What was going on when I was born?

The Federal Reserve Board today allowed the BankAmerica Corporation, which owns the nation's largest bank, to buy a major discount stockbrokerage firm. It thus set the stage for commercial banks to get directly into the stockbrokerage business and to own seats on stock exchanges, despite the provisions of the Glass-Steagall Act of 1933. That act prohibits commercial banks and securities firms from engaging in each other's business. The move followed a year of often-bitter hearings and debate over whether the Federal Reserve, which regulates bank-holding companies, should approve the BankAmerica Corporation's application to acquire Charles Schwab & Company, of San Francisco, the nation's largest discount brokerage firm.

President Reagan was portrayed by White House officials today as increasingly likely to accept modest cuts in military spending in his 1984 budget along with a freeze on spending for selected Government programs. They said the savings would be substantially more than the $30 billion in reductions agreed on within the Administration earlier this week. As described by several officials, the freeze might include suspension of cost-of-living increases in pay, retirement and benefit programs, including military pay and retirement. The freeze concept was reported today to have gained support from David A. Stockman, the budget director, as well as from Treasury Secretary Donald T. Regan and Martin S. Feldstein, the chairman of the Council of Economic Advisers.

One day after the United States Department of Energy said natural gas prices would continue to rise sharply, New York officials cautioned consumers about converting their home heating systems from oil to natural gas. On Thursday, the Energy Department said the price of natural gas used in home heating in the United States would rise 25 percent in the first three months of the year from the comparable period in 1982. The department said gas prices would reach $6.60 per thousand cubic feet by the end of 1983, up 150 percent from the $2.63 consumers were paying in 1978. ''Absolutely be very wary about conversion from oil to natural gas,'' said Karen S. Burstein, the executive director of New York State's Consumer Protection Board. ''It may still save money for some individuals, but the decision requires caution.''

The Soviet Union confirmed yesterday that Cosmos 1402, its nuclear-powered reconnaissance satellite, was falling out of space but said that measures had been taken to insure that radioactive components would burn up before reaching the earth. The announcement by Tass, the official Soviet press agency, said that on a command from the ground the five-ton satellite was split into separate fragments. This was done, according to an unofficial translation, ''with the goal of separating the active part of the reactor in order to insure the later, full combustion in the dense layers of the atmosphere.'' The United States, however, said that it was not fully reassured by the Soviet explanation and assessment of the satellite's troubled flight. Radar and tracking cameras indicated that the main body of the satellite, including the nuclear reactor and its enriched uranium fuel, appeared to remain intact. There was also some question as to how much control the Russians still had over the satellite.

Millions of gallons of gasoline continued to burn in huge fireballs here this morning, after explosions early Friday ripped through a storage-tank farm, killing one worker, injuring 24 people and sending out shock waves felt for 100 miles. One gigantic blast, which the police said shot flames 1,000 feet into the air, occurred at about 12:15 A.M. Friday, and shattered hundreds of windows in communities around the site. Calls Inundate the Police Residents throughout the New York metropolitan area, awakened by the thunderous explosion, scurried to check if something had happened in their own houses. Local police departments were inundated with telephone calls. Hundreds of onlookers, drawn to the scene of the spectacular blaze, caused confusion and blocked roads for emergency vehicles.

The nation's unemployment rate was 10.8 percent in December, almost unchanged from the revised 10.7 percent the month before, the Labor Department reported today. Today's figures showed the impact of a recession that is now the longest since World War II. The average unemployment rate for 1982 was 9.7 percent, the highest since 1941. For December, 12,036,000 people were out of work, up slightly from November and the most since 1933. There were 99,093,000 people working, down just slightly from November.

The Reagan Administration today lifted the five-year-old embargo on arms sales to Guatemala because of what it said were ''significant steps'' taken by the Government to end human rights abuses. The State Department announcement allows Guatemala to buy from the Defense Department $6.3 million worth of spare parts and other equipment for its air force, mostly to rehabilitate American-made helicopters for use against guerrillas. The move, while small in military terms, was viewed by the Administration and its critics as an important symbolic step signifying support for the Government of Gen. Efrain Rios Montt, who overthrew Gen. Romeo Lucas Garcia and seized power last March. 'Progress Has Been Made' Guatemala has been accused by the United States and many human rights groups of repressive tactics and rights violations. But Administration officials have reported an improvement in recent months.

The Government today named Mizuo Kuroda as its chief delegate to the United Nations. The Foreign Ministry said Mr. Kuroda, 63 years old, would succeed Masahiro Nisibori, who is returning to Tokyo for a new assignment. Mr. Kuroda has served as Japan's Ambassador to Yugoslavia, Egypt and Australia.

A 35-year-old Israeli soldier collapsed on seeing other soldiers blown apart while under heavy artillery bombardment. Evacuated to a treatment center, he sat and stared at one spot on the floor, responding only when someone touched him and called his name. He refused to touch a rifle. Another soldier spent 24 hours crying, yelling, rolling on the floor and crawling around, trying to piece together what he imagined were the parts of a friend's dismembered body.

Gunmen ambushed an Israeli military bus south of Beirut today, wounding 21 Israeli soldiers. The Israeli command in Tel Aviv said the gunmen fired small arms and bazookas at the bus two miles east of the village of Kfar Sil.

The United States expressed official concern to the Soviet Union today over confirmed intelligence reports that Syria is building sites to handle a long-range Soviet-made antiaircraft missile that American officials fear could provoke a new round of violence in the Middle East. Administration officials said American and Israeli intelligence had detected two construction sites inside Syria for SA-5 missiles, known in NATO terms as Gammon. In addition, one official said, the missiles are believed to be on Soviet ships bound for Syria. The new missiles, which have a range of 150 miles and an altitude of 95,000 feet, could not only protect Syrian airspace but also reach into the Mediterranean to threaten American carrier aircraft and pose threats to Israeli planes over Israel and Lebanon and to Jordanian aircraft in Jordan, officials said.

Seven members of the Danish Greenpeace organization were arrested today after chaining themselves to the entrance of the French Embassy here, the police said. The seven were protesting the seizure of the Greenpeace vessel Sirius in port at Cherbourg Thursday by French authorities, a spokesman for Greenpeace said. The Sirius was in Cherbourg to hinder the anticipated arrival of a Japanese vessel due to unload nuclear waste for recycling in France.