What was going on when I was born?

President Reagan's chief tax-policy advisers and the members of Congress most closely involved in writing tax legislation agree that the House of Representatives will quite likely pass legislation this fall embracing the main principles of the President's plan to redesign the Federal income tax system. The measure, they are confident, would reduce tax rates for individuals and corporations, increase the personal exemption allowed taxpayers and their dependents, abolish many deductions and credits and, based on the best available estimates, raise neither more nor less revenue than the present tax law. Beyond that, there is no consensus among the more than a dozen key players interviewed last week on what will happen. Some people think the particular elements of the House bill - the rate structure and the specific deductions to be retained and repealed, for example - will closely resemble the President's proposals. Others think the bill will be vastly different from what Mr. Reagan recommended.

WELL, yes, there's this squabble about money for the rookies, agents insisting on more and club owners holding the line. But as the National Football League begins its 66th season this week, with the first training camps opening, most of the bigger headaches are still a year away. By this time next year, preparations will have begun for negotiations on the next series of contracts with ABC, NBC and CBS and for the next collective bargaining agreement with the players' union. Those two items, through which the 28 clubs will receive and pay out vast sums of money, will shape the football industry for years to come. Until then, the N.F.L. is expecting a season of serenity, give or take a few holdouts, with high expectations based on the United States Football League's yearlong hiatus, an influx of quality players from the draft and other leagues, a streamlined game and the emergence of several new powers among the clubs.

If the Landmarks Preservation Commission agrees, before long there will be a 19-story apartment tower squeezed behind the facades of a trio of old brownstones on East 79th Street just off Park Avenue. The brownstone fronts will remain, essentially as false fronts behind which the new tower will rise. If this unusual hybrid building goes ahead, however, it may not be the only such structure in New York: the commission has already given its nod to a much larger, but essentially similar, building, a 57-story tower designed to slip behind the facades of the landmark Rizzoli and Coty buildings on Fifth Avenue between 55th and 56th Streets. The two buildings were both planned by distinguished architectural firms -Conklin Rossant at 79th Street and Kohn Pederson Fox at Fifth Avenue. Though neither is ideal, both designs follow the current fashion of integrating distinct historical elements into a larger whole, and they are both among the more sophisticated essays in this eclectic style.

A diagram in some copies yesterday accompanying a description of President Reagan's surgery failed to show the full extent of the section of bowel removed. In the procedure, a right hemicolectomy, approximately two feet of bowel were removed, beginning with part of the transverse colon and continuing along the entire ascending colon, plus the cecum of the colon and part of the adjoining section of the small intestine called the ileum.

President Reagan's doctors said today that he was making a spectacular recovery from surgery and White House officials prepared for a long convalescence period in which he will carry a light work load. Mr. Reagan greeted White House aides a day after undergoing major abdominal surgery by telling them, ''I'm amazed at how good I feel,'' said Larry Speakes, the White House spokesman. Mr. Speakes said that Mr. Reagan's vital signs ''were good'' throughout the day. The President spent part of the day sitting up for about 45 minutes, reading a Western novel and watching television with his wife, Nancy, who arrived at the hospital at about 10 A.M. He also took a brief walk around his room, Mr. Speakes said.

''I'm amazed at how good I feel.'' - President Reagan, recovering from surgery. [A1:6.]

Kathy Baker, who said she did not particularly like golf a few years ago, won the 40th United States Women's Open championship today by three shots over Judy Clark as the pressure of the final round took its toll on the more experienced players. The 24-year-old Miss Baker achieved her first victory since turning professional two years ago by shooting a two-under-par 70 for a winning total of eight-under 280. None of her closest rivals broke par in this final round on the 6,274-yard Upper Course at Baltusrol Golf Club. Miss Clark was the only player among those in a position to challenge who shot par 72. That gave her a five-under 283 for runner-up. Miss Clark is still looking for her first victory after eight years on the professional tour.

New York City retail sales in June fell slightly under the year-earlier level, continuing a yearlong slump that has dismayed merchants. Seven of the city's largest retailers had an average decline of three-tenths of 1 percent compared with their sales of June 1984, according to a spot-check over the weekend. Sales of the metropolitan area stores, including those in the city and in their suburban branches, rose 2 percent in June over the same month in 1984, the spot-check found.

The State Department is examining a list of about a dozen Palestinians from which about four would be selected for inclusion in a Jordanian-Palestinian delegation that would hold talks with the United States this summer, department officials said today. Officials said the list of Palestinian candidates was secretly conveyed to Washington in the last 48 hours by King Hussein of Jordan, who received it from Yasir Arafat, the Palestine Liberation Organization leader. Officials, who declined to divulge the names on the list, said that none of them appeared to be prominent but that some were known to American experts on the Middle East. According to an understanding reached in May, none of these Palestinians are supposed to be members of the P.L.O., but the list could include members of the Palestine National Council, which functions as a sort of parliament for the P.L.O. A First Step Three-way talks between Jordan, Palestinians and the United States are designed to be a first step toward direct peace talks between a Jordanian-Palestinian group and Israel. Richard W. Murphy, Assistant Secretary of State for Near Eastern and South Asian affairs, is to lead the American delegation once the details are worked out.

American electronics companies are increasingly selling or licensing computer chip technology to Korean electronic companies, helping those companies rapidly advance in the semiconductor industry, executives and analysts say. The growing number of ties is seen as part of a new alliance of American and Korean companies against Japanese ones, which already dominate certain parts of the business of supplying the integrated circuits used in computers and other electronic equipment. But there is also a growing concern that the transfer of technology to the Koreans will create another competitor that could one day hurt the American industry. The Japanese, analysts point out, also made major strides by licensing United States technology. 'Trading Away Our Future' ''There are people who view it as trading away our future,'' said Lane Mason, a semiconductor industry analyst at Dataquest, a market research concern in San Jose, Calif.

In the ''California Corridor,'' the 350-mile stretch between Los Angeles and San Francisco that forms the nation's busiest air route, Aircal Inc. is waging a slick, multimillion-dollar marketing war against Pacific Southwest Airlines Inc. for the No. 1 position. Aircal Inc., a regional airline that draws about 70 percent of its revenue from the Los Angeles-San Francisco market, hopes to win over a majority of the 6.6 million travelers who each year fly between the four Los Angeles-area airports and the San Francisco Bay area's three airports. After three strained years, aggravated by fare cutting, that threatened to bankrupt the Newport Beach-based carrier, Aircal returned to stable prices and profitability last year. Since then it has poured millions into new Boeing 737-300 jets and a barrage of advertising aimed at unseating its rival. The company has signed a contract to lease 12 jets valued at $300 million, and it has options for 11 more.

After an unbroken two-month stretch of stability, the calm in the foreign-exchange market has been shaken, with the dollar's value declining sharply and the markets suddenly turning volatile over the past two weeks. The dollar is at its lowest level in about 10 months. Economists and currency traders say the dollar's drop is the result of an erosion of a principal factor behind its rise to record highs earlier this year: confidence in the Reagan Administration and its handling of the American economy. Undercutting the dollar are the increasing number of signs showing economic weakness and concern that the Government may not have ready solutions for the economy's problems, the analysts said. They added that these factors could provide the combination needed to sustain a decline in the dollar, finally breaking a five-year run.