It was an example. Snes, NES, etc... All emulated. Most GBA stuff can't be seen in the store, but it is there. I can go to the redownloadable software section and download it (I legitimately own all ambassador games).
Look. I know it won't be done. But that should be the only answer. Saying it CAN'T is just false.
@tivu100 you need complete understanding of both arm9 and arm11. There *are* issues with code allignment between the two, but you can configure the arm11 to handle things like the arm9. That's where HLE comes in. So you also need to know how to write a high level emulator.
And emulating DS games is entirely different than emulating older games. I never said emulation itself wasn't possible. I said reliably emulating the DS wasn't. I'm not even saying you can't Make a DS emulator. I am saying the power is not there to make a good one, you know, one that can actually run games.
It's not a code issue it's a power issue. There just isn't enough. The 3DS would have to run its own processes to keep what is there available as well as emulate a completely different system. Emulation is a very resource intensive process. Even some low end Pcs much more powerful than a 3DS struggle to emulate a DS properly.
And quite frankly it would take more work than someone is willing to invest because it's unnecessary in the current environment.