Q: How can I play GBA ROMs on R4 DS or R4i flash cards?
A: The short answer is that you still can not do it. Gameboy Emulator for DSi is compatible ONLY with DS IPlayer cards that have additional 16MB RAM and CPU inside the adapter. R4 SDHC, AceKard 2i, M3i, DSOne, DSTTi, iTouch DS etc. cards are NOT capable of running NDS-GBA emulator do to hardware limitations.
Q: Will future versions of GBA emulator for DSi work on R4, AK2i, R4i, SuperCard etc.?
A: Highly unlikely as it depends on the DS iPlayer hardware to run the emulator, but as this emulator has taught us - never say never
Q: Does GBADSi emulator work on DS Lite and the old NDS?
A: Yes - it sure does, though there are far better solutions for playing GBA Game Backups on the older DS models. Most GBA Flash Cards and special DS Memory Expansion cards do a better job as they do not require software emulation, but rather emulate the cartridge hardware, and let the DS run the game as if it was being played from a an original Gameboy Advance cartridge in the DS slot-2.
Q: What else can I use the DS iPLayer adapter for? I hear it doesn't play NDS roms!
A: Yes - DS iPlayer is about the only DSi Flash Card that does not play the NDS backup roms (it can play all Homebrew DS roms and emulate other consoles). There is a good reason for the makers of iPlayer to block NDS roms from running on it - they wanted it to be fully legal to be sold in any store on-line or offline, when as most R4i cards would be banned from eBay and other stores that want to avoid trouble from Nintendo. iPlayer was made primarily as a media player inside a DS card.
Nintendo NDS & DS Lite has inside 2 x ARM CPU's , one clocked at 33mhz and the other at 67mhz . DSi iPlayer also has two processors, one of which is actually a later and faster version of the processor used in DS. Basically the iPlayer adds its own power to the original DS specs. iPlayer has one ARM9 CPU clocked at 200mhz (more than twice as fast as the normal DS on its own) and a secondary DSP CPU clocked at 400mhz. So DS iPlayer actually has internal specs more powerful than the DS itself, and this is what enables it to run GBA emulation when DS on its own can not.
DSi iPlayer is also capable or running all popular video formats like AVI, RMVB, RM, FLV, ASF, MPG, WMV, MP3, include the DivX & XviD and can even play MKV and H.264. It also works as "DSi Virtual Console for playing emulated GBA, NES, GameBoy Classic, GB Color, SEGA, SNES etc games.
There is one important difference from all the R4i, EZ-Flash and AceKard flash cards that also claim video compatibility -- to play video using iPlayer you do NOT have to CONVERT it, when as for all the other cards you ave to spend time converting the video files on PC in order for them to work on the R4 cards.