Nonsense Man wrote:
Finally how would i build in a charging port? And i know how to oc it( I'm pretty sure you just have to replace the crystal).
I can help you here. For my GBC, I used the guts of a GBC rechargeable battery pack as a charging circuit. I removed the battery contacts from the GBC board and wired them to the charging circuit the same as the battery pack had been. Then I removed the EXT port for the plug for the charger. So from the outside it appears stock (if it wasn't clear purple, at least). Now I can throw a pair of NiMH AA's in it and I can charge them of play.
I also OC'd my GBC, and the way to OC a GBA is very similar, you just need a different value crystal. I changed my GBC from an 8MHz crystal to a 14MHz one and its still playable. The GBA uses a 4MHz crystal, so a 7MHz crystal is required to have a similar speed increase. Only problem is finding a 7MHz crystal, as 14MHz are in many devices so it was easy to find one, but not so with the 7MHz (or else my GBA would be OC'd).