Nintendo is at least attempting to secure a patent on an emulator for its legacy portable consoles, though it may be an act of prudence instead of a change of heart on its firm stance against bringing its titles to smartphones and tablets.
In the patent application, Nintendo details what a Game Boy emulator would bring to a world that's dominated by tablets and cell phones.
"While GAME BOY.RTM. platforms are inexpensive and have long battery life, there may be situations in which it would be desirable to play or use applications developed for GAME BOY.RTM. on other platforms," states the patent application (PDF). "For example, an airline, train or other vehicle passenger might want to play video games during a long journey."
Nintendo lists several optimizations it would bring to the emulator to ensure that the experience on smartphones and tablets is just as good as the games were on Game Boys. Bitmap blending techniques like BLITing and the remastering of text would help the games maintain their beauty when scaled up to tablets.
Along with coding in mechanisms to scale the beauty of the Game Boy ROMs to a variety of mobile devices, Nintendo is also concerned about the execution of the emulator on low-end mobile devices.
To prevent games from turning into a slide show, Nintendo mulls a frame and execution skipping mechanic. If the emulator was failing to deliver a solid frame rate, with would selectively drop frames and commands so that the games would still be playable.
"Unless the software emulator is carefully designed and carefully optimized, it will not be able to maintain real time speed performance when running on a slower or less highly capable processor," states the patent application. "Slow-downs in game performance are generally unacceptable if the average user can notice them since they immediately affect and degrade the fun and excitement of the game playing experience."
Other Game Boy emulators have been around for more than a decade and they do a solid job rendering virtual copies of the handheld console's games on smartphones and tablets. Nintendo's filing of a patent on a Game Boy emulator appears to be due diligence, as it clashes with beliefs expressed by Nintendo President Satoru Iwata on more than one occasion.
Back in January of 2014, Iwata indicated that porting Nintendo's games to Android and iOS hurt the long-term success of its handheld consoles.
"[We] believe that we cannot show our strength as an integrated hardware-software business in this field, and therefore it would difficult to continue the same scale of business in the medium- to long-term," stated Iwata.