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 Post subject: Own a weird Thunder Force AC board - any TF experts here?
PostPosted: Mon Mar 16, 2020 1:38 am 


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Joined: 30 Aug 2012
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Hey all, sorry if this isn't the appropriate place to ask but I'm not sure where to turn to!

Picked up a Thunder Force AC board locally for $50 CAD. The ROMs didn't look genuine but it DID look like a legit Sega System C2 board. The guy showed me the game played and it was only $50 so hey, I picked it up. I've never really played the series before so I just credit fed to Stage 5, and after destroying the boss the game faded to black and looped back to the title screen. Confused, I looked up the game on Youtube and found my copy is different than the retail, the most obvious to me being:

    1) The intro on mine is missing the background and the music is completely different. No cool tech!
    2) The game has no voices at all. Lame!
    3) Weird little differences - font colors are slightly different on the "How to Play" screen and text is changed
    4) Stage 4 is "Haides" and Stage 5 is "Ellis", which apparently don't exist at ALL in AC(?), just in Thunder Force 3 on the Genesis
    5) Again, game ends after Stage 5

I imagine there might be other differences like patterns and whatnot, but I know nothing about Thunder Force so I hope there's some experts on here to inform me.

Here's some pics of the board and the ROMs - notably, my understanding is that it should have 5 EEPROMs instead of 4? I originally assumed that the missing voices and background could be due to the missing ROM, but the game works fine otherwise, and it wouldn't explain the different stages...
https://imgur.com/1dvFnQH
https://imgur.com/vP6aMF4

Package also included a scan of an original manual page presumably:
https://imgur.com/HhlQca5.jpg

I've gone ahead and recorded the attract screen on real hardware, which conveniently goes through all the stages in the game, albeit not to the bosses. Take a look here:
https://youtu.be/wm6afQfh1lw

I'm mostly just asking the wider community if this is some known dump, bootleg, hack or version of the game, and if it already exists on the web, I can safely replace the chips and actually play the full game haha.
If this is, somehow, an undumped version of the game, then let me know how I should properly document and dump the ROM! I own a GQ-4x4 and I imagine I could dump them, but I want to make sure I'm not forgetting some valuable board documentation :P


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 Post subject: Re: Own a weird Thunder Force AC board - any TF experts here
PostPosted: Mon Mar 16, 2020 6:58 pm 



Joined: 08 Mar 2019
Posts: 82
Looks like it might be some kind of prototype, hand-written labels with checksums on is usually a fair indication. The sample ROM isn't present (empty socket) hence no speech, but maybe it wasn't implemented at this point in time (or has been removed / lost)

Would definitely be nice to see a dump of it. There have been a few interesting prototypes people have contributed to the community recently (eg. GunNail, and the Raiden 2 build that was posted here) so I guess this has the potential to be another.

The only thing to keep in mind if you want to ROMswap the proper game on there is the protection chip. The final game uses a 317-0172, yours is just marked T-Force so no guarantee it's the same.

If you dump it, drop me a private message and I can take a look at the dump (and potentially tell you if the protection looks the same) (I wrote the Thunder Force AC emulation in MAME fwiw)


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 Post subject: Re: Own a weird Thunder Force AC board - any TF experts here
PostPosted: Mon Mar 16, 2020 9:05 pm 



Joined: 12 Feb 2005
Posts: 241
Location: North West - UK
That is some (2) post OP what was your first :)


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 Post subject: Re: Own a weird Thunder Force AC board - any TF experts here
PostPosted: Tue Mar 17, 2020 3:48 am 


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Joined: 06 Oct 2012
Posts: 294
Location: Seattle, WA
MameHaze wrote:
... (I wrote the Thunder Force AC emulation in MAME fwiw)


Expert found


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 Post subject: Re: Own a weird Thunder Force AC board - any TF experts here
PostPosted: Tue Mar 17, 2020 4:00 am 



Joined: 20 Apr 2018
Posts: 125
Yes, thanks for posting and dumping!

Also, after the dust has settled, grab your self the Sega C2 multi. The system has some great games on it, so why limit yourself to just one game!

https://www.arcade-projects.com/forums/ ... /&pageNo=1


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 Post subject: Re: Own a weird Thunder Force AC board - any TF experts here
PostPosted: Tue Mar 17, 2020 2:17 pm 



Joined: 20 Apr 2018
Posts: 125
This potentially could be a MD version of the game, see the link for the C2 multi to see discussion. Please don't let that dissuade you from dumping it however, it could still be an unknown version.


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 Post subject: Re: Own a weird Thunder Force AC board - any TF experts here
PostPosted: Tue Mar 17, 2020 2:29 pm 



Joined: 08 Mar 2019
Posts: 82
That seems unlikely.

What is more likely is that Thunder Force AC started off as the MD TF3 game, and was changed over time by the developer until they ended up with the final Thunder Force AC product. This is a probably a build that's still closer to the MD code than the final arcade, an intermediate build.

I doubt anybody outside of Technosoft would go to the lengths to make a conversion and give it the 'AC' title screen when they could easily just bootleg the proper game.

Anyway, it'll be interesting to study the code once it's dumped if the owner decides to do that (studying the code is often the most interesting part of these things)


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 Post subject: Re: Own a weird Thunder Force AC board - any TF experts here
PostPosted: Tue Mar 17, 2020 7:01 pm 


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Joined: 18 Jan 2017
Posts: 25
MameHaze wrote:
That seems unlikely.

What is more likely is that Thunder Force AC started off as the MD TF3 game, and was changed over time by the developer until they ended up with the final Thunder Force AC product. This is a probably a build that's still closer to the MD code than the final arcade, an intermediate build.


More evidence that Thunder Force AC started off as the Mega Drive game is that the map & highlight at the start of each level is still in the final arcade game code - just bypassed.

https://tcrf.net/Thunder_Force_AC


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 Post subject: Re: Own a weird Thunder Force AC board - any TF experts here
PostPosted: Tue Mar 17, 2020 7:41 pm 


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Joined: 30 Aug 2012
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MameHaze wrote:
Anyway, it'll be interesting to study the code once it's dumped if the owner decides to do that (studying the code is often the most interesting part of these things)


What am I gonna do, sell it to some guy who'll just put it on a shelf and never play it for a couple hundred bucks?
That being said, if anyone wants to send me a C2 multikit, I'll humbly accept it 8)

Dumped the four ICs, is that all you need? Check your PMs my man.

Also, looks like they left a build date on the ROM:
Image

EDIT: How did I not notice the final game had no stage intros?? Talk about not seeing the forest for the trees lol
Thunder Force AC is pretty dope though, hope to be well acquainted with the final version soon!


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 Post subject: Re: Own a weird Thunder Force AC board - any TF experts here
PostPosted: Tue Mar 17, 2020 8:33 pm 



Joined: 20 Apr 2018
Posts: 125
Thanks for dumping this man! You still have a very cool piece of history there. Also, you got it for a STEAL. TFAC for $50? GTFOOH with that! :P

Get the multi though, seriously, TFAC isn't even my favorite game on there! Ribbit is now, what an evil game...


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 Post subject: Re: Own a weird Thunder Force AC board - any TF experts here
PostPosted: Tue Mar 17, 2020 9:39 pm 



Joined: 08 Mar 2019
Posts: 82
Got the PM, having a look now.

Some people don't want to share things once they find out they might be rare / valuable, so I don't like to make assumptions. I'm glad you're on the side of helping to document history in a way that people can verify and see for themselves instead.

The header / build date is from the retail version of TF3 for the MD, but probably just left there while they worked on this.


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 Post subject: Re: Own a weird Thunder Force AC board - any TF experts here
PostPosted: Tue Mar 17, 2020 11:36 pm 



Joined: 08 Mar 2019
Posts: 82
Current state, it kinda runs, but one of the ROMs is a bad dump, there's data corruption in a weird pattern and the checksum doesn't match, I've asked if it can be redumped (clearly the chip worked at the point the video was made, as it causes first stage graphics and collision tables to be entirely broken)


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 Post subject: Re: Own a weird Thunder Force AC board - any TF experts here
PostPosted: Wed Mar 18, 2020 12:17 am 


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Joined: 30 Aug 2012
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MameHaze wrote:
Current state, it kinda runs, but one of the ROMs is a bad dump, there's data corruption in a weird pattern and the checksum doesn't match, I've asked if it can be redumped (clearly the chip worked at the point the video was made, as it causes first stage graphics and collision tables to be entirely broken)


Redumped, checksum matches now. Check yer PMs, hopefully this one works heh.


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 Post subject: Re: Own a weird Thunder Force AC board - any TF experts here
PostPosted: Wed Mar 18, 2020 12:26 am 



Joined: 08 Mar 2019
Posts: 82
Yep, looks better

I was a little concerned at first, because sometimes when you get the kind of pattern I was seeing it indicates some kind of internal cell failure in the chip, as it wasn't a dodgy connection on one of the lines. Thankfully the new read appears correct.

I need to do some investigation as it currently sets input ports to output mode then attempts to read from them (which clearly works on the original hardware, so our understanding must be incorrect somewhere) It doesn't seem to touch the protection outside of initializing it, so it's difficult to say if the chip on the board will be correct for the final game (although if you multi-game it that shouldn't matter)

The game does not appear to trigger speech samples, so I think that part was simply not yet programmed in (there don't appear to be entries in the sound test for speech either)


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 Post subject: Re: Own a weird Thunder Force AC board - any TF experts here
PostPosted: Wed Mar 18, 2020 12:34 am 


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Joined: 30 Aug 2012
Posts: 5
MameHaze wrote:
Yep, looks better

I was a little concerned at first, because sometimes when you get the kind of pattern I was seeing it indicates some kind of internal cell failure in the chip, as it wasn't a dodgy connection on one of the lines. Thankfully the new read appears correct.

I need to do some investigation as it currently sets input ports to output mode then attempts to read from them (which clearly works on the original hardware, so our understanding must be incorrect somewhere) It doesn't seem to touch the protection outside of initializing it, so it's difficult to say if the chip on the board will be correct for the final game (although if you multi-game it that shouldn't matter)

The game does not appear to trigger speech samples, so I think that part was simply not yet programmed in (there don't appear to be entries in the sound test for speech either)


Neat! Let me know if there's anything in particular you'd like to know about the board, or anything else I can do to help
Glad it's out there in some capacity at least!


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 Post subject: Re: Own a weird Thunder Force AC board - any TF experts here
PostPosted: Wed Mar 18, 2020 1:30 am 



Joined: 08 Mar 2019
Posts: 82
C2 boards are fairly well documented etc. anyway, so there's not much more can be detailed that isn't known.

The protection chip isn't something you can just dump, and while the PALs/GALs might be, not every programmer can read them, and there's a chance they'll be protected anyway.

I uploaded a video of it running in MAME
https://youtu.be/xZ4xuRku4VI

I apologize for the poor gameplay at the end, it's been many years since I played this one and it's early AM here.

Thank you for taking your time with this, such versions are always interesting to see.


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 Post subject: Re: Own a weird Thunder Force AC board - any TF experts here
PostPosted: Sun Mar 22, 2020 3:13 pm 


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Joined: 11 Jun 2008
Posts: 256
Location: London
Thanks for posting and dumping this Gmegbln. :D

Will this turn up in MAME eventually? I'd really like to try and get it running on one of my boards.
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 Post subject: Re: Own a weird Thunder Force AC board - any TF experts here
PostPosted: Sun Mar 22, 2020 4:47 pm 



Joined: 08 Mar 2019
Posts: 82
It'll be supported in 0.220, whatever it is.


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 Post subject: Re: Own a weird Thunder Force AC board - any TF experts here
PostPosted: Sun Mar 22, 2020 5:13 pm 


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Excellent, thanks.
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 Post subject: Re: Own a weird Thunder Force AC board - any TF experts here
PostPosted: Fri Mar 27, 2020 9:46 pm 


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Massive thumbs up for discovering and dumping this :)
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 Post subject: Re: Own a weird Thunder Force AC board - any TF experts here
PostPosted: Thu Apr 02, 2020 9:45 am 


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Posts: 125
I own a PCB with the exact same issues.
Always thought it was a failed conversion and was looking for someone to reprogram the eproms.

Original as it it, it is still frustrating not being able to play a full game on it. Rebooting at the end of stage 5 make you feel you play a demo version...


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 Post subject: Re: Own a weird Thunder Force AC board - any TF experts here
PostPosted: Thu Apr 02, 2020 2:49 pm 



Joined: 08 Mar 2019
Posts: 82
Yeah, quite a few people have now come forward to say they own this (and didn't realise it wasn't supported in MAME)

I imagine somebody made a fair bit of money from selling these somewhere...

I guess it must have been before PCB prices shot up to 'you must be stupid if you buy them' levels because I don't see converting to this adding much value unless you're trying to pretend every single copy is one of a kind, although there's a good chance that would have been the case, because if you were converting to Thunder Force because Thunder Force was worth more than say Columns then you'd just hack regular old Thunder Force AC (minus samples) for your conversion, no real reason to put this on your PCBs.


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 Post subject: Re: Own a weird Thunder Force AC board - any TF experts here
PostPosted: Thu Apr 02, 2020 4:12 pm 


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So... it's still unclear whether this is the work of a very dedicated hacked/bootlegger or a genuine proto?

It kind of reminds me of the Street Fighter II Turbo on Mega Drive.


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 Post subject: Re: Own a weird Thunder Force AC board - any TF experts here
PostPosted: Thu Apr 02, 2020 6:29 pm 



Joined: 08 Mar 2019
Posts: 82
My theory remains that somebody got hold of a proto then mass produced conversions of other boards to it. There are still mistakes that make no sense at all if it were homebrew and the person creating it had access to the final AC build. (eg. errors in the I/O code, when instead you'd just borrow from the final if you were going that route)


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 Post subject: Re: Own a weird Thunder Force AC board - any TF experts here
PostPosted: Fri Apr 03, 2020 12:20 pm 


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Yes, that makes sense. Well, I guess it's good in a way that there's a new proto which has been dumped.

I'd be curious to know if other people's dump of this proto match this one.


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