in Rome during the kidnaping was not discovered sooner and apparently was found only by accident, why investigators supposedly ignored or misunderstood the outcome of a spiritual seance at which the name of the street the hide-out was mentioned, why Moro's prison was never found and whether it was indeed at the address that is now suspected.

Journalists have been grilled about the sources they used for articles, and police have been scrutinized about whether they really did their duty. And politicians have been queried closely about whether they really tried to save Moro and what kind of contacts they established with the Brigades in their attempts to do so.

Perhaps most dramatic was the tight-lipped testimony in July of Moro's widow, Eleonora. She not only accused Moro's fellow Christian Democrats of letting him die, but she also alleged that her husband's pre-kidnap request for a bullet-proof car had been ignored.

At one point in her testimony, Moro referred to alleged threats her husband had received in the United States with regard to his long-term, open-door policy toward the powerful Italian Communists.

Moro's close aide, Corrado Guerzoni, testified about a harsh exchange on this subject between Moro and then-secretary of state Henry A. Kissinger, in Washington in 1974 when Moro was foreign minister. But he did not say anything about explicit threats.

One reason for the lengthy and detailed nature of the trial is the Italian judicial process, according to which everything that emerged in the long, pretrial examination process has to be repeated in open court.

Judge Severino Santiapichi appears determined to give the proceedings their due importance.

"Moro and Italian terrorism -- these are now topics of historic importance and the court has decided to make this a historic trial," he said.

Late last month, the court ended its first phase of judicial examination and called a brief recess. This month, the prosecution and the defense are to enter their pleas.