DIGITAL Equipment Corp will provide a worldwide warranty for products made by President Technology Inc. DEC announced the strategic alliance with the Taiwan computer-maker at the weekend. PTI specialises in designing and producing monitors, PC motherboards, notebook PCs and personal computer products for export around the world. Through its 1,600 service centres in 110 countries, DEC would provide responsive, reliable services for PTI products, the companies said. The PTI president, James Liu, said the alliance would use PTI's resources effectively in line with its commitment to research and development into new products. ''We believe this alliance is beneficial to the company's healthy business development,'' he said. DEC said its network of service centres covered every country in which it did business.