Siemens AG, which has a 12% holding in the Sunnyvale chipmaker, is to join forces with Advanced Micro Devices Inc in development and marketing of a family of integrated services digital networking chips. The family will include 15 parts, most of them from Siemens, but AMD will add data communications and networking interface chips. The two companies already distribute each other’s chips and both are official second-sources for Intel Corp microprocessors – but Advanced Micro is in a bitter dispute with Intel after failing to get masks for the 80386. It has gone ahead with a 16MHz version of the 80286 where Intel wanted the fastest version to be clocked at 12MHz, and each company has accused the other of violating their second-source agreement. Siemens has not been given masks for the 80386 either.