What was going on when I was born?

THE first thing that should be said about TriBeCa is that it is not SoHo. The two neighborhoods, which abut each other at Canal Street, can seem similar - they both contain residential lofts housed in some of the city's finest 19th-century industrial and commercial architecture; they have fashionable restaurants and, superficially at least, similar populations to fill them, and they both have a kind of grittiness to them that makes clear that, however strong the signs of prosperity, these places are not the Upper East Side. But there the similarity ends. TriBeCa, which roughly includes the blocks west of Broadway and south of Canal Street to Chambers Street (the name comes from the words TRiangle BElow CAnal), is a rich amalgam of architecture, much of it in masonry, where SoHo is essentially a unified composition of block after block of cast-iron fronts. TriBeCa is more diverse in its uses and its population than SoHo, too: there are fewer boutiques, fewer art galleries, and there is never the sense, as there is on a Saturday in SoHo, that the neighborhood belongs entirely to people who do not live in it.

The nation's major banks dropped the prime lending rate to 13 percent from 13 1/2 percent yesterday, a reaction to the continuing decline in the cost of money to the banks. The move was hailed as overdue by economists, some of whom predicted that there would be a further drop of perhaps a half-point in the benchmark rate. The prime rate is used by banks to calculate the interest rates to customers with top credit ratings. The interest rates for large corporations are generally below the prime rate, while loans to most small and medium-sized businesses are closely tied to it.

On the eve of a parliamentary session that is expected to outlaw the independent Solidarity union, the Polish Government has been seizing opposition activists and bracing itself for any flurry of demonstrations. The Government's prize catch - a sharp blow to the fugitive union leadership - is Wladyslaw Frasyniuk, the Silesian labor chief and one of the organizers of the union's five-man underground coordinating committee. Thus far, there has been no response from the Solidarity underground to the plans to enact the long-awaited trade union bill at the session of Parliament opening on Friday. An attempt was made Wednesday to broadcast a clandestine Solidarity message over the radio, but the signal was so weak that it could not be made out.

The financial markets rallied dramatically yesterday, fueled by hopes that interest rates would continue to decline.Stock market volume surged to a record level of 147.1 million shares and prices rose sharply. In the credit markets, interest rates tumbled and prices of Government notes and bonds soared. The dollar plummeted, while prices of gold and silver climbed. Most of the nation's major banks cut their prime rate, or what they charge their key corporate customers for loans, by half a percentage point, to 13 percent, the lowest rate in two years.

Warner Communications Inc., a media conglomerate, said yesterday that it had reached an agreement to buy the Madison Fund Inc., a New York-based investment managment company. Under the terms of the deal, Madison shareholders will exchange all their stock for Warner debentures and warrants, and Madison will become a wholly-owned subsidiary of Warner. Geoffrey W. Holmes, a Warner spokesman, said that Warner will then sell off the Madison Fund's assets - basically its stock portfolio - and use the proceeds in part to meet short-term debt obligations, which amount to ''over $500 million.'' Net Assets of $380 Million The Madison Fund, with a net asset value of $380 million, will in effect disappear. ''We are not going into the mutual fund business,'' Mr. Holmes said.

The United States and Western Europe are close to settling their 10-month trade dispute over steel, industry and government sources reported today. Under the arrangement, which still is subject to final approval by European and American producers, European governments would establish quotas to keep shipments at around 5 percent of the overall American market, a domestic industry official reported. Last year European steel products accounted for 6.3 percent of the United States steel market. Japan already informally limits steel shipments to the United States to about six million tons a year. Japan, Western Europe and the third world each have about a third of the import market in the United States, with imports, over all, claiming a 20 percent share of the American steel market

''A gold rush is what it is,'' Fred Caporizzo said as he took a break from his job as an electrician at a six-story office building rising here. ''Five years ago, we had nothing to do. Now anyone who wants a job can have one.'' While the nation endures the highest unemployment rate in more than 40 years, this city and its surrounding area in southwestern Connecticut are bustling. In July, when the national unemployment rate was 9.8 percent, the Stamford area's was 3.8, the lowest in the country. The nationwide figure for August will not be known until Friday, but it will certainly show Stamford's 3.5 percent for the month to be one of the lowest rates anywhere - and a level the nation as a whole has not seen since December 1969.

Using scat syllables and sounding at times more like instruments than human voices, the Swingle Singers, formed in the 1960's, used to focus on Baroque music. But the New Swingle Singers perform everything from Bach and Mozart to Gilbert and Sullivan and John Lennon and Paul McCartney. The vocal octet, which includes its founder, Ward Swingle, will be at the Top of the Gate, 160 Bleecker Street, tonight through next Friday. Peformances are at 8 and 10 tonight and tomorrow; 3 and 8 P.M., Sunday, and 8 P.M., Tuesday through Thursday. Tickets are $12.50 tonight and tomorrow; $10 other times. Information: 982-9292 or 473-7270. ART COMES TO THE GARDEN An exposition of emerging talent will fill the Rotunda of Madison Square Garden on Eighth Avenue and 31st Street over the Columbus Day weekend. Some 175 selected painters, sculptors, printmakers and photographers will have more than 1,500 works for sale in ''New Artists at Madison Square Garden.'' Today, 12:30 to 10 P.M.; tomorrow and Sunday, 11 A.M. to 10 P.M., and Monday, 11 A.M. to 8 P.M. Admission is $3.75.

WHEN the curtain rose on the dancing orphans of ''Annie'' on Wednesday, it marked the debut of the show's seventh Miss Hannigan, the mean matron of the orphanage who spends most of her waking hours trying to squelch her irrepressible charges. The new Miss Hannigan is hardly a novice, to be sure. She is June Havoc, the stage and screen veteran, who headlined as ''Dainty June, the Darling of Vaudeville'' at the age of 7 and has spent so many years in show business she refuses to count them anymore. Recent days have marked another major cast change on Broadway, although this one is temporary: for the last two weeks Diahann Carroll has been playing the psychiatrist in ''Agnes of God'' while Elizabeth Ashley, who returns next week, is on vacation. Some might be surprised that a ''name'' actress like Miss Havoc would accept a role already occupied by six predecessors, most of whom - like her immediate predecessor, Marcia Lewis - were less famous than she. Other theatergoers might be startled by the substitution of a black actress best known for musicals, television and nightclub work for a white actress in a harrowingly serious drama like ''Agnes of God.''

Stock prices rose sharply again and volume surged to a record of 147.1 million shares. The previous record, 137.3 million shares, was set Aug. 26. The Dow Jones industrial average rose 21.71 points, to 965.97. Economists observed that the two-day rally, unlike most bull markets, appears to be based on a belief not that the economy is recovering but that it is in such bad shape that the Federal Reserve Board will have to let interest rates decline. (Page A1.) Wall Street feels big volume may soon become routine. (D1.) The prime lending rate was cut by a half-point, to 13 percent, by the nation's leading banks. The move, led by Citibank, was welcomed by economists, some of whom predicted another half-point decline. Meanwhile, Chemical reduced its rates on loans for consumers with maturities of up to 60 months by 1.5 percentage points. (D1.)

THE exhibition called ''Arts of the Islamic Book'' at the Asia Society, 725 Park Avenue, at 70th Street, is of the highest and most varied curiosity. How could it be otherwise when the art in question ranges in time from the late 9th to the early 19th century and in place of origin from Kairouan in Tunisia to Cordoba and Seville in southern Spain, and from there all the way across to Turkey, Iran the Arab lands and the subcontinent of India? If we are not to be dazed and winded by so rapid a succession of changes, two things are needed, and both of them are amply present here. One is the cumulative exhilaration that comes about when we realize that everything on view is about as good as it could be. The other is a continuity of personal taste. If we feel that one particular person has been guided by his own inmost inclinations, rather than by a panel of experts, we are delighted to let him guide us - arm in arm, as it were - from one age, one place and one intellectual and emotional climate to another.

The Beirut Bourse reopened today after being closed for four months because of the Israeli intervention in Lebanon. The president of the brokers association, Nabil Aoun, told a news conference that most share prices rose in today's trading by about 50 percent from the levels at the last session, on June 6. Mr. Aoun said that this was because of renewed business confidence after the end of full-scale fighting and the election of a new Lebanese president.