TELEVISION, THE good news machine, departs from its role as national comforter tonight when NBC begins the four-night telecast of "Holocaust," a 9 1/2 hour filmed drama on one of the most discomforting of all possible topics: Nazi persecution and extermination of Jews in the 1930s and '40s. It is hard to imagine television drama more demanding or rewarding.

For years, TV has taken subjects that seemed to defy sugar-coating and turned them into mind snacks - subjects like death, for instance, depicted as everything from cute to noble but never quite ghastly. The people who made "Holocaust" are shrewd dramatists, and they tell absorbing, interwoven stories about fictitious, believeable people that hold one's interest through almost every minute of the 450-minute film, but they have not - to their great credit - minimized or trivialized the reality of horror against which these lives are led.

If anything, the horror takes on an immediacy that a documentary treatment would be hard put to equal; for years and years we have heard of the systematic execution of "6 million Jews" by the Nazis; "6 million is inconceivable. It can't be grasped. But the sight of a middle-aged doctor we have come to know kneeling on the floor of an Auschwitz barracks and weeping of his dead wife is a penetrating, agonizing image; it is conceptually and emotionally accessible to everyone.

Television has the capability, little utilized, of making the abstract, even the unimaginable, personal and particular. For this reason and because it has been skillfully done, "Holocaust" could have more impact on a greater number of people than any other treatment of the subject.

"Holocaust" requires a substatial commitment of time from viewers. It begins with a three-hour chapter at 8 o'clock tonight on Channel 4 and continues with two-hour episodes Monday and Tuesday at 9 p.m. and a 2 1/2 hour conclusion Wednesday at 8:30 p.m. But the project is demanding in other ways, because it it not the kind of no-fault television we are used to.

One question asked since the program was announced is, "Why bringthis all up again?" People have been heard to say they will not watch the program because they do not want to be reminded of "such things." There are those who seem not to care enough and those who porfess to care too much; "I won't be able to watch it," said one woman by telephone last week.

I'd get too emotional. I'm already aware of that situation. It's too painful."

But one of the central and self-justifying piints of "Holocaust" is that we have to be made aware again - not just of what inhumanities the Nazis committed in the name of nationalism, but of what our fellow civilized, 20th century human beings are capable of inflicting on one another. To witness again the consequences of bigoty in its most virulent extreme is truly to confront the nature of a beast that has hardly vanished form the battered face of the earth. Of course this is painful, but where did we get the idea we should spare ourselves all forms of pain? Probably from television, as a matter of fact.

It is not dishonorable to turn to television for escape and frivouty or to want to avoid being depressed, especially by something that is still at heart an entertainer and care-chaser. But there are different kinds of depression. Actor George those of the "Holocaust" cast was asked at a New York press conference if the actors found it "depressing" to work on the production.He said, "Actors do not get depressed when asked to cope with the serious. Actors get depressed when they are asked to cope with something banal and crummy and third-rate." One feels depressed after watching "Holocaust," but it's not the depression that comes from having been played for a fool, from realizing one has spent hours in front of a television set without feeling a single substantial human emotion.

"Holocaust" is not a work of art, and at times it is as slickly artless as most TV shows. Writer Gerald Green and director Marvin J. Chomsky are accomplished craftmen, hovwever, and given the limitations of production and preparation time, they have made few serious mistakes. Occasionally, expossion is clumsy - "It's Passove . . . April 19, 1943," a man in the Warsaw Ghetto announces to his comrades. And at the end of tonight's episode, a young man and woman meet on the streets of Prague and fall in love as quickly as any movie lovers ever have.

"But the quality of acting and storytelling is generally at a much higher level than in other long-form TV productions. Perhaps most commandably, "Holocaust" is not a "docu-drama." There are only two minutes of newsreel footage in the entire film, in addition to some still photographs taken at actual concentration camps. Also, though some actors play real people - Eichmann, Himmler - whose lives interact with Green's characters, the emphasis is always on the effect of the Holocaust on individuals. Producer Robert Berger says that the creators of "Holocaust" strove for "a dramatic truth that may be as important as any historical truth," and they achived it, perhaps more tellingly than they imagined they could.

Naturally, "Holocaust" will be compared, favourably or unfavourably, to "Roots," which aloo concerned the plight of an opressed people. But the film was by no means made in imitation. Green's 200-page treatment for "Holocaust" arrived at NBC from the printer just as "Roots" was being televised. Admittedly, the success of "Roots" did increase the chances that Green's project, originally conceived as eight hours and later expanded, would get on the air.

As in "Roots," the highly charged nature of the material seems to have inspired many of the actors in the cast to an almost other-wordly effectiveness. Most of them are introduced in the first episode, when the two principal families, the Weiss family and the family of Erik Dorf, are briefly united at the marriage of son Karl Weiss to Inga Helms, a Catholic, in 1935, before the Nazis passed laws against intermarriage with Jews. The episode is titled "The Gathering Darkness" and it gathers swiftly.

The central characters are Dr. Josef Weiss and his wife Berta, played by Fritz Weaver and Rosmary Harris, and Dorf, who is played with spellbinding intensity by Michael Moriarty. This man, who rises from anonymity into the high ranks of the Gestapo, is driven not by hatred or racism but bt desperation and bureaucratic ambition. Through the baby-faced Dorf, more than any other character, Green brings the spectre of Nazism into a new focus - a valuable focus after years in which words like "fascit," "racist" and "genocide" have been overused almost into meaningless - so that we can see its psycholocial and cultural origins and its pathos, and not just the fact that it was monstrous. Monstrousness, as it has been depicted in many films, books and TV shows about Nazis, is really a rather managable idea. The boy next door turning mass murderer is not.

So many actors excel that they become a single functioning unit with few weak links. Weaver and Harris are faultless. Joseph Bottoms shows truly surprishing strength as Rudi, the Weiss's son, who escapes Germany and eventually becomes a partisan rebel fighting the Nazis. Tovah Feldshuh conveys earthiness and fragility as the girl he eventually marries. Others outstanding include Anthony Haygarth as Muller, George Rose as Lowy, Meryl Streep as Inga, and David Warner as Heyrich.

In later episodes, Robert Stephens, who plays Dorf's Uncle Kurt, is especially, intimately moving as a voice of shocked conscience from within the Third Reich, and Murry Salem makes a sensational, forceful impression as Anilevitz, who symbolizes the new Zionism and is one of the leaders of the Warsaw Ghetto uprising in 1943.

Green has been careful to avoid painting characters or issues in strict blacks or whites. Genocide cannot be acceptably explained no matter what, of course, but Nazis rationalized it to themselves. The gulit was hardly theirs alone. "Few governments will stick their necks out for the Jews," Dorf tells Heydrich, and he was proven correct. The United States "is turning away German Jews" as immigrants, Weiss tells his family. Later Dorf warns a priest who has spoken against the persecution of Jews, "Church leaders are supporting our policies," and many did, or acquiesced in silence.

Finding the blameless is more difficult than identfying the culpable. "You'd be surprised," Dorf tells Eichmann, "how Jewish leaders cooperate with us" in the early stages of deportation and confinement, and even after the persecution has escalated well beyond madness, Heydrich notes, "The French and English barely protest."

And though the drama is about the effect on a Jewish family, it is also noted that others were persecuted and destroyed - homesexuals, gypsies, Jehovah's Witnesses and "the feeble minded."

Obviously there is great potential for bathos in telling the story of the Weiss family, but if anything, Chomsky and Green have been more restrained thn necessary. "You can't direct unless you develop a surgeon's attitude," Chomsky says. "If I allowed my own personal emotions to enter into it, I might lose a sense of balance. I would end up producing a piece of propaganda. We didn't want that."

At times, through,Chomsky went too far in the other direction, because certain scenes that should be devastating come off as muted or blurred. The decision to eliminate much of the haunting music Morton Gould wrote for the program may have been unwise, because some scenes play very flatly, no matter how much the actors are putting into them.

There are eloquent touches, however. The years of 1937 and 1938 and the mounting Nazi furor pass by in a montage accompanied by the oblivious piano practice of Mrs. Weiss and her daughter Anna; they are playing Morzart on the family's treasured Bechstein. Mozart soon gives way to Wagner in the land and the piano is eventually confiscated - after the Weisses have been uprooted - and given to Dorf.

At the close of part three, Dorf's Aryan family gathers around that piano for Christmas carols. Dorf's young sons are wearing swastikas on their arms. They sing "Oh Little Town of Bethlehem" while photographs of the Weiss children, which had been found in the piano, are burned in a fire. If the imagery is obvious, it is also trenchant and affecting.

The filmmakers chose not to flinch from scenes of murder and torture; we see men, women and childred stripped of their clothes, stood up in front of ditches, and shot, or led to gas chambers. An artist who has secretly drawn anti-Nazi pictures has his hands broken as punishment. In the last chapter, when the band of partisans fights back and liberates a prison camp, the violence is unusually explict for television.Very young childred should probably have the benefit of adult comapnionship if they are going to watch "Holocaust."

There is one disturbing aspect to the violence, however cathartic, in the final program. Thoughout "Holocaust" the author expresses dismay, through dialogue he gives characters in the film, over the fact that more Jews did not fight back against their oppressors. The Nazis marvel at how silently and even willingly Jews are marched first to imprisonment and then to death.

"Holocaust" was made, Green has said, in tribute to those Jews who "fought back." The implication is that those who did not dies less honorably than those who did. Green sees precedent in Christian history for the fanatical anti-Semitism of the Nazis - he also makes reference to the social conditions in Germany between the wars that were so conducive to a search for scapegoats - and he expects Jews who lived in Germany in the '30s to have seen it, too.

Yet what happened remains unthinkable even now. It's risky hidsight to blame those who couldn't see it coming.

"Holocaust" may seem to start slowly, but the story builds momentum and becomes an increasingly compelling experience, until, finally, the sense of shame and tragedy is overwhelming, on a level perhaps more profound and certainly less relenting that "Roots" - and wihtout question to a degree nearly unprecedented in TV drama.

The film was screened for the press and religious leaders without commercials, but with breaks where commercials will be inserted. NBC has promised through spokesmen that the number of interruptions will not be excessive and that sponsors are cooperating by submitting their least abrasive and clattery ads. But this is still commercial television, and the program in fact represents one of those moral victories for the commercial television system that come along rarely. Ironically enough, considering its subjects, "Holocaust" is a moment of glory.