What was going on when I was born?

A House-Senate conference committee tonight approved a compromise military budget that Congressional aides said would restore money for all the 22 weapon systems that either the House or the Senate had voted to kill. The $302.5 billion military programs bill, which increases spending ceilings to make up for inflation, assures that no weapon program the Pentagon requested will be eliminated next year. One aide closely involved in the process said the bill for the 1986 fiscal year, which begins Oct. 1, ''proved once again that Congress can't kill weapons systems any more than the Pentagon can.'' Seeking Alternate Cuts Instead of dropping programs, the conferees cut about $20 billion from the Pentagon's budget request by slowing the pace of the production of some weapons, estimating lower costs for others, forecasting lower inflation and higher dividends from foreign currency exchanges and trimming personnel and operating costs.

President Reagan's tax revision plan would generate about $25 billion less revenue than the current tax system over the next five years, according to an authoritative Congressional report released tonight. In a joint statement issued along with the report, Treasury Secretary James A. Baker 3d and the leaders of the Congressional tax-writing committees agreed that $25 billion over five years was a relatively small amount of money, less than 1 percent of the nearly $3 trillion in tax receipts that are anticipated between 1986 and 1990. But they also said that the Administration had promised to modify its proposals so they would be absolutely ''revenue neutral'' before Congress begins drafting tax legislation in the fall. With the Government facing budget deficits of more than $200 billion a year, Congress is clearly unwilling to tackle any tax measure that seems likely to worsen the problem.

The Federal Communications Commission today authorized three American companies to offer limited competition to Intelsat, the nonprofit group of 109 countries that operates the only worldwide satellite communications system. The three are International Satellite Inc., the PanAmerican Satellite Corporation and RCA American Communications Inc. It could be three years, however, before any of the companies has a system in the air and operating, commission officials said, although one of the three predicted a launching by next summer. Still, today's decision effectively ends American recognition of Intelsat's 20-year monopoly over international satellite communications.

After the fire, most of the tenants, scattered to welfare hotels and the already overcrowded residences of friends all over the city, assumed they would never set foot inside their apartments at 80 East 116th Street again. Many of them had been burned out of other buildings or knew people who had been. All the signs indicated that their six-story walk-up would become yet another abandoned building on a block of abandoned buildings in the heart of Spanish Harlem.

Friday DEBUT FOR PIANIST Her musicianship has already been hailed in Vienna and Warsaw, in London and Tokyo, but this weekend marks the New York debut of Mitsuko Uchida, a young Japanese pianist who will appear at the Mostly Mozart Festival tonight and tomorrow night. Conducted by David Zinman, the program will feature Mozart's Piano Concerto No. 21 in C (K. 467), known to some as the ''Elvira Madigan'' concerto; Haydn's Symphony No. 57 in D; Haydn's Cello Concerto in D, performed by Janos Starker; and Bizet's Symphony in C. The concerts will be held at 8 tonight and tomorrow at Avery Fisher Hall, but Miss Uchida and Mr. Starker will also give a pre-concert recital from 7 to 7:30 P.M. Tickets are $8 and $13. Information: 874-2424. ANTI-APARTHEID CONCERT Hunter College is the scene for a benefit concert tonight on behalf of South Africa's anti-apartheid movement. ''Music Against Apartheid'' will feature Noel Pointer, a jazz violinist; Roy Ayers, a vibraphonist, and Abdullah Ibrahim and Sathima, a South African musician and singer, respectively. The benefit is being presented by the New York Southern African Solidarity Coalition, an anti-apartheid group organized by American black lawyers, and all proceeds from the concert go to the African National Congress of South Africa and the Southern African Project of the National Conference of Black Lawyers. Tickets are $15. Hunter College is at 68th Street and Park Avenue. Information: 864-4000.

OPEC ministers wound up their four-day meeting here by agreeing today to a slight cut in some oil prices. But analysts said the move merely underscores the organization's lack of unity and waning influence. The agreement still leaves OPEC's prices higher than those in today's free market. By a vote of 10 to 3, the Organization of Petroleum Exporting Countries approved Saudi Arabia's demand for a 50-cent cut in the price of heavy crude, to $26 a barrel, and a 20-cent cut in the price of medium crude, to $27.20 a barrel.

The Crown Zellerbach Corporation officially ceded control of the company yesterday to Sir James Goldsmith, the British financier, after an eight-month battle for the forest and paper products company. Crown said that Sir James, who has gradually increased his stake in the company to 51.3 percent, would become chairman. The two sides also pledged to eliminate the ''distractive atmosphere'' around the company, which is based in San Francisco. William T. Creson will give up the title of chairman but will remain president and chief executive. Roland A. E. Franklin, a close business associate of Sir James, will serve as vice chairman.

''The South African Government must move away promptly from apartheid, which we find to be repugnant and which is a basic cause of the violence South Africa is witnessing today.

International Washington urged Pretoria to hold talks with the black leadership in South Africa and expressed concern about the deteriorating situation there. [Page A1, Column 3.] 792 South Africans are being held with no legal rights under the new emergency regulations, Pretoria announced. It said the tally of deaths since the emergency began last weekend stood at 15. The figures seemed to cloak the sadness experienced by many black families. [A1:3-4.]

This week's announcement by the Toyota Motor Corporation of Japan that it would build an automobile factory in the United States marks the development of an important new phase in the often turbulent economic relations between the two countries, according to Japanese officials and economists here. In a little more than a year, Japan has risen to the front rank of foreign owners of American industry, along with Britain, Canada, West Germany and the Netherlands. With the surge in investment, a country that has been most conspicuous, and often berated, for the goods it ships to the United States is now becoming conspicuous as well for the goods it makes in this country. Rise in Direct Investment Last year, according to the Commerce Department, Japanese companies and their affiliates in the United States poured $1.7 billion into American businesses in so-called direct investment, more than three times the average of $490 million annually that the country had spent over the preceding five years. Direct investment includes outright ownership of American factories or the ownership of 10 percent or more of an American enterprise.

Competition in launching spacecraft is spreading worldwide, beyond the United States and the Soviet Union, as other nations and several private companies seek to stake a claim in what is being viewed as possibly the next economic frontier. The United States, as a result, is under pressure to protect its economic and technological leadership in space by reassessing the space shuttle's pricing policy, promoting greater private investment in space-related goods and services and forging a long-term space policy to assure a competitive edge, according to Government and aerospace industry officials and a new Congressional study. The European Space Agency, a consortium of 11 Western European governments, broke the American monopoly in launching services for the West with its successful Ariane rocket program. Arianespace, a corporation owned by the French Government and European banks and aerospace companies, is aggressively pursuing customers for Ariane's services and has won several contracts that would otherwise have gone to American conventional rockets or the space shuttle.

An obituary on Wednesday of Dr. Richard M. Emberson, a former executive director of the Institute of Electrical and Electronics Engineers, listed his survivors incompletely. They include his wife, Virginia.