So as some people have correctly guessed, Genesis/Megadrive is the next system in RetroCopy, release date to be announced soon. Seriously who falls for the old SNES Sonic hack trick? 
Now what follows is simply some of my opinions about the state of Genesis/MD emulation, so any easily offended emulator programmers out there take the Xanax...... now. So why Megadrive? I was going to add SNES first but I decided it wouldn't be fair to byuu who seems to be really trying to improve BSNES, I want to see where he goes with it. Well that's only part of the reason, the other is the Motorola 68000 is used in a lot more machines and I wanted to add a 68K core.
The unfortunate news is it isn't my 68K core, I just can't be bothered at this stage to write one when so much else needs to be done. Instead it is the same one used in MAME, the Musashi core. It's not perfect, but it's likely the most accurate 68K emulator out there at this moment. At some point in the future when things settle down I will write one myself that is cycle accurate. Compared to other emulator cores the 68K is quite a beast, probably double the amount of code compared to a Z80 emulator which in itself is larger than the majority of cores out there because of the amount of instructions. That said I haven't picked it to bits yet like the Z80/6502 to know how large a cycle accurate version may be, it may be tighter than most out there.
So this marks the time a non cycle accurate core is in RetroCopy, is it doom and gloom? Not really, RetroCopy will be the first Genesis emulator that I'm aware of to feature cycle accuracy in the VDP, Z80, YM2612 and PSG cores. ie besides the 68000 it's cycle accurate. I have also tweaked how the interactions between the CPU and other components are done, giving a much tighter synchronization between components, audio/Z80 won't be as "lagged" in regards to write synchs as it is in other emulators.
I'm not going to be going overboard with the Genesis yet and adding support for all the extra input devices, EEPROM chips, so emulators like Kega/Gens will still have a place. These things will come later, instead you'll get a stock standard, 3button/6button, pal/american/japan type options and the best accuracy available. It's also pretty fast, if you can run the benchmark in v0.500B and get greater than 1.5 you should be fine.
I was quite surprised about the accuracy of other Genesis emulators, for some reason I thought they were at a pretty good stage. Kega does have high compatibility, but it fails (as does GENS and REGEN) on a lot of tests, like this one :-
This is a test made by Nemesis, an aussie that has done quite a bit for the Megadrive emulation scene. I believe he has a very accurate emulator using some new threading techniques that isn't released yet, I look forward to seeing what it is capable of! I was quite surprised by how much the cycle accurate VDP I did for SMS helped with making the Genesis VDP. There is a lot of knowledge I have now that I couldn't find anywhere else, so maybe I'll have to write a document for others at some point about the MDVDP internals.
Now onto something a bit more subjective. Back in the day Gens used to be my favourite Genesis/MD emulator, it was fast and looked and sounded good. Somewhere along the way Steve Snakes new emulator Kega took over (he had worked on earlier GEN emulators) and Gens fell into the background. Now Kega is a good emulator in my books it improved on Gens in a number of areas , has high compatibility, lots of options and Steve Snake's love of the console permeates throughout.
Now I'm not about to discourage people from releasing emulators but Regen to my eye looks like a real big Kega rip off. I'm not sure if it does anything better emulation wise over Kega, but the emulator looks like it's trying to clone Kega. Now Regen is a fairly decent emulator, it also has high compatibility and lots of options, but what is the point of it? I just don't understand why some people don't put a bit more love into their emulators that they spend years working on. If you're goal is to emulate another emulator then maybe it's mission achieved. MEKA, Gens, Kega, ZSNES they all have a lot of heart in them and I like that.
Anyhow now that's off my chest let's look forward to some 16bit action in RetroCopy, it will probably be available within a week. This version is going to be numbered between 0.500 and 0.600 because of roadmap issues (0.600 is supposed to feature various things that aren't ready yet). So if anyone has a good version number to use (atm I'm going with v0.555) speak up and you may see it around the internet soon!
And if you haven't yet voted, go here http://www.retrocopy.com/forumthread/74-1/poll-the-next-system-to-be-added.aspx to vote for the next 8bit system you want in RetroCopy.