What was going on when I was born?

LAST week began well for Walter Yetnikoff, president of CBS Records. On Monday, Michael Jackson's ''Thriller'' album, which has sold 21 million copies under CBS's Epic label, got 12 nominations for Grammy Awards, the record industry's answer to Hollywood's Oscars. That night, the young performer walked away with most of the American Music Awards. But on Tuesday, the music turned sour: the Supreme Court, in the Betamax decision, upheld the legality of television taping at home and dealt a blow to the record industry, which has lost billions in sales to the unauthorized taping of music. On balance, however, CBS Records is on a roll, and so is Mr. Yetnikoff. ''This has been the best year we've ever had for CBS Records profits,'' he said, in an office tiled in ''platinums,'' the prizes handed out by the Recording Industry Association of America for albums that sell over 1 million copies and singles that sell over 2 million.

In a restaurant five minutes from the Cinecitta studios in Rome, Federico Fellini, the undisputed superstar of Italian film, was having lunch. With him was his entourage - his writers, editor, press representative and other colleagues from the set. People came over to the table, including Marcello Mastroianni, to greet the Maestro, as everybody called him, to hug or kiss him or just to say affectionately, ''Ciao, Federico, ciao.'' Mr. Fellini is what you would expect: expansive, grand, charming, witty, gracious, and thoroughly himself - like a character from his films. There is also another Fellini: thoughtful, intelligent, wise, and completely realistic. Over lunch, both Fellinis appeared.

AS condominium officers have discovered over the years to their chagrin, the arrival of new unit owners can often trigger trouble. Some newcomers are only vaguely aware of the condominium's rules; others know the rules but nevertheless resist furiously when they are told they cannot let their dog run free or leave their car anywhere they choose. Not all new neighbors are troublesome, of course, but there is now sufficient concern among residents of both city and suburban condominiums to spur the introduction of more comprehensive admissions and screening procedures. In the past, buying a condominium tended to be similar to buying a single-family house. If buyer and seller agreed on a price and the bank approved the mortgage, nobody else entered the picture.

No doubt you've seen a woman who looks like Woody Allen's latest heroine somewhere, someplace before - certainly not in one of Mr. Allen's earlier films, but maybe sipping daiquiris at the bar in Caesar's Palace or chain-smoking in some chintzy nightclub in New York. She wears ruffled shirts, tight slacks and a gold name chain around her neck; keeps her blonde hair teased in a 1950's ''do''; and she never goes anywhere - even at night - without a pair of sunglasses clamped firmly on her nose. When we first meet Tina Vitale in ''Broadway Danny Rose,'' she is screaming - in a nasal Brooklyn accent - at her fickle boyfriend on the phone. ''I don't buy it,'' she says, chomping fiercely on a stick of gum. ''You're lucky I don't stick an ice pick in your goddamned chest.'' Tina, an interior decorator with a penchant for jungle-motif rooms, happens to be the mistress of Lou Canova, a small-time nightclub singer, who is managed by the movie's title character - the hapless Danny Rose. Danny Rose is played by Mr. Allen; and Tina, by Mia Farrow.

O nly 52 percent of the people who were eligible to vote in the last Presidential election did vote, a fact that may be regarded angrily, mournfully or simply shrugged off. Undeniably, however, in any measure of voter participation, the United States is near or at the bottom of the list of Western democracies. Moreover, in the past 20 years the percentage of people eligible to vote who did not vote has risen steadily. ''Who or what is responsible?'' an admirable ABC program, ''Voting for Democracy,'' asks right off the bat at 12:30 P.M. today, and then goes on to identify, if not the who's, then at least some what's. One what scarcely mentioned, however, is television itself. Voting statistics, in their way, are almost as tricky as crime statistics. Clever people can turn them on their head. Demographers, for instance, can prove that the decline in voter turnout has to do with age: When the population is young, the turnout falls off because young people do not vote as regularly as older people. Therefore, when the population ages, voter turnout will increase. At the same time, the less well educated do not vote as often as the well educated, and the poor vote less often than the rich. Along with age differences, you must factor in socio-economic status, too. The decline in voter turnout defies simple explanation.

O FFICIALS of the county's three largest cities expect to learn this week whether they will receive a portion of sales tax revenues that has been collected by the county and rebated to the cities in return for higher county property taxes. The decision rests with County Executive Andrew P. O'Rourke, who must authorize the county tax warrants, or bills. Mr. O'Rourke was insisting on certain conditions last week, however, which had not been accepted by all the municipalities concerned. Affected are Yonkers, Mount Vernon and New Rochelle where, under the so-called Yonkers Plan, county property taxes are increased by an amount equivalent to the sales-tax revenues those cities forfeit to the county. The practice, essentially a trade-off between the two taxes, was put into effect in 1974 to allow Yonkers, which had reached its legal property-taxing limit of 2 percent, to raise needed revenues. The other two cities, which have not reached their limit, adopted the option last year after the county increased its share of local sales taxes from 1 to 1 1/2 percent. By joining the plan, they have been able to retain the full 2 percent portion of the sales tax.

In Politics, To Be Ahead Is to Worry Public opinion polls can have a way of unsettling a front-runner, especially when live voters have yet to cast a ballot. So Walter F. Mondale, stationed firmly at the head of the Democratic pack last week by the latest Gallup Poll, campaigned like an also-ran. The former Vice President, who, according to the survey, has increased his lead over Senator John Glenn to 47 percent to 16 percent, lambasted the Reagan Administration's ''assault on women's rights'' and tiptoed around the issue of gun control.

As debate continues over the continued presence of the Marines in Beirut, senior diplomatic and military officials now acknowledge that the Reagan Administration seriously overestimated how quickly the Lebanese Army could be made into an effective force. The marines were deployed in September 1982 with the promise that they would be withdrawn quickly and that the Lebanese Army would then take over internal security. But a few weeks after the deployment, a special Army commission found that the Lebanese Army had only half as many men as previously estimated. A senior Defense Department official involved with retraining the army said many of the men on the payroll ''hadn't been in uniform for years.'' State and Defense Department officials, Congressional aides and others who were involved in many of the initial decisions on the Marine deployment also said the Administration erred when it decided that it need not consult the leaders of Lebanon's factional militias before deploying Marines at the Beirut airport.

TAMPA, Fla. W ith Super Bowl XVIII, the National Football League will overshadow, for today at least, the remarkable impact on the sport that the United States Football League has made in recent weeks. But not far from the Super Bowl site here, and throughout Florida, Arizona and California, the young league will open its second season tomorrow with training camps in 18 cities. All the recent noise and controversy have arisen without one U.S.F.L. player stepping onto even a practice field. How much deeper an impact the league will make is hard to determine. But it is now on its way to altering pro football dramatically in at least the following ways:

DAISY EDMONDSON and Stewart Alter, both magazine editors, left their small Greenwich Village apartment eight months ago because they had just had a baby and, what's more, their landlord had doubled the rent. After ''systematically'' canvassing neighborhoods just outside Manhattan for an affordable house to their liking, the couple finally bought a brownstone for $78,000 in the Sunset Park section of South Brooklyn. ''It's a pretty poor area - there are no restaurants and the shopping is horrible,'' Miss Edmondson said. ''Things have gotten to the point where people like us have almost nowhere to go.'' The house market in Connecticut was also a ''real jolt'' for Fritz Saenger, a marketing executive with Union Carbide Corporation, and his wife, Gretchen. Coming from Ashtabula, Ohio, where $100,000 buys a fine house, the couple were staggered by prices in the Wilton area last spring. ''We had told ourselves that $200,000 was our absolute, absolute ceiling,'' Mrs. Saenger said, ''but after you look and look and look, you say what the heck and you go ahead and pay more. Now we'll have to struggle a little harder to pay the bills.'' The Saengers bought a four-bedroom contemporary house in Ridgefield for $210,000.

The Reagan Administration is preparing a legal challenge to a decision by a Federal judge who ordered millions of dollars in back pay and raises for women found to have been paid less than men holding jobs of comparable worth. Officials at the Justice Department and the White House said they knew a challenge to the judge's order to the State of Washington would be unpopular with women's organizations, which hailed the ruling last month as a new weapon in the fight against sex discrimination. But the officials said political considerations would not deter them from challenging what they saw as a dangerous legal precedent. Worth of Work Is Issue In his decision, Federal District Judge Jack E. Tanner found ''overwhelming'' evidence that the State of Washington had illegally maintained ''a compensation system which discriminates on the basis of sex.''

After decades of a trend in architectural design that produced high-rise structures with featureless rooflines, many developers now are demanding designed tops for their buildings that will make distinctive statements on the city's skyline. For Sterling Equities, the developer of a 28-story cooperative apartment building now going up on the corner of 49th Street and Second Avenue, it was so important that the new tower have a distinctive roofline that it commissioned one architectural firm - Schuman, Lichtenstein, Claman & Efron - to design the building and another - Arquitectonica International Corporation of Miami - to do ''the top and the bottom,'' as a spokesman for Sterling put it.