The gradual opening of the once hermetically sealed Brazilian computer market has enabled AT&T Corp to gain a jump on its rivals by buying, through its AT&T Global Information Solutions Brasil Ltda, a stake of more than 80% in Sao Paulo personal computer manufacturer Monydata Ltd. AT&T says the acquisition will enable it to offer complete and integrated computer systems to Brazilian customers and gives it a three-year lead on its previous strategy for the Brazilian computer manufacturing market. It plans to use Monydata as a springboard into the territories of the four-country Mercosur free trade agreement. The amount paid was not revealed. Founded in 1984, Monydata reported sales of $45m for 1993.