Yeah, annoyed the crap out of me, too. I assume, given that it's more or less literally one byte incorrect, that there'd be a simple Game Genie/PAR code to fix it...?
AFAIK, Mairtrus doesn't even have a wiki page. Claiming it, I will write a first revision soon (just so we don't do a duplicate work). edit: done.
Not exactly. The 6502 ASM is mostly converted straight into 68k ASM, with a few manual fixes. The PPU is emulated - the code "thinks" it's writing to a PPU, but it's really writing to RAM and the values translated to equivalent VDP commands. Haven't done a whole lot of observation in a good debugger. The APU is simulated - he wrote a music engine, converted the song data from the original NES data, and uses it in lieu of actual APU emulation. It's a sort of hybrid, in a way.
If I recall correctly, he didn't emulate the APU because he didn't get something to work. Maybe he'll do it later?
I've been talking with Mairtrus, and am working on a more accurate palette. I have two, actually - one based on the YUV palette generated by home consoles, and one based on the RGB palette used on the Playchoice-10 (and on all those wonderful screenshots in Nintendo Power). YUV palette: RGB palette: YUV palette with Blargg's NTSC filter: RGB palette with Blargg's NTSC filter:
That's excellent! Oh, I have a question. Theoretically, would it be possible to port over the All-Stars graphics (or enhance the game to benefit from the Genesis' extra power in any other way)?
What I've heard in this topic reminds me of Sonic & Knuckles Collection, which also has converted instructions, emulated display, and a different sound system. Just a thought I had.
Yeah, and I'm pretty sure that the author is at least considering doing so in future versions. It seems like this was just more of a "proof of concept" type thing, but a hell of a proof of concept it is.
In re sound emulation: It is sorta possible to emulate the APU if you're willing to dedicate the time to generating the sample data in software, mixing, and writing to the FM chip's DAC. The PSG in the Genesis can't do much of what the 2A03 does (only the 50% duty, and in a more limited range), and the white noise engines are 100% different so you'll most likely never get perfect 2A03 noise emulation from the PSG. The question is: will emulating a 2A03 on the Z80 be slow? Also in re CONVERT GAME XYZ FOR ME PLZ: sheesh guys, it's his converter and he can do whatever the fuck he wants. Leave the guy alone and write your own converter.
First of all, we don't need perfect emulation, only something that resembles it, so let's see: Triangle waves: I guess a good FM instrument could do it Square waves: PSG can do it Noise: PSG can do it; even if it works differently, it's still noise 1-bit PWM: Super Mario Bros doesn't even use it! The big problem here would be converting the triangle wave frequency into something useable by the YM2612.
Slightly deformed sine can sound rather close to triangle channel sound... easy to achieve too on FM 50% Square waves are piece of cake, either in FM or PSG... FM will give you better range though and you can get linear volume levels like NES does instead of log 9FM is log too, but there's enough resolution to get linear scale worked out). 25% Square waves are tricky, you will not be able to get exact waveform, but you can approximate it... the sound will be slightly softer though 12.5% Square waves are also tricky and a bit more bitch to approximate, and again sound will be a bit softer... Z80 does have enough oomph to emulate the 2A03 at decent sample rate, but I'm not gonna write that code :P
Because it's clearly impossible to do semi-accurate renditions of NES music on an MD... </sarcasm> EDIT: BTW, that doesn't even use the PSG tones, I did the squares on FM just because.
Actually, this was the precise VGM I was thinking of when I was talking about how the music had been done better elsewhere on the system by our community =P
That's not the VGM I posted back in october 2008, I changed this one to use FM instead of PSG tones just to prove a point =P
Yeah, but would it still be possible to do the duty cycling and other stuff on the FM chip? Probably not so easily... And besides, the 2A03 emulator would just an exercise in Z80 programming =P
This is almost perfect! There's a small flaw in that mario's bounce height on the goombas isn't perfect. Funny how he didn't use the PSG for the overworld melody - that's the exact same kind of square wave used in the NES game You can come really close to all of the 4 duty cycles and triangle wave of the NES on the YM2612 alone. Oh. I'm pretty sure the audio isn't converted from the original format - there are a few tonal errors, most noticeable in the end of level theme.
I haven't noticed this, could you elaborate further? All I know is what Mairtrus said, which was that he converted the sound data from the original NES data. I have noticed the tonal errors you mention, but I chalked them up to differences between the capabilities of the 2A03 and the 2612 - in the same vein, while making the more accurate palettes, I noticed that due to the 9-bit RGB that the MD generates, some colors are slightly off from the colors the NES generates, because the NES has no such 9-bit restriction (especially in the YUV palette, some of the pastels are impossible for the MD to generate without mucking about with highlight mode).
I downloaded this a few days ago, and may I say that I'm very impressed! To be honest, my first thought was: "Is the Genesis ALLOWED to play this game?" :P I played through a few levels though, and it seems to be very accurate. The Genesis rendition of the music sounds funny, but I'm so used to the classic 8-bit soundtrack. To Mairtrus, LocalH, and whoever else working on this project: Excellent job.
