What was going on when I was born?

President Jose Napoleon Duarte's Christian Democratic Party claimed an upset victory in national elections here today. President Duarte, speaking in an interview, said he believed his party had won at least 31 seats, giving it a majority in the powerful National Assembly. The contention was supported by a national exit poll carried out by the Spanish International Television Network. The poll, based on a survey of almost 11,000 voters, indicated that Mr. Duarte's party would win a majority of at least 32 seats in the country's powerful 60-member National Assembly. The Miami-based network conducted a similar poll after presidential elections here last year that was within four- tenths of one percentage point of the final result. Official returns from the contest for the National Assembly

Because of a mechanical error, credits were omitted in The Living Section on Wednesday for an illustration and photographs with an article on Passover foods. The drawing was by Mark Podwal and the photographs were by Fred R. Conrad.

A table in Business Day on Thursday with the Market Place column misstated the 52-week low and high prices for Bankers Trust stock. The low was 37 3/4 and the high 66.

Perhaps at a different time and in another conference, St. John's would have reigned supreme. But this was Georgetown's year. And while the St. John's players were numb, initially, after their third straight loss to the Hoyas, they seemed to awaken, as the hours passed Saturday night, to the realization that they had shared time and space with a team destined to be remembered for generations. The Hoyas have been to the Redmen what Muhammad Ali was to Joe Frazier: a presence that comes along once in a long while and dwarfs the great accomplishments of otherwise successful athletes.

Having conceded Japanese superiority in low-priced small cars - at least for now - Detroit is bracing to meet its adversaries head-on in a marketing battle over the $10,000 car. Japan's relaxing of its auto export restraints, effective Monday, comes as no surprise to car makers in the United States. Detroit has used the period of restraints to undergo the most thorough rebuilding in its history and has positioned itself to concentrate on the intermediate price range, where Japan's cost advantages will not be so punishing. Indeed, the cornerstone of Detroit's plan for coping with the easing of the export restraints following four years of quotas is to buy large numbers of small cars in Japan to sell here under American labels. And while these so- called captive imports fill out its model lines, Detroit's true test will come in the compact and small-specialty segments of the auto market.

It is always a deep, emotional moment, one that high school and college coaches endure each year as athletes leave their institutions for greater challenges. The annual rite is never easy, but late Monday night, as the final seconds tick in college basketball's national championship game, it will be especially difficult for the Georgetown coach, John Thompson. He will be saying goodbye to someone who has had a major impact upon his life. He will be saying goodbye to Patrick Ewing. Ewing, the center who has dominated college basketball for four years, will play his last game for Georgetown against Villanova in the National Collegiate Athletic Association championhip here at Rupp Arena. ''I know it's coming,'' Thompson said today. ''But I don't do a lot of pondering. As a high school coach, I learned to get used to kids moving on. You can only hope that you've done as much as you can to prepare them to take the next step and that the person who's there next will help him make the adjustment.''

The Cuomo administration today banned commercial fishing for striped bass in New York Harbor and along both shores of western Long Island because of dangerous levels of PCB's in the fish. However, fishing off eastern Long Island, where the bulk of the commercial catch is taken, will be permitted, even though PCB's have been detected in striped bass caught in those waters. In addition, the State Health Department will advise women and children not to eat striped bass from any New York waters and adult males to restrict their consumption of the fish to one meal a month. PCB's have been shown to cause cancer in animals. Recreational fishing for striped bass will be permitted to continue in coastal areas because, otherwise, the tourist industry would lose more than $5 million a year, the administration said.

''Chappy'' Rich turned his face away from the opened firebox and quickly threw fresh pine slabs into the blaze. The boiling sap frothed higher, sending clouds of sweet steam over the cow pastures. The fire in Mr. Rich's maple sugar house is burning 12 hours a day now, as he races the warm weather to boil the last sap run of the season. The thick syrup flowing from his evaporator in a dark amber hue is a sure sign of spring in New England.

The Hospital Corporation of America, the nation's largest hospital management chain, and the American Hospital Supply Corporation, the largest distributor of hospital supplies, said yesterday that they had agreed to merge. The deal is expected to spark other mergers and acquisitions among the largest companies in the country's $400 billion-a-year health-care industry. Based on Hospital Corporation's closing price Friday of $46.50 a share, the combined companies would have a market value of about $6.6 billion, making the deal one of the largest mergers in history outside the oil industry. In the last two years, spurred by changes in Medicare regulations that provide reimbursement on a fixed-fee schedule, and by new corporate health insurance plans that discourage long hospital stays and expensive procedures, hospitals have scrambled to cut costs and operate more efficiently. Partly as a result, demand for hospital supplies has shrunk and suppliers have suffered.

A spirited debate is developing in the financial community about the risks and benefits of a huge influx of foreign capital, which has strengthened the dollar and helped finance the Reagan Administration's large budget deficits. In the last decade, foreign investment has at least quadrupled, helping to create jobs and financial opportunities and, to some extent, a stronger United States economy that encourages yet more foreign investment. A number of bankers and economists say that the enormous growth of foreign investment has weakened the national resolve to reduce the Federal deficit. They also fear that a sudden withdrawal could lead to a financial crisis.

MONDAY, APRIL 1, 1985 Companies Hospital Corp. and American Hospital Supply will merge in a deal that combines the largest hospital management company with the largest hospital supplier. The move is likely to spark other combinations in the $400 billion-a-year health-care industry and the companies said it could help lower hospital costs. The combined company would be valued at $6.6 billion. (Page A1.)

Still unable to agree on a budget for the fiscal year that starts at 12:01 A.M. Monday, state officials narrowed their differences tonight and arranged to use Federal funds for welfare and Medicaid advances to local governments. Use of the Federal funds would avoid a delay in almost $90 million in payments to local governments that are counting on getting the money Monday. A late-evening meeting between Governor Cuomo and legislative leaders ended with predictions that Monday might bring a belated start on voting on the $39 billion budget. 'Some Odds and Ends' ''Just some odds and ends out there,'' said Warren M. Anderson of Binghamton, the majority leader of the Republican-controlled State Senate, when he stepped into the the corridor outside the Governor's door.