What was going on when I was born?

TUESDAY, JANUARY 8, 1985 Companies Diamond Shamrock called off a $3.3 billion merger with Occidental Petroleum only hours after the companies' managements had agreed to the deal. Analysts said they understood that Shamrock backed out because William H. Bricker, its chairman, would not have been kept on after the merger by Dr. Armand Hammer, Occidental's chairman. It was the biggest takeover canceled since Gulf backed out of a $5 billion deal to buy Cities Service more than two years ago. (Page A1.) News of the termination of the planned merger sent the shares of Diamond Shamrock plunging in late trading. Wall Street arbitragers were believed to be the big losers. (D5.) The Supreme Court agreed to hear a challenge to the regional banking zone that Connecticut and Massachusetts set up to prevent banks outside New England from merging with local banks. The case could affect the course of interstate banking mergers throughout the country. The Court also agreed to decide cases involving joint bank accounts and stock tips from brokers. (D1.)

John A. Zaccaro pleaded guilty yesterday in Manhattan to an indictment charging him with scheming to fraudulently obtain financing for a multimillion-dollar real-estate deal. The District Attorney said the scheme had been designed to net large commissions for Mr. Zaccaro and a partner. After the indictment on a single misdemeanor charge was read to Mr. Zaccaro in State Supreme Court, he pleaded guilty in an agreement under which he would not be sent to jail but would receive only up to the maximum $1,000 fine. The crime is punishable by up to a year in jail, plus the fine. The actions marked an end to a sensitive investigation that colored the 1984 Presidential election and the unsuccessful Democratic Vice-Presidential campaign of Mr. Zaccaro's wife, Geraldine A. Ferraro. But yesterday's conclusion left murky some key questions of responsibility for dealings that the prosecutors called fraudulent.

yes, these single-cell aquatic organisms have complete visual systems - biophysicists have discovered a striking family resemblance between algae and cows. They share the same kind of light-sensitive protein, rhodopsin, making it a rare vestige of the common evolutionary origins of plants and animals. The discovery of animal-like rhodopsin in algae promises to afford scientists a means of conducting laboratory experiments on the origin and nature of vision in animals, including humans. The rhodopsin in the human eye has been found to be closely related to the bovine molecules.

Mayor Koch proposed yesterday that many older, smaller apartment buildings be required to have intercoms and locked front doors, making the buildings more secure. He said he would increase the number of city housing inspectors to make sure all security measures were enforced. In a day of announcements focused on crime, the Mayor also repeated his support for several measures he has recommended without success before, saying he hoped to use the recent shootings of four youths on an IRT subway train as a catalyst for improving the criminal-justice system. 'Clarion of Alarm' ''We want to sound the clarion of alarm and focus all of the energy, attention, anger and frustration into getting changes,'' the Mayor said. He was alluding to the subway case and Bernhard Hugo Goetz, the 37-year-old New Yorker who has become a hero to many people in and out of the city since telling the police that he shot the four youths after they harassed him and asked him for money.

Administration officials said today that President Reagan would endorse a modified version of the Treasury's plan to overhaul the nation's tax system. They said the proposal would serve as a cornerstone for Mr. Reagan's State of the Union Message Feb. 6. Officials said he would adopt the basic philosophy of the Treasury's plan: to cut tax rates for individuals and corporations and to abolish many tax preferences. Final decisions on modifications had not been made, the officials said, but consideration was being given to changing the plan in regard to the tax treatment of depreciation, dividends, interest, capital gains, personal exemptions and charitable contributions. (Page D1.)

''There's a minimum wage of $3.35 an hour. You get it for frying hamburgers at McDonald's and you ought to get at least that much for dancing for the President.''