What was going on when I was born?

An off-duty correction officer described today how he captured Kathy Boudin at a roadblock after last year's Brink's robbery and murders in Rockland County, and how she told him that others did the shooting. The officer, Michael Koch, said he heard shots and saw Miss Boudin running across from him on the shoulder of the Gov. Thomas E. Dewey Thruway. ''I grabbed her and she said: 'I didn't shoot him, he did. He shot him, I didn't shoot him.' '' The person who did the shooting was not otherwise identified.

Trading accusations of opportunism, Lieut. Gov. Mario M. Cuomo and Mayor Koch yesterday held their final debate before Democratic voters nominate one of them for Governor. ''Before he was caught up by political temptation,'' said Mr. Cuomo, with a curt nod toward his opponent, Mr. Koch admitted he ''has not done the job in New York.'' The Mayor in turn accused Mr. Cuomo, who will be on the Liberal Party line in the general election, of looking for an excuse ''not to abide by the primary'' and support the winner. ''I happen to be the candidate who will win the primary,'' Mr. Koch said. Then, turning to Mr. Cuomo, he asked, ''Is your ambition more important than having a Democratic Governor?''

The people who live in the 12-story red-brick building at 62-64 Seventh Avenue here talk freely of its squalor and perils. But the briefing is unnecessary, for the specter of this place is such that those who visit for the first time shrink at the sight of it. In a lobby of dark corners, an elevator waits. It too is lightless. The passengers, straddling a runnel of urine, make their ascent. The cab stops, the door opens, the hallway air is thick and fetid. Here, next to an apartment, is a sprawling mound of empty containers, meat scraps and rotting vegetables. Beyond the pile, the corridor floor is black and viscous, covered with years of detritus and neglect. Building 62-64 and nine others like it make up the Columbus Homes project, one of 26 complexes in Newark's stock of public housing.

Brazilians have always been frustrated by the habit some foreigners have of confusing this vast country with others on the continent, but the lament has now taken on a particular urgency in the financial community. With an economy highly dependent on continuing investor confidence from abroad, bankers, businessmen and Government leaders complain that the debt crises in Mexico and Argentina are seriously undermining Brazil's capacity to address its own balance of payments problems. They are making it their principal order of business to convince foreign lenders not to tighten the purse strings, that Brazil, the world's eighth-largest economy, deserves treatment that is distinct and more favorable. ''You know how people are always thinking that Buenos Aires is the capital of Brazil and so on,'' said Peter P. Schmid, the representative of Credit Suisse in Rio de Janeiro. ''Brazil right now is suffering from this generalization, and it is jeopardizing a selling and marketing effort that Brazil has conducted for years.''

Federal District Judge Joseph H. Young said today that he would probably not interfere with the Martin Marietta Corporation's plans to purchase a 50.3 percent controlling interest in the Bendix Corporation after midnight Wednesday at a price of nearly $900 million in cash. A few hours after Judge Young's statement, Bendix announced that it had postponed until Monday a special stockholders meeting called to seek shareholder approval of two antitakeover amendments to Bendix's charter. The meeting had been scheduled for Wednesday morning. Bendix apparently postponed it in an effort to convince Marietta to delay its purchase of a controlling interest in Bendix until after the vote on the amendments, which could hamper the Marietta takeover. Executives of both companies met for several hours in what sources said may be an attempt to work out an agreement. (Page D4.)

International Israel agreed to the return of the three-nation peace force to Beirut as proposed by President Reagan. At a five-hour meeting, Prime Minister Menachem Begin's Cabinet decided to accept the American, French and Italian peacekeeping force. But the ministers rejected a call by the parliamentary opposition to set up an independent commission of inquiry into the massacre of Palestinians by Christian militiamen. (Page A1, Column 6.) The new President-elect of Lebanon is Amin Gemayel, a 40-year-old Maronite Christian. He was elected by a nearly unanimous vote of Parliament in an unusual display of Christian and Moslem unity. Mr. Gemayel replaces his brother, Bashir, who was chosen by Parliament Aug. 23 and killed in a bomb explosion Sept. 14. (A1:4-5.)

The Senate, at President Reagan's request, adopted a resolution tonight directing locomotive engineers to end the three-day strike that has interrupted commuter, freight, and passenger services in most sections of the country. Action by the House on a strike-ending resolution was expected Wednesday. But the House Commerce Committee failed today to agree on a measure similar to the resolution passed by voice vote in the Senate, and some committee members seemed to favor ordering a further cooling-off period and further negotiations. That would halt the strike but leave the dispute unsettled.

A late buying surge sparked by falling interest rates sent the stock market ahead in a spirited advance yesterday as the Dow Jones industrial average jumped 18.49 points, to 934.79, its highest closing in more than a year. Trading was heavy. The rally, which came after investor uncertainty had driven down the Dow average in the three previous sessions, was reminiscent of the thundering price gains posted during the second half of August. Again, pension funds and other institutions were major buyers.

In a move that surprised Wall Street, the Xerox Corporation yesterday announced an agreement to acquire Crum & Forster, a leading property and casualty insurer, for $1.6 billion in cash and stock. The acquisition will mark the second major move by Xerox into the growing financial services area in the past three years. According to the announcement, Xerox - the copier, computer and office information systems manufacturer whose dominance has been eroded by competition from Japan -intends to buy Crum & Forster for $55 a share in cash or stock. Wall Street analysts had speculated that Sears, Roebuck & Company, the Transamerica Corporation or the American Can Company were the likely suitors. Yesterday Xerox shares fell 3 1/4 points, to 31 3/8, on the New York Stock Exchange.

The Israeli Cabinet decided today to accept President Reagan's proposal to send the three-nation peacekeeping force back to Beirut. But it rejected a call by the parliamentary opposition to establish an independent commission of inquiry into the Beirut massacre. Although the Reagan Administration demanded an immediate Israeli withdrawal from Beirut, the Israeli Government insisted that its troops would remain until leftist Moslem militiamen and Palestinians were disarmed and the Lebanese Army was ready to take over key positions in the capital. Prime Minister Menachem Begin, who presided over the five-hour Cabinet meeting, was reported to have opposed the naming of a judicial commission on the ground that it would give the appearance of Israeli involvement in the massacre. An Unavoidable Concession The Cabinet left open the possibility that it might agree to some kind of internal examination of the massacre, in which Lebanese Christian militiamen slaughtered hundreds of Palestinian men, women and children last week.

The Personal Computers column in Science Times yesterday gave an in- correct schedule for Computer Show- case Expo, the exhibition at the New York Coliseum. It will take place tomorrow, Friday and Saturday.

Both the verbal and mathematics scores on the Scholastic Aptitude Test rose this year for the first time in 19 years. It marked an upturn in what has become a leading barometer for measuring the condition of the nation's schools. ''The long-term decline in S.A.T. scores has been halted by the 1982 seniors,'' said George H. Hanford, president of the College Entrance Examination Board, which sponsors the testing program. ''This year's rise, however slight, combined with last year's holding steady, is a welcome sign for educators, parents and students that serious efforts by the nation's schools and their students to improve the quality of education are taking effect,'' Mr. Hanford said in a statement issued in connection with the announcement of the 1982 results.