Wii7800 is a port of the ProSystem emulator developed by Greg Stanton. Additional changes developed by Ludovic Jacomme aka Zx-81 (PSP port), Leonis, and gdement.

Changes:

* GX based scaler (smoother scrolling in Plutos, Xevious, Motor Psycho)
* Ability to adjust screen size to any size/dimensions via the “Screen Size” option under “Display”. If this is entered after loading a cartridge, the last frame will be displayed to assist in sizing.
* Fixed graphical glitches in Ballblazer
* Implemented RANDOM (read) and SKCTLS (write) for Pokey sound emulation
– Ballblazer now plays all sounds
* Minor refactor of Pokey code
* Some minor adjustments to the Light Gun related code
* Updated palette (from Underball)
* Updated menu code, GX rendering of dip switches and debug information
* Ability to set HBLANK period, Dual-analog support in ProSystem database

http://www.wiibrew.org/wiki/Wii7800