@ samir regarding Sonic CD :
To setup the virtual ram cart for your Sega-CD/Mega-CD game boot the CD or
load your CD image as normal. When the Sega-CD/Mega-CD logo screen appears
press the A, B or C button to access the advanced menu and then select the
memory management features by moving the pointer to "option" or "memory",
depending on the bios version being used. Follow the on screen instructions
to format your virtual ram cart then start your game as normal.
Don't forget that you will need to set up the virtual ram cart function
separately for each Sega-CD/Mega-CD game that you wish to use it with.