Well you could pull off what Acekard did. AceKard R.P.G has a nand chip along side a MicroSD card. Must be a pretty expensive hardware design though...sucks that card is super rare these days. Can't find one for sell anywhere. :P
Interesting. So the timings required by the SDK code are that strict, and SD is that slow? Yeah, I'm not sure how you could have user upgradable storage without using microsd. Unless you could just clip NAND chips in? Depends how standardised...
That might be a good idea, but any of the existing flashcarts actually "proper" flashcarts - i.e. emulating the cartridge protocol like flashcarts for retro consoles? Or do they all "just" patch the games' code in-memory? I know there are very...