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 Post subject: Re: Dogyuun, Batsugun, Fixeight, V-V incompatible with OSSC
PostPosted: Tue Jan 14, 2020 12:05 am 


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Joined: 24 Jul 2007
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Location: https://irkenlabs.com/
Unless I fudged up the patching, no dice - getting tile corruption :(


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 Post subject: Re: Dogyuun, Batsugun, Fixeight, V-V incompatible with OSSC
PostPosted: Tue Jan 14, 2020 8:37 am 


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Location: BW, Germany
Ha, it's too good to be true apparently. Especially considering that 3 people had the same idea literally at the same time :D

Toaplan lovers: hey look! we could simply... Fate: what were you thinking Image :mrgreen:

Yeah, I can confirm that with Dogyuun. It looks exactly the same as my previous video capture.
I guess to see a positive side of it, it's the same instead of (completely) different behavior. So the chance grows that it's not a continuum, i.e. if we nail it, we actually nail it without having to worry about arcane spillover effects that aren't immediately apparent.
If that's really the case of course remains to be seen.

TL;DR: The only thing left is to understand how these byte sequences work, or, less preferably, devising a way of efficiently testing many values. Then we've won.

@sergiopolog: do you have a Teki Paki by any chance? You could check if it works with the OSSC, it's the only PCB we don't have empirical info about so far :)


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 Post subject: Re: Dogyuun, Batsugun, Fixeight, V-V incompatible with OSSC
PostPosted: Tue Jan 14, 2020 12:03 pm 


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Joined: 18 Nov 2016
Posts: 15
Location: Barcelona,Spain
@6t8k sorry, that one along with Ghox are the pcbs that I don't have yet for this system :cry:
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 Post subject: Re: Dogyuun, Batsugun, Fixeight, V-V incompatible with OSSC
PostPosted: Tue Jan 14, 2020 12:51 pm 


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Joined: 26 Jan 2005
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Location: Singapore
6t8k wrote:
Working patch for Knuckle Bash added and added a patch for Fixeight!
@parodius: can you try the latter? :)

Just did :
Code:
$ sha1sum.exe tp-026-1.fixeight
56017cc2adeb2fdfd25a992bbf31605b18581865 *tp-026-1.fixeight

Unfortunately, it seems to change nothing at all... There's no graphics glitch like on Dogyuun/Batsugun, and the sync signal is still messed up in the same way as before.


6t8k wrote:
Fixeight is an interesting special case, because it uses two different checksums (at 0xc0 and 0xc4), and it traverses the loop twice, one time checking against one checksum for even bytes and one time checking against the other checksum for odd bytes (ROM EVEN ERROR vs. ROM ODD ERROR). So basically everything is the same, it's just that you have to go through the process described above twice and change both checksums accordingly.

By the way, as per parodius' reportings, changing occurences #1 and #3 in Fixeight leads to a blank screen. I could confirm that these lock up the game even before the integrity check is called, so as suspected, #2 is the occurence to change.

Thanks for the explanations. Any idea what to try next for FixEight ? 8)
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 Post subject: Re: Dogyuun, Batsugun, Fixeight, V-V incompatible with OSSC
PostPosted: Tue Jan 14, 2020 8:23 pm 


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@parodius: my bad, somehow the impression snuck in that the #3 occurence can't be changed without provoking the black screen - however, in contrast to #1, it can! Could you re-download and re-apply? :)

---

6t8k wrote:
It's certainly possible that it would've been enough to change only one specific byte within that "configuration string" to achieve this.

Yes. I've tried a few variants for Dogyuun, not yet reaching both OSSC compatibility and sound graphics at the same time however. Here are the results:

Spoiler: show
Code:
(byte order on disk)

0202, 0302, 0040 <- first controller
0212, 0312, 0050 <- second controller
[A] (original values, but set the next-to rightmost bit to 0 akin to "OSSC compatible" values)
Results: OSSC recognizes the signal, but game has graphical glitches, the same as can be seen on the previous video capture

0302, 0202, 0042 <- first controller
0312, 0212, 0052 <- second controller
[B] (original values, but swapped the first two words each because in "OSSC compatible" values, the 3 comes first)
Results: OSSC does not recognize the signal, but game is fine (like unpatched ROM)

0302, 0202, 0040 <- first controller
0312, 0212, 0050 <- second controller
[C]  (A and B combined)
Results: did not try due to above results

0202, 0302, 0041 <- first controller
0212, 0312, 0051 <- second controller
[D] (original values, but set rightmost bit to 1 as a "compromise" between original values and A)
Results: OSSC recognizes the signal, but graphical glitches are much, much worse. almost everything is missing aside from backgrounds.


So the rightmost byte (order on disk) seems to be responsible...


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 Post subject: Re: Dogyuun, Batsugun, Fixeight, V-V incompatible with OSSC
PostPosted: Tue Jan 14, 2020 11:03 pm 


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Joined: 26 Jan 2005
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6t8k wrote:
@parodius: my bad, somehow the impression snuck in that the #3 occurence can't be changed without provoking the black screen - however, in contrast to #1, it can! Could you re-download and re-apply? :)

Code:
sha1sum.exe tp-026-1.fixeight
3763350f56af46477bc30e60274cb277f47cb4a9 *tp-026-1.fixeight

No dice, still the same.
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 Post subject: Re: Dogyuun, Batsugun, Fixeight, V-V incompatible with OSSC
PostPosted: Wed Jan 15, 2020 11:54 am 


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parodius: Hmm.. if it's the #1 occurence we may be out of luck for the time being. :?
Someone would have to step through the instructions to find out why changing the bytes there prevents the game from booting and see if something can be done to remedy that.

The only other possibility I can think of right now would be that Fixeight could (for some strange reason) use the values that are normally fed to the second GP9001, which are always stored adjacently even for games that have only one GP9001 like Fixeight does.
I'll create a corresponding patch shortly that you can try if it's not too much trouble at this point so we can rule that possibility out.


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 Post subject: Re: Dogyuun, Batsugun, Fixeight, V-V incompatible with OSSC
PostPosted: Wed Jan 15, 2020 12:17 pm 


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No trouble at all.
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 Post subject: Re: Dogyuun, Batsugun, Fixeight, V-V incompatible with OSSC
PostPosted: Wed Jan 15, 2020 8:53 pm 


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Revised the Fixeight patch, please retry.

I'm now quite sure though that the first occurence is the relevant one..

A few observations in regards to the black screen boot failure: it seems like there is another integrity check or something.
The failure is in fact triggered when any address between 0x100..0x70EE is modified. All bytes within that range are processed and afterwards, an infinite loop waits until 0xFF appears at 0x28F001, which is memory shared with the V25 audio CPU I suppose (?). This eventually happens (not from within that loop), but when any byte within the aforementioned range is changed, 0xFD appears instead.
If I manually set that value to 0xFF via the memory viewer, the game boots with upside down graphics, in Taiwanese region, has no audio and crashes when a credit is started. Interesting.


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 Post subject: Re: Dogyuun, Batsugun, Fixeight, V-V incompatible with OSSC
PostPosted: Wed Jan 15, 2020 10:50 pm 


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Joined: 26 Jan 2005
Posts: 546
Location: Singapore
Code:
sha1sum.exe tp-026-1.fixeight
be33802651f983ce081d203715a7e3c8ddcc9d4b *tp-026-1.fixeight

Unfortunately, I couldn't see any difference with this patch either.
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 Post subject: Re: Dogyuun, Batsugun, Fixeight, V-V incompatible with OSSC
PostPosted: Thu Jan 16, 2020 8:20 pm 


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Joined: 14 Aug 2019
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Location: BW, Germany
Yeah, they seem to have done things differently with Fixeight for some reason..
Removed the patch until there's a way to work around the above-mentioned issue. I'm sure it's possible somehow.


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