What was going on when I was born?

Evelin, 19 years old, sat on the porch of her adobe shack, one of a handful in this tiny hamlet in the grassy hills of central El Salvador. Guiliguiste, so remote that it is reachable only by walking for an hour and a half from the nearest town, has a population of perhaps 50 people. All of them support the rebels fighting to overthrow the United States-backed Government. ''Here there are only supporters,'' said Evelin. who was eating sorghum seeds that were in a cup of chile water. ''There are no longer people who are of the other tendency. They left.''

Markets Bond prices surged as demand from domestic and foreign investors was more than enough to absorb the $16.75 billion of Treasury notes and bonds sold this week. The outlook for lower interest rates was also enhanced after the Federal Reserve said there was a surprisingly large $2.6 billion decline in the nation's basic money supply for the week ended July 30. (Page D1.) Stocks resumed their rally after a three-day lull , fueled by sharply falling interest rates paid on bonds. Hectic late afternoon trading pushed the Dow Jones industrial average up 27.94 points, to 1,224.05. Volume on the Big Board expanded to 131.2 million, up from Wednesday's 121.2 million shares. (D1.)

A brief article yesterday about a symposium on abstract painting and sculpture at the Whitney Museum of American Art gave incorrect dates for the symposium and for the closing of a related exhibition, ''Abstract Painting and Sculpture in America 1927-44.'' The symposium is Sept. 8; the exhibition closes Sept. 9.

Friday CAROUSEL' AT N.Y.U. ''Carousel,'' the 1945 Rodgers and Hammerstein musical about a factory worker, Julie Jordan, who falls in love with a carousel barker, Billy Bigelow, will be performed by the New York University Summer Musical Theater tonight in its final performance of the season. Richard Rodgers once said that the story was his favorite of all his shows, and critics have said that its adventurousness has made it seem less dated, perhaps, than any other Rodgers musical. It begins at 8 in the University Theater, a 350-seat air-conditioned auditorium at 35 West Fourth Street, southeast corner of Washington Square. Seats are $6; $5 for students or the elderly. The box office is open today from 10 A.M. to 6 P.M. Ticket availability: 598-3067. PIER'S BRAZILIAN FINALE Thiago de Mello and his band, Amazon, will play an evening of Brazilian jazz under the stars at a free concert tonight on Pier 16 at the South Street Seaport, where Fulton Street meets the East River. The concert, which begins at 8, is the last in the Seaport's fifth summer season. Tickets are distributed from the box office begining at 6 P.M. A line forms earlier. It's a good idea to bring something to sit on, as the pier is made of wood; smoking is not allowed, for the same reason. Information: 669-9400. BUSY CANADIAN BRASS

An article yesterday about four benefit concerts for the New Music Distribution Service, a promoter and distributor of contemporary-music recordings, gave an incorrect date. The concerts, in two auditoriums at the Public Theater, will be at at 4 and 8:30 P.M. on Aug. 26.

Trilogy Ltd., which gave up on its effort to produce a super computer last June, said today that it had abandoned its plans to design, build and market a high-speed ''wafer-scale'' computer chip. Gene M. Amdahl, Trilogy's chairman, said the company would instead attempt to design and assemble circuit packages for computer manufacturers from conventional semiconductors. The decision to drop the wafer- scale chips, which aimed at packaging circuitry on one larger chip to equal the power of 100 smaller chips and thus speed data processing, was not entirely a surprise. In June, a few days after it dropped plans for an innovative mainframe computer, Trilogy said it would not be able to bring the new wafer chips to market until at least 1986.

Malaysia, a predominantly Moslem country, has asked the New York Philharmonic to replace a work by a Jewish composer on a concert program there. The orchestra has agreed to comply. According to United Press International, Rais Yatim, Malaysia's Minister of Information, cited a Government policy against the ''screening, portrayal or musical presentation of works of Jewish origin.'' The work Malaysia objected to is Ernest Bloch's ''Schelomo,'' subtitled ''A Hebrew Rhapsody for Cello and Orchestra,'' which was scheduled to be performed Sept. 3 in Kuala Lumpur.

Once a year, the United Parcel Service truck arrives at a small storefront on Main Street with a package from the United States Government to the tiny Cayuga Indian tribe. Inside is a stack of muslin cloth, a continuing, annual payment for a treaty signed with the Cayuga Nation nearly 200 years ago. ''That's all that's come of it, muslin cloth,'' said Kate John, a Cayuga. ''A yard and a half each,'' Pauline LeRoy said. ''The only tangible thing,'' Jackie Meskimen said.

Daley Thompson, an emotional and uninhibited Briton, won the decathlon gold medal tonight in the Games of the XXIII Olympiad, just as he did in 1980 in Moscow. But he fell a tenth of a second short of matching the world record of the archrival who had taken the record from him. Had Thompson run the final race, the 1,500 meters, in 4 minutes 34.8 seconds or faster, he would have set a world record of at least 8,800 points. Had he run 4:34.9, he would have equaled the record of 8,798. Instead, he ran 4:35.0, to reach a total of 8,797 points. That gave the 26-year-old Thompson an Olympic record for the 10 running, jumping and throwing events over two days. He won comfortably from 6-foot-7-inch J"urgen Hingsen of West Germany, who scored 8,673 points. Siegfried Wentz of West Germany won the bronze medal with 8,412.

After a three-day lull, the stock market surged upward again yesterday. Traders, spurred by share prices that appeared to be holding steady and falling interest rates paid on bonds, poured into the market and drove the Dow Jones industrial average up 27.94 points, to close at 1,224.05. The gain came in hectic afternoon trading after a lackluster morning that saw the Dow down 5 points. The big push came when rates on United States Government securities, including yields on a new issue of 30-year Treasury bonds, started to fall, and a trickle of buying turned into a torrent.

Bond prices rose sharply yesterday, as demand from securities dealers and investors was more than enough to absorb the $16.75 billion of Treasury notes and bonds sold this week, including yesterday's $4.75 billion auction of new 30-year bonds. In contrast with other Treasury financings during the past year, which required increased interest rates to attract investors, this week's financings were completed amid declining yields for notes and bonds. Yesterday's strong rally, when bond prices rose 1 3/4 points, lifted prices and reduced yields of all three new Treasury issues. Securities dealers, many of whom have been worried that investor demand would dissipate as yields declined, said buyers continued to step forward during the past week, despite falling yields. Foreign investors - encouraged by new United States regulations allowing them to buy the new Treausry issues without paying any withholding tax - were a new source of demand augmenting the already strong demand from domestic investors.

By Therman White's reckoning, three or four visitors a day make their way to this tiny crossroad, past the overgrown pastures and tumbledown houses, in search of the vacant lot where the citizens of Alabama have raised a lonely granite monument to the memory of a native son named Jesse Owens. ''Every day there'll be a few folks who come by to see the place where the great Jesse Owens was born,'' says Mr. White, who likes to come out to chat with the visitors who stop at the five- foot marker at the center of this remote, mostly black, rural community. ''The site is not much right now, but we're fixing it up.'' he said. ''The people will come eventually.''