involved a literal emulator. However, none involved an emulator as we would understand the concept (as opposed to "interoperability" more generally). There was also the matter of the PC clones, where IBM's only litigation was against those who literally copied the BIOS, as opposed to those who made compatible hardware without IBM's permission
although conceivably IBM was concerned about antitrust issues there in choosing not to litigate over the non-BIOS-copying clones.
As other commenters pointed out, there are court decisions in favor of emulators in the post-DMCA environment (Connectix and Bleem), where DMCA claims were not raised at all in those specific cases.
These two cases applied pre-DMCA copyright law to the question of the legality of the emulation, but weren't actually pre-DMCA chronologically. I'll take that as a very helpful correction to the way I phrased the point.
https://en.wikipedia.org/wiki/Atari_Games_Corp._v._Nintendo_....
https://en.wikipedia.org/wiki/Sega_v._Accolade
https://en.wikipedia.org/wiki/Lewis_Galoob_Toys,_Inc._v._Nin....
involved a literal emulator. However, none involved an emulator as we would understand the concept (as opposed to "interoperability" more generally). There was also the matter of the PC clones, where IBM's only litigation was against those who literally copied the BIOS, as opposed to those who made compatible hardware without IBM's permission
https://en.wikipedia.org/wiki/IBM_PC_compatible
although conceivably IBM was concerned about antitrust issues there in choosing not to litigate over the non-BIOS-copying clones.
As other commenters pointed out, there are court decisions in favor of emulators in the post-DMCA environment (Connectix and Bleem), where DMCA claims were not raised at all in those specific cases.
https://en.wikipedia.org/wiki/Emulator#Legal_issues
These two cases applied pre-DMCA copyright law to the question of the legality of the emulation, but weren't actually pre-DMCA chronologically. I'll take that as a very helpful correction to the way I phrased the point.