(October 13, 2016, 1:15 PM EDT) -- ALEXANDRIA, Va. — In several petitions for inter partes review filed with the Patent Trial and Appeal Board on Oct. 11, Apple Inc. attacked the validity of a patent covering digital emulation (Petition for Inter Partes Review of U.S. patent No. 6,470,399, No. IPR2016-01839, PTAB)....