Sperry and Microsistemas Micron S.A., Irapuato, Mexico, signed an agreement under which the Mexican firm will manufacture personal computers compatible with the Sperry PC . . . Shareholders of Amerada Hess approved new takeover defenses that would make it easier for the company’s chairman and board of directors to veto any attempt to oust the management of the oil company . . . Wheeling-Pittsburgh Steel, holding contract negotiations for the first time since its bankruptcy filing, asked the United Steelworkers to slash wages and benefits 29% to $15.20 per hour . . . McDonnell Douglas said it sold six MD-82 airliners to the South Korean government for about $150 million.