Hi guys, i made some experimentation with the gba running gba carts:
I´ve tryed with 4 mhz crystal and it only speed down, but tried with an array of 8 and 4 and crashes again when switch
When you use only a 4 mhz crystal an change the speed the game not crashes anymore! course it will run slowly, but is safe for now.
In conclusion, i need to borrow some crystals around 5-7 mhz ( i hope fund them in my local store) and try it again.
For future ideas, i will put a triple switch so you can choose between 8 mhz(gb-gbc games) and 5-7 mhz(gba games)