It appears as if Sony may be tinkering with the idea of putting PlayStation 2 backward compatibility back into the PlayStation 3. As reported by Siliconera, the publisher has filed an application with the Japanese Patent Office for an external adapter that would allow legacy console games to be played on a modern platform.
As detailed in the Japanese-language schematics acquired and translated by Siliconera, the adapter includes a processor, a DVD decoder/emulator, a sound processor, and a graphics processor. It also appears as if the device would require its own power source.
Sony Computer Entertainment America had not commented on its Japanese counterpart's filing as of press time.
Backward compatibility on Sony's consoles has enjoyed a storied history. When Sony built the PlayStation 2, it included software emulation for its predecessor's games, allowing a breadth of original PS games to be played on the platform. Initially, a similar tack was taken with the PlayStation 3, whereby Sony included hardware-based backward compatibility for PS2 games and software-based emulation for PS games on the 20GB and 60GB PS3 launch systems.
However, beginning with the 80GB PS3 model, introduced in 2007, Sony transitioned to a software-based backward compatibility method for PS2 games. By the time Sony introduced the 40GB PS3 model later that year, the publisher had opted to forgo backward compatibility for PS2 games outright, though original PS games remained playable on the system.
Sony at the time said of the lack of backward compatibility that it reflected "both the reduced emphasis placed on this feature amongst later purchasers of PS3, as well as the availability of a more extensive lineup of PS3-specific titles."