Virata Corp., a semiconductor and software supplier, agreed to buy closely held D2 Technologies Inc. for $90 million in stock. Santa Barbara-based D2 develops voice software used by global telecommunications equipment suppliers. Virata develops software that helps customers enhance products they already make, including modems for high-speed Internet access. Santa Clara, Calif.-based Virata will add D2's voice software to its existing digital subscriber-line products. Virata shares rose $2.25 to close at $41.25 on Nasdaq. They've almost tripled since the company's initial public offering in November.