Does anybody know if there exists a flashcard for the GBA that has i/o ports (of *any* kind, 8mm, USB, etc) that can be accessed by software on the card during runtime? That is, I want to send data/messages out of the gameboy thru the flashcard while it's running...and not to another gameboy. Does anyone know of such a card? Also, if anyone knows where I might find a specific write up of what signals get sent thru the link cable, (again not just relevant to the gba that'd be receiving it) I'd be interested to know about it. Thanks everyone for your time. =)

*bump*

Yeah, I guess this was pretty obscure but I figured it couldn't hurt. Thanks anybody who took a peek. =)

I'm sure you can use the GBA link port to communicate with something other than another GBA.

Check this out, or google for "GBA link cable parallel" or similar.

I'm not quite sure why you would want to communicate with the flash cart, other than to store information on it. However, you can reprogram the flash cart from the GBA, check out gbatek reference for information on how to reprogram various flash carts. Not all of them support it, and among those that do, the interface is not the same. So not amazingly useful for demos.

Ha. I totally forgot the gameboys had link ports on them; looks like that's the interface I'll be using. Thanks everyone. =)