I really don't know about Sega CD support though. Though probably with the tradeoff of being substantially slower and requiring some frameskipping. A DSTWO specific Genesis emulator (such as a port of PSP's Picodrive for example) would almost certainly sport drastically better compatibility and fewer glitches overall i'm sure. And also explaining the differences as well as some of the pros and cons you'd be dealing with in creating a "better" one for DSTWO. My post was simply an overall explanation on why Genesis emulation on DS is the way it is (for better and for worse).
#Sega cd emulator on gens full
While it would probably be considerably more accurate and glitch-free with better compatibility, it is also likely to be much slower than JenesisDS and require a frameskip to run full speed. Though again it would likely follow the trend of the other DSTWO emulators for SNES and GBA.
#Sega cd emulator on gens psp
I'd wager a Genesis emulator is perfectly possible on the DSTWO, especially since PSP has some. I believe they're ports of the very compatible and much more accurate SNES9x emulator. The DSTWO emulators are considerably slower despite the much faster processor, because they are far more compatible emulators. That emulator is fairly fast and has sound, but the compatibility is even worse than JenesisDS and so are the graphical glitches. It's similar to the situation behind SnemulDS. JenesisDS is a very good emulator considering the DS' limitations and i'd definitely say it's a very nice effort on Lordus' part, but there are reasons it happens to run so well and there exist issues that likely can't be corrected so easily (or perhaps at all) due to the methods by which it was programmed. There was a port of Picodrive to the DS that was a similar situation regarding the speed. It required a frameskip of at least 2 or 3 to get running at full speed. Because it was software-based, it ran quite slow, much slower than later versions of JenesisDS that eventually supported sound.
#Sega cd emulator on gens software
There was actually an earlier version of JenesisDS that came in a software variety (well before sound was implemented), its compatibility was apparently better and it didn't suffer from as many graphical glitches (it also supported scaling the sides of the image and not just the top and bottom). The reason Genesis emulation on DS is so fast is because it's a hardware based emulator as opposed to software. The rest of my post is directed more towards the topic creator and others as i'm sure Rydian knows these things already. It has been done in other emulators that I didn't really notice any significant speed or compatibility reductions. But besides just not ever getting around to it before being recruited by Sega, implementing support for games over 3MB in size likely wouldn't have been impossible to do. A lot of the games actually run quite well already, fullspeed or close to it (there are exceptions here and there as well as slowdowns in some games). The speed I don't know about, though I could possibly imagine it being improved. Either way his name is in the credits but he never appeared online since then. It looks like it actually uses a modified version of JenesisDS with some tweaks and fixes here and there. Turned out he had been hired by Sega themselves to create their official Sonic collection on the DS, Sonic Classics Collection. The author Lordus (AKA Stephen Dittrich) disappeared off the net years ago. I think it's probably fair to say that further improvements likely would have been made to JenesisDS had the author stuck with it.