help with dc genesis emu options...
 

what does the mode and skip options do?
do they have anything to do with region selection ?
thanks in advance

There are several toggles and switches that you can use on this
emulator to improve/degrade performance. They are as follows:

Graphics MODE0 - Standard, Fastest video mode settings
Graphics MODE1 - Slower, Supports some extra features
Graphics MODE2 - Slowest, Includes Window Layers (Used by some games)
Graphics MODE4 - Same as MODE0 with background skewing

Frame SKIP0 - No Sprite Skipping until maximum reached
Frame SKIP1 - Moderate Sprite Skipping, used to prevent major
slowdown
Frame SKIP2 - Maximum Sprites Skipped

Sound Mode 0 (SOUND0) - Standard Sound Emulation
Sound Mode 1 (SOUND1) - Sound Tempo Increased

You must try all of these settings for every ROM you play to find
the best one.

These settings are toggle-able in our menu system:

To change the Graphics Mode - Press the X button.
To change the Frame Skip Mode - Press the Y button.
To change the Sound Mode - Press the B button.

Just a little addition: I suppose you are talking about SegaGen/Sega Smash Pack loader.
Be aware that it only plays USA roms. You have to force fake USA region code on JAP roms and patch PAL roms with custom patches. I don't remember where to find all this stuff, cause I made my personal CDs almost 2 years ago, but I'm sure there's still some sites with tutorials.