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strygo

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The history of Street Fighter Zero 2 is complicated, with a series of advancements being traded across Japan and the US and the arcade and consoles. The definitive version by features is Street Fighter Zero 2 Dash / Street Fighter Alpha 2 Gold, which was found on the PS2 anthology. I read recently that the anthology was emulated, so that had me wondering: could this version of the game be extracted and run on CPS2 hardware? Has anyone investigated this?
 

DecepticonZero

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Capcom released it in the arcade. ||

1174880393.jpg
 
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strygo

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Not quite - that's an earlier version. A brief run down of the releases:

  • Street Fighter Zero 2 - the original Japanese release
  • Street Fighter Alpha 2 - the international release that added 3 characters (Evil Ryu, EX Dhalsim, EX Zangief)
  • Street Fighter Zero 2 Alpha - the subsequent Japanese release that added these characters and 5 more EX variants
  • Street Fighter Zero 2 Dash / Street Fighter Alpha 2 Gold - the console-only release that adds the prior 8 characters and one more (Cammy)

It's this final release that I'm referring to.
 

DecepticonZero

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Oh, I get you now. That first post had me confused for a second. I was always under the impression that that was a new port which was a mishmash of PSX/Saturn assets on that compilation. The other games were emulated if I remember correctly.

Either way, it seems like that's alot of work for losing dramatic battle and adding Cammy.
 

Rotanibor

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'Vampire Savior Arranged' from the 'Vampire: Darkstalkers Collection' on PS2 probably gets you the most bang for your buck when it comes to this idea. It adds 5 characters to Vampire Savior: Dee, Donovan, Oboro Bishamon, Phobos, Pyron. It is especially desirable when considering how poorly emulated that collection is - there is tons of input lag which was fixed in the later released Street Fighter Alpha Anthology.
 

bagheera369

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You really should notate the most important yet tragic part of the Zero 2 Alpha update....the total annihilation of my favorite Tarot reader...Rose.

She was a goddess in Zero2/Alpha2....they smashed her to bits comparatively speaking, in Z2A.
 

Frank_fjs

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Not quite - that's an earlier version. A brief run down of the releases:

  • Street Fighter Zero 2 - the original Japanese release
  • Street Fighter Alpha 2 - the international release that added 3 characters (Evil Ryu, EX Dhalsim, EX Zangief)
  • Street Fighter Zero 2 Alpha - the subsequent Japanese release that added these characters and 5 more EX variants
  • Street Fighter Zero 2 Dash / Street Fighter Alpha 2 Gold - the console-only release that adds the prior 8 characters and one more (Cammy)

It's this final release that I'm referring to.
Thanks for that rundown, I was always confused as to what the differences were.
 

SelfDeniedHoarderz

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Alpha/Zero 2 is always my favourite. I don't know why but i just dont enjoy Alpha 3 as much
 

Aurich

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Alpha/Zero 2 is always my favourite. I don't know why but i just dont enjoy Alpha 3 as much
They're radically different game really. Alpha 3 is practically an anime fighter in some ways, Alpha 2 is more like a natural extension of ST.

I like Alpha 3 for a lot of reasons, but for playing I think I prefer Alpha 2.

As for the opening topic, I highly doubt there's much you can do with the PlayStation game, it's not something that can just be burned to some ROMs and run on CPS2.
 

strygo

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Well - if Anthology were in fact emulated, it could have been easier for the developers to make the Dash changes to the original CPS-2 code rather than retargeting the source code to the PS2 platform. This seems plausible and an approach I would consider, given the relatively small number of changes that Dash has over the earlier incarnations.

If Dash isn't emulated - it would be theoretically possible to port over the changes to the older CPS2 code. This is a much bigger undertaking, in line with what's being done with Mortal Kombat Plus.

I've taken a look at the files on the Anthology disc and game code seems to be embedded within two large binary files. There unfortunately isn't a folder called "roms\sfz2d" or the like. :D
 
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undamned

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Cool idea! I think on the Vampire games there simply wasn't enough memory space for the entire character roster (hence VSAV 2 and VHUNT 2).
-ud
 
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strygo

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It's been quite some time since I initiated this thread. I had some spare time the last few days to do a bit more digging.

The Street Fighter Zero: Fighters' Generation (Street Fighter Alpha Anthology in the US/Europe) is an interesting release. I didn't appreciate the full extent of its options until digging more deeply just now.

First, the games. The Japanese version has 4 games that are immediately available and 4 more that are unlockable:

  • Street Fighter Zero
  • Street Fighter Zero 2
  • Street Fighter Zero 2 Alpha
  • Street Fighter Zero 3
  • (Secret) Street Fighter Alpha 2 - this is the US/Euro release available in the US/Euro version of the collection
  • (Secret) Street Fighter Zero 2 Dash - this is the US/Euro SF Alpha 2 Gold available in the US/Euro version of the collection
  • (Secret) Street Fighter Zero 3 Upper - this is a CPS2-based back port of the functionality found in the Naomi version
  • (Secret) Hyper Street Fighter Alpha - this is similar to the Hyper SF2 where you can choose from all versions of a character

In addition to these games themselves, there are secret options that allow you to select from the different versions. For example, for SFZ2, you can choose from the 960227, 960306, and 960430 builds. You also have fine-grained control over enabling/disabling the individual bug fixes in each of these releases, so you can play a hybrid version.

Another feature of the collection is the ability to listen to the arranged versions of the soundtracks (the CD audio found on the PSX/Saturn releases). The bulk of the disc is actually this audio in the ADX format.

My primary interest is seeing if I can extract these variants so that they can be played on original CPS2 hardware. I'm still not sure whether the gameplay itself is a port or whether it is emulated. I have some evidence that suggestions it is emulated (below), but it could also be a hybrid of emulation with additional functionality added in.

I've inspected the disc image and found the following:

  • The bulk of the content on the disc is actually the ADX files. I've been able to extract and convert these to WAV files.
  • I found 3 versions of the Q-Sound audio CPU code, matching the CPU code found in the arcade ROMs.
  • I've found what may be the graphics ROMs, but I'm not sure.
  • I've disassembled main executable using Ghidra, but I'm not familiar with the PS2.
I've also attached screenshots of the 3 secret games.

If anyone has experience with disassembling PS2 executables or familiarity with the CPS-2/68000, please let me know. Otherwise, I'll update this thread if I make any more progress.
 

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bagheera369

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Looking forward to the possibility of playing these on the multi, very much....I wish you luck in the hunt.
 

strygo

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I spent a bit more time on this and have made a few more discoveries and have a couple of thoughts.

Vampire: Darkstalkers Collection
This game is built on the same engine and it also comes with arranged versions of 3 of its included games. These arranged versions have extra characters not available in the arcade releases.

Street Fighter Zero 2 Dash / Street Fighter Alpha 2 Gold
It's worth highlighting and reinforcing - this game is not the same as SFZ2 Alpha - it's an iteration on top of that game. The most notably addition is making Cammy fully playable.

MSU-1 Style Audio?
One of the unique features of the PSX/Saturn releases is their CD audio arranged soundtracks. Notable to this collection, these arranged soundtracks are included. It would be cool if these soundtracks could be played on CPS2 hardware. It obviously would require work and likely extra hardware, but it could be a neat addition.

Save State Inspection
Although I was able to find some of the ROM data on the file system (notably, the Q-Sound program ROMs), I wasn't able to find the game data. However, I realized that since there are no load times after selecting a game that everything was being loaded into memory. By inspecting save states, I've been able to find the Q-Sound program and sample data, as well as the program data for games in memory. Unfortunately, the data doesn't appear to be in contiguous chunks in some cases - so the game appears to be copying parts into separate areas of memory. I'm also unsure of how they dealt with the encryption.

Open Questions
  • How are the extra features added to these games? Were they coded into the CPS2 game data or is the collection augmenting the games at runtime?
  • What would be the likely approach for handling the encryption in the games? Encryption removed altogether, encrypted data decrypted at runtime?
  • Is there a good resource for debugging PS2 games? The debugger in PCSX2 is limited (and I don't know its CPU's assembly language :)
 

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Of interest - The Saturn version of Vampire Saviour also has the full character roster like the PS2 one.
 

ChadPhilip

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Just found this thread and hopefully the ROM files for these versions of the game will eventually be unearthed. Getting them to run on CPS2 hardware would be amazing.
 
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