Analysis

The AtGames Genesis Flashback HD is a Rockchip SoC based device running Android. Genesis/MD and SMS support are provided by two Android apps, one for each respective console. Both apps contain native code for the actual emulation in the form of a shared library (this is standard for NDK apps).

Based on the symbol information included in the shared library for the Genesis emulator, I believe that substantial portions of the emulator are based on existing open source emulators. In particular, the YM2612 and PSG emulation seems to come from Gens with the VDP and IO emulation code from Genesis Plus. 68000 emulation appears to be provided by Cyclone, which is used in Picodrive, but is available separately. Symbols related to Z80 emulation don't seem to match any open source emulators.

Both Gens and Cyclone are available under the GPL license. Genesis Plus was originally licensed under GPL but later switched to a non-commercial license. Source code does not appear to be available anywhere on AtGames' website and the documentation included with the console does not include a written offer to provide the source code. As a result, it would appear that AtGames is not in compliance with the GPL. I've contacted both Stéphane Dallongeville (author of Gens) and Charles MacDonald (author of Genesis Plus) and neither are aware of a commercial licensing agreement that would permit AtGames to use their code without complying with the GPL.

Interestingly, there is some evidence that AtGames is not completely licensing obvlivious. Both Gens and the GPL releases of Genesis Plus contain some code under a GPL-incompatible non-commercial license. AtGames seems to have chosen components from these emulators that avoid the non-GPL portions.

Symbol List

Symbols that match Gens

Symbols that match Genesis Plus

Symbols that match Cyclone

Symbols that match both Gens and Genesis Plus

Symbols that don't match Gens, Genesis Plus or Cyclone