On Sept. 21, 1981, more than half a million people overran New York's Central Park to see the first public performance in 11 years by Paul Simon and Art Garfunkel, two angsty meistersingers and ageless Zeitgeisters back from the dead of the '60s. It would have been a crime if a cultural event like this were held and no television record made of it. But one was. It is showing this month and next on HBO, the pay-TV service with more than 8 million subscribers nationwide.

"The Concert in Central Park," premiering tomorrow night at 8 over the Marquee Television Network and Arlington's Metrocable, is the kind of pure musical program that a regular commercial network would be unlikely to present and that public TV couldn't afford. It's simply 87 minutes of songs--21 numbers--performed for an enormous audience by two popular and influential artists, with no gimmickry or doodads as distractions.

The ballads of Simon and Garfunkel prove as apt a balm for '80s ennui as they did for '60s paranoia; when Simon and Garfunkel get misty (they also get happily rowdy), there really is no better music to feel sorry for yourself by. They were always on the cutting edge of hip sentimentality, and yet they managed, and still manage, to look aloof and untouched by what's going on around them.

They look that way even when 600,000 people are cheering them from all sides or when, during one song, a crazy leaps onto the stage and is discreetly hustled off (during a song that mentions the death of John Lennon). The director of this TV version of the concert, Michael Lindsay-Hogg (he also directed a small portion of "Brideshead Revisited"), concentrates on the performers and largely ignores the crowd until the rouser, "Late in the Evening," when he suddenly cuts to this huge rolling plain of people that nearly takes your breath away.

A little later, Garfunkel sings "A Heart That Lives in New York," one of the few songs on the program not written by Simon, and at the concluding line, "So, here's to New York," he raises one arm toward the sky and at that moment the director takes us aloft for a blimp's-eye zoom-out of the scene below.

Lorne Michaels, the executive producer (and the man who created and produced the original "Saturday Night Live"), says from New York that it was decided to stick with what happened on stage. "Our narrative stance was that we'd have the best seat in the house, as opposed to covering the event like 'Woodstock.' That way of covering concerts has become a terrible cliche' in the last few years anyway."

At times, watching the TV version of the concert is probably more satisfying than actually having been there. You can see better and even, under the right circumstances, hear better--if you live in one of the 20 U.S. cities where "Concert" will be simulcast in stereo when it is shown on HBO. But you don't--that is, Washington isn't one of them. The massive forces behind the management of Simon and Garfunkel have deemed the city an unworthy market for a simulcast. The whole thing is tied in with the release of the duo's Central Park album.

A stereo version of the concert was submitted for preview, however, and played back on a Sony KV2645-RS, which is the "Ben-Hur" of television sets (26-inch screen, stereo speakers, bass and treble controls). More and more TV manufacturers are offering sets with improved audio, a pleasant change from 30 years of tiny, tinny speakers crammed into set fronts. New component TV systems, from Sony and other manufacturers, dramatically alter the viewing experience. With the sound cranked up and crackling on "Concert," there's an unexpected side effect: The picture becomes more compelling, too. It's harder to take your eyes off it; you feel much, much more involved.

In a decade or so, when the TV picture grows much larger and the sound system radically improves in American homes, maybe producers and networks won't be able to palm off as many dithery trifles on the public, because people will simply be paying closer attention.

It certainly helps to be able to hear every word of Simon's lyrics. In their opening song, "Mrs. Robinson," on the line, "Look around you, all you see are sympathetic eyes," Garfunkel surveys the vast sea of sympathetic eyes in front of him. On "Old Friends," they sing, "Can you imagine us years from today, sharing a park bench quietly?" And during "The Boxer," it is observed that "after changes upon changes, we are more or less the same."

Simon and Garfunkel strike nerves for more than one generation. "Preserve your memories; they're all that's left you," Simon sings near the conclusion. This beautiful videotape is an eloquent act of preservation for almost all the world to share.