Genesis Plus is an emulator of the Sega Genesis / Sega Megadrive. This is a port of Charles MacDonald’s Genesis Plus to the GameCube, with a lot of improvements.

Changes:

Core/VDP
improved VBLANK flag accuracy, as observed on real hardware.
improved DMA operations accuracy, writes are now performed on a scanline basis: fixes Gaiares (flickering title screen).
improved DMA Fill timing accuracy.
fixed DMA with bad code values: fixes Williams Arcade Classics (corrupted gfx after soft reset).
fixed horizontal resolution changes during HBLANK: fixes Bugs Bunny in Double Trouble (2nd stage).
fixed Vertical Counter in interlace mode 1, as observed on real hardware.
fixed horizontal border width, as observed on real hardware.
various code improvments & optimizations.

Core/Extra
improved savestate format: added DMA, SVP, cartridge mapping & internal registers state informations
improved unlicensed ROM mappers emulation
added Chinese Fighters III mapper support
added Top Fighter mapper support
fixed Barver Battle Saga mapper support
fixed cartridge hardware soft-reset (Game Genie, SVP, …)
fixed Game Genie registers byte reads

Gamecube/Wii
added message box when inputs config uses disconnected controllers.
added message box when settings are reseted to default on startup.
fixed default inputs configuration.
fixed memory leak in Cheat Menu causing spurious resets.
added an option to enable/disable automatic cheat activation
increased max number of cheat codes
optimized cheat codes requiring RAM patching.
improved default horizontal scaling to better match output from a real Mega Drive

Gamecube specific
fixed inverted keys in cheat menu.
fixed audio input frequency, now use exact audio hardware samplerate, as measured on my Game Cube (~48044 Hz),

(NB: Wii samplerate has been verified to be closer to 48000 Hz)

Wii specific
added the possibility for any wiimotes to be used as input device, regardless of the connected expansion controller.
fixed USB drive not being detected when application is loaded from USB (HBC), thanks to Tantric for the tips.

http://wiibrew.org/wiki/Genesis_Plus