What was going on when I was born?

The surprise decision by the International Business Machines Corporation to drop its PCjr again raises the question that has plagued the home computer business since its inception: Where is the market for such machines? As recently as Christmas, the industry thought it had found the answer. The market, all agreed, was moving away from $200 machines, such as the Commodore 64, to more useful machines selling for roughly $1,000, such as the Apple II and the PCjr. Now, the promised land seems to be a mirage. Even giant I.B.M. has indicated it does not want to try to make a go of it right now, and Apple Computer Inc.'s sales are sagging, forcing the company to close its factories for a week to reduce inventories.

Victor Posner, the Miami businessman, dropped a long-smoldering takeover attack against the National Can Corporation yesterday, and said he would sell his stock in the company to Triangle Industries for nearly $150 million in cash. In a prepared statement, Mr. Posner said he would sell the stock to Triangle under that company's $41- a-share offer for National Can's 10.2 million shares outstanding. He said, however, that if someone else outbid Triangle, he retained the right to sell his stock to the high bidder. Mr. Posner, who owns 38 percent of the National Can stock, did not say what he would do with the $150 million, but Wall Street traders thought the money might be used to bail out the Sharon Steel Corporation.

Consumer spending advanced at a healthy rate in February, but personal income rose at the slowest pace in nine months, the Commerce Department said today. Personal income rose only three- tenths of 1 percent, just half of the increase in January. Analysts said that some of the weakness in February was the result of bad weather, which forced plant shutdowns.

An article in Business Day on March 2 about computers in courtrooms misstated the net income of the Barondata company for the first nine months of 1983. It was $952,000.

It was the morning of the first day of spring, an occasion George T. Delacorte, the 91-year-old philanthropist, celebrated with a walk through Central Park and a visit to his own beloved Alice. Mr. Delacorte's Alice is, of course, the bronze Alice in Wonderland statue that he presented to the city 26 years ago and that has belonged ever since to all children who make the pilgrimage. ''I picked the finest spot in Central Park,'' he boasted as the back of Alice's head, her long hair shining in the sun, came into view at the north end of the Conservatory Pond, under a just-budding willow tree. ''I told the mayor if he didn't want it there I wouldn't do it.'' Alice was built as a memorial to Mr. Delacorte's late first wife, Margarita, who liked to read Alice in Wonderland aloud to the couple's six children. Mr. Delacorte's face lighted up yesterday at the sight of several children clambering up the steps he had built just for that purpose and onto Alice's lap. A nanny introduced a 4-month-old blond boy, and Mr. Delacorte offered his hand. ''Hi, Eric,'' he said amiably.

Rupert Murdoch, the Australian publisher who has bought up numerous American newspapers and magazines, entered the motion picture business yesterday with an agreement to buy 50 percent of the 20th Century-Fox Film Corporation. Fox, now privately owned by Marvin Davis, a wealthy oilman, is one of Hollywood's best-known movie studios, but one that has suffered financial difficulties from a string of box-office disappointments. ''They need the capital to get back on track with production,'' said Harold Vogel, an analyst at Merrill Lynch, Pierce, Fenner & Smith Inc. ''It's been a rough period for them for the past one and a half or two years.'' The purchase surprised the Hollywood community, and raised questions about what effect it might have on the kind of films the studio produces.

In an effort to calm financial markets, Paul A. Volcker, chairman of the Federal Reserve, said today that it was prepared to lend funds to 70 Ohio savings and loan associations closed last week. Mr. Volcker's assurance of assistance, his first public comments since the thrift crisis began last week in Ohio, came a day after the dollar plunged and gold prices soared almost $36 an ounce on fears of the effect of the events in Ohio. ''We are working with the Ohio authorities on the situation,'' Mr. Volcker said, ''and we will be prepared to lend to them as they are deemed to be in strong enough condition to reopen.'' Ohio Action Noted Mr. Volcker noted that the Ohio Legislature had passed emergency legislation early this morning that would permit the thrift institutions to reopen, provided they had Federal deposit insurance. ''And the job now is to get the institutions opened rapidly and in an orderly fashion so that we don't have a repetition of the situation,'' he said.

The Sports of The Times column on March 7 incorrectly described the base hit on which Enos Slaughter of St. Louis scored the winning run of the 1946 World Series. It was officially scored a double.

A report in the Financial Briefs column in Business Day Monday about a debt offering by Hercules Inc. misstated the offering's size. It is 50 million principal amount of European Currency Units, which are a composite of the currencies of the 10 members of the European Economic Community.

The Vatican today condemned the teachings of a Brazilian exponent of liberation theology, saying the theologian's views endangered ''the healthy doctrine of the faith.'' In an 11-page document, the Congregation for the Doctrine of the Faith said the Rev. Leonardo Boff's sharp critique of the hierarchical structure of the Roman Catholic Church could lead ''to the destruction of the authentic sense of the sacraments and of the word of faith.'' Father Boff, a Franciscan priest, could suffer church sanctions should he refuse to alter his teachings, but a Vatican official said it was too early to speculate on the outcome of the case. 'No Threat,' Official Says ''There's no threat, hidden or implied, in the document,'' the official said. The theology of liberation, a body of teachings that is popular in Latin America, often draws on Marxist analysis in emphasizing the church's special commitment to the poor.

The accountant who audited the books of the defunct E.S.M. Government Securities Inc. was charged today by the Securities and Exchange Commission with knowingly filing false and misleading auditing reports and with receiving secret payments from E.S.M. officers totaling $125,000. A Federal judge in the Southern District of Florida issued a temporary restraining order against Jose L. Gomez, a managing partner in the Fort Lauderdale, Fla., offices of Alexander Grant & Company, the nation's 11th-largest accounting firm, enjoining him from any further commission of such acts. The judge, Jose A. Gonzalez Jr. of Miami, also froze all of Mr. Gomez's assets and ordered him to give an accounting by next Tuesday of all payments he has received since 1977 from any of E.S.M.'s four companies and their officers. Today's action is the latest twist in a complex financial debacle that began with the March 1 closing of E.S.M., a securities firm based in Fort Lauderdale. The closing led in short order to the collapse of an Ohio savings and loan. That collapse, in turn, touched off a banking panic in Ohio, which has forced the closing of 71 thrift institutions there and sent tremors through national and international financial markets.

The Union Carbide Corporation said today that the chemical accident at its pesticide plant in Bhopal, India, in December stemmed from a variety of operating errors and procedural violations that would never be tolerated at the company's similar plant in the United States. In announcing the long-awaited results of its investigation of the tragedy, Union Carbide said it appeared that the Excerpts from reports, page D22. deadly reaction occurred when a large amount of water entered one of three storage tanks containing methyl isocyanate, an ingredient in making pesticide. But without six or more errors and violations, company officials said, the entry of water would not by itself have had so drastic a result. Union Carbide officials also said that the plant in Institute, W.Va., had more safeguards and proper operation and thus was justified in reopening shortly, perhaps during the first week in April. The West Virginia plant has been closed since the Dec. 3 disaster in Bhopal, in which at least 2,000 people died and 200,000 were injured in the worst industrial accident in history.