July 24, 1985

The Mexican Government, reversing an earlier decision, said tonight that it would permit the International Business Machines Corporation to build a plant, which the company would wholly own, to produce microcomputers here. The agreement came after the computer maker agreed to sharply increase its capital investment in the plant to $91 million, from $6.6 million, over the next five years. I.B.M. also made commitments regarding the pricing of the computers, the extent to which parts would be produced in Mexico, the volume of exports and the import of technology. Negotiations on these issues have been in progress since the Government rejected an earlier proposal in January.

Orders for durable goods, buoyed by continued demand for military equipment, rose 1.8 percent in June, the third consecutive monthly increase, the Government reported today. The gain, which had not been generally expected, gave rise to cautious optimism about the economy in coming months after a year of sluggish activity in the industrial sector. The Commerce Department said orders for durable goods, items expected to last three or more years, rose to $104.9 billion in June following advances of 3.3 percent in May and two-tenths of 1 percent in April.

Late last night, as wind and rain from a tropical storm swept the puddled streets of Key West, jubilant treasure hunters and investors sang rousing choruses of ''We're in the Money'' and ''The Impossible Dream,'' pounded out by a piano player in the Two Friends bar. Besides yielding riches of silver and gold that had been buried in the ocean floor for more than three centuries, the sunken Spanish royal galleon they discovered last weekend may prove to be a scientific bonanza, their chief archaeologist said today. ''It's a virgin shipwreck in situ, one of the greatest treasure finds from an ancient shipwreck recorded anywhere,'' said Duncan Mathewson, chief archeologist for Treasure Salvors Inc. of Key West. Backers of the limited partnership spent years and millions of dollars to search hundreds of square miles of sea bottom 40 miles west of here for the remains of Nuestra Senora de Atocha, the 550-ton flagship of a Spanish treasure fleet sunk in a hurricane in 1622. On Saturday, working 54 feet under the choppy, bottle-green surface, divers found the prize. Powerful gusts of water pumped down from their ship blew up a storm of sand and exposed a jumbled mound of hundreds of silver bars, each 15 inches in length, that weighed 70 pounds each. Nearby gold and silver coins and jewels spilled from a well-preserved cedar treasure chest.

ONE of America's most renowned chefs, Paul Prudhomme of K-Paul's Louisiana Kitchen in New Orleans, gave a festive party at a Columbus Avenue restaurant Monday night to announce his arrival in New York for a five-week stay, only to be told by city health inspectors yesterday afternoon to close the premises. Mr. Prudhomme opened his roadshow version of K-Paul's yesterday anyway. ''We are not endangering anyone's health,'' he said shortly before opening. ''Our food is good and it's clean. The violations we were cited for were grossly unfair.'' When Marvin Bogner, an assistant health commissioner, was told yesterday evening that the restaurant, also known as K-Paul's, was being opened, he said that because no health inspectors were available, the department could not prevent the opening. But he said inspectors would be at the restaurant today to close it again.

Marvin L. Warner, the principal owner of the failed Home State Savings Bank, received millions of dollars in payments through fictitious securities transactions from E.S.M. Government Securities Inc., the bankruptcy trustee for E.S.M. said today at an Ohio state legislative hearing. Burton M. Bongard, the former chairman of the Cincinnati-based thrift institution, also received large payments in similar transactions, the trustee said. The collapse of E.S.M. in March led to the failure of Home State, which had heavily invested with the firm for years, and touched off the temporary closing of 71 other Ohio thrift institutions in the most extensive bank holiday since the Depression. The hearing was disrupted at midmorning by the disclosure that Stephen W. Arky, Mr. Warner's son-in-law, had committed suicide in his South Miami home Monday morning. In the past, the E.S.M. trustee, Thomas Tew, had accused Mr. Arky of receiving unusual financial benefits from the government securities firm, which was based in Fort Lauderdale, Fla.