How I Solved the DC VA0 JAP Black Screen Issue in Four Games!

[CrisMod]

Hello, folks! As I was going through my Dreamcast library to compile a comprehensive list of working settings/presets for running games with the Dreamshell IDE modification in 2023, I aimed to provide an easier way for the community to access and enjoy these games, especially with the specific hardware combination I'm using (which I'll share once the list is complete).

I've encountered a peculiar glitch issue in certain games that only affects the Japanese Dreamcast VA0 model, and I haven't been able to find a solution for it, even after seeking advice from various sources. Let me clarify that I'm well-positioned to make this assertion because I own three different Dreamcast models from various regions, and I'm a self-taught modder who ensures my Dreamcast consoles are in top working condition from a hardware standpoint.

While conducting experiments on my Japanese VA0 Dreamcast, the first game affected by this problem was "Looney Tunes Space Race." This game refused to boot on the VA0 Japanese Dreamcast, as it worked fine on the VA1 Japanese version. The farthest I could get with various Dreamshell settings was the Sega logo, followed by a black screen.

I tried everything with DreamShell, different types of dumps, and every possible combination of settings, but the game wouldn't start, and I was certain that it wasn't due to the modification. Following this, I conducted experiments with the three different Dreamcast models, using the real GD-ROM and physical discs. To ensure a precise, scientific verification, I performed a third test with the serial port and the same adapter and SD card in all three consoles under identical conditions (same gamepad, same VMU, renewed PSUs, all three with renewed GD-ROM hardware, and I even tried it without the VMU), and the "VA0 Japanese" model consistently experienced the black screen issue when running Looney Tunes. Other games worked fine up to that point, leading me to believe that there's something unique in the VA0 Japanese hardware that hasn't been noticed before when compared to other Dreamcast versions (even in front of the VA1 Japanese version, which booted the game without issues).

Setting aside Looney Tunes, as I continued with numerous tests, I encountered three more games with the same problem, bringing the total to four games (out of an extensive library of nearly 650 games). This issue seemed unrelated to the game's region or version. The affected games are:

1. Looney Tunes Space Race.
2. Soldier of Fortune.
3. Speed Devils - Online Racing (only the online version; the normal version doesn't have this glitch on the VA0 Japanese model).
4. UnderCover AD2025 Kei (Japan).


Thanks to the last game, UnderCover AD2025 Kei, I discovered the glitch that resolved the boot issue for the other games. In UnderCover AD2025 Kei, the game consistently froze at the same point after nearly 15 minutes of gameplay. Initially, I thought it might be a loader or incorrect settings causing the block, but the strange part was that the game always froze at the same point with other settings as well. So, I considered it might be an issue with the image and tried different ones, but the problem persisted. As a last-ditch effort, I tried playing without the VMU, and the game still froze.

Frustrated after countless hours of tests and unsuccessful attempts with Dreamshell, I began to suspect that the issue might be related to the VMU's memory access. My VMU had been filled with save data after testing over 600 games, and I thought that maybe using a different empty 4MB VMU or what so ever in place of the original one could provide some form of memory control at that specific point (I had tried playing without the VMU earlier, and the problem still occurred). To my surprise, using the empty VMU allowed the game to proceed without freezing. Remembering the other three games, I speculated that perhaps these games were being blocked by my original VMU because it had created a kind of barrier to memory access.

Inexplicably, to my amazement and relief, all four games became unblocked and started without any issues!

From what I understand, this glitch if happen it seems to “nests” somewhere in the Dreamcast's memory, data bus or RAM (?!). Resetting the Dreamcast doesn't resolve the issue, and it's not directly tied to the VMU because, without the VMU, the games would still freeze. Instead, it requires a different electrical stimulus related to data transfer on the bus to unlock the error or glitch that occurs initially with these listed titles. If this glitch occurs, it may also affect other titles that rely on VMU control during boot if the VMU's memory is filled with save data. I'm not sure if a different VMU is needed to resolve this glitch, but using a different freshly formatted VMU takeout the glitch and certainly does the trick. Even if you switch back to the original VMU that caused problems before, the glitch doesn't reappear because there seems to have been a "reset" of the error. However, it's advisable to run these listed games with a VMU that has free memory space to avoid encountering this problem on the VA0 Japanese model.

I hope this guide and information help others who, like me, have scratched their heads and nearly gone mad trying to find a solution.

[fafadou]

Dragoncity had better result with vmu for evil twin and ooga booga. Check in his list.

do you have cdda for those games ?

[CrisMod]

(02.11.2023 13:32)fafadou писал(а):  Dragoncity had better result with vmu for evil twin and ooga booga. Check in his list.

do you have cdda for those games ?

Hey fafadou , the issue here doesn't hinge on which settings one uses or doesn't use. In this guide, I delve into the root cause of the problem. Game testing on my end has been flawless, and they all run smoothly, so that's not the main focus of this guide. Instead, we're here to investigate and uncover the other issues that VA0 JAP users might come across and where they should look for a solution (believe me, I've conducted more tests in recent weeks than I can count). Now everything is functioning well, particularly after eliminating the glitch that was exclusive to VA0 JAP.

The settings for Looney Toones now are exactly the same as yours, and now the game can even start with any other configuration as well. The remarkable thing is that this particular glitch on VA0 JAP that I encountered in this game is truly astonishing.

[Freudi93]

Which VMU so you usw? I have original JP VMUs there from the beginning of dreamcast sells in jp. They make a longer Peep Düring booting of dreamcast

Also i have a Memory Card there with 4 save Slots and a MadCatz 1MB VMU

Also i have 3 dreamcasts for Testing there:
-Dreamcast Va1 PAL with G1ATA with noctua Mod and PicoPSU
-Dreamcast Va0 JP with GDAta
-Dreamcast Va0 JP with dcdigital HW2, Fan Mod and Pico 130 Watt PSU

Is there something i could Test?

[pcwzrd13]

Interesting results but I'm not able to reproduce them with my own JP VA0. Tested both Looney Tunes and Soldier of Fortune with a few different VMUs (one with only 6 blocks free) and both booted fine.

[CrisMod]

(02.11.2023 16:04)pcwzrd13 писал(а):  Interesting results but I'm not able to reproduce them with my own JP VA0. Tested both Looney Tunes and Soldier of Fortune with a few different VMUs (one with only 6 blocks free) and both booted fine.

You need full VMU, but even if you are going to do completely full the VMU could be that it's not a roule that appear to you, this story it's like the Tomb Rider Chronicles story , there is not a specific roule of those things.... But could show, maybe some currepted datas when it's the VMU it full without any block free or what so ever or the position of the "Moon" ....anyway if appear to someone here there is the solution to erease this kind of glitch.

[pcwzrd13]

(02.11.2023 17:16)CrisMod писал(а):  You need full VMU, but even if you are going to do completely full the VMU could be that it's not a roule that appear to you, this story it's like the Tomb Rider Chronicles story , there is not a specific roule of those things.... But could show, maybe some currepted datas when it's the VMU it full without any block free or what so ever or the position of the "Moon" ....anyway if appear to someone here there is the solution to erease this kind of glitch.

Yeah, even with a completely full VMU, they still boot up fine for me. There must be something very specific about your setup that's causing it. Weird.

[CrisMod]

(02.11.2023 15:41)Freudi93 писал(а):  Which VMU so you usw? I have original JP VMUs there from the beginning of dreamcast sells in jp. They make a longer Peep Düring booting of dreamcast

Also i have a Memory Card there with 4 save Slots and a MadCatz 1MB VMU

Also i have 3 dreamcasts for Testing there:
-Dreamcast Va1 PAL with G1ATA with noctua Mod and PicoPSU
-Dreamcast Va0 JP with GDAta
-Dreamcast Va0 JP with dcdigital HW2, Fan Mod and Pico 130 Watt PSU

Is there something i could Test?

Thank you, Freudi93, and you've got an impressive list of machines as well .

No, you can't test this issue here because it may occur under a specific set of circumstances that must intersect. Firstly, it requires a completely filled VMU with 0 datas, then there might be some corrupted data within the VMU, along with other contributing factors. Collectively, these factors create a sort of glitch in the system, where a limited set of games check the availability of the original VMU and then interact with it to display the game image on the VMU screen. When the data doesn't pass through correctly, it results in a black startup screen. Even if you remove the VMU, the data remains frozen somewhere, causing the block. To resolve the situation, you need a second empty VMU to provide an electrical stimulus to the system and unlock that glitch.

So, don't worry if you haven't encountered this issue, and if you have more than one VMU available, you're in the clear.

---

(02.11.2023 17:27)pcwzrd13 писал(а):  

(02.11.2023 17:16)CrisMod писал(а):  You need full VMU, but even if you are going to do completely full the VMU could be that it's not a roule that appear to you, this story it's like the Tomb Rider Chronicles story , there is not a specific roule of those things.... But could show, maybe some currepted datas when it's the VMU it full without any block free or what so ever or the position of the "Moon" ....anyway if appear to someone here there is the solution to erease this kind of glitch.

Yeah, even with a completely full VMU, they still boot up fine for me. There must be something very specific about your setup that's causing it. Weird.

[Freudi93]

Other question: so you have cdda Sound Problems in your va0 Dreamcast

I have so many because i bought Orten Games with dreamcast console in bundel and i spend to much Moby in dreamcast collecting

[CrisMod]

(02.11.2023 18:23)Freudi93 писал(а):  Other question: so you have cdda Sound Problems in your va0 Dreamcast

I have so many because i bought Orten Games with dreamcast console in bundel and i spend to much Moby in dreamcast collecting

No, about the sound I'm fine with all the games, except (for now) as I remember the Re-volt title, if I don't activate the CDDA I don't have the background music; but all the rest of sound Menu signal and ingame sound are working fine. If I activate the CDDA in Re-volt the backgorund shutter, but to say for sure i need to test it more deeply. I did't have time to play around with it because was a small problem for me.

And another game that was problematic about the sound and I fully solve it was Unreal Tournament.

Why which games do you have those problems (make me please a list with a short description of the problems), maybe I will re-test for you and get you back later with resaults and settings.

[Freudi93]

Yes this is axectly the Problem i have. Also dave mirra freestyle bmx
Quake 3
Railroad Tycoon II - Gold Edition
Sega Gt
Toy Racer
Toy Commander

Have same Problem

[CrisMod]

(02.11.2023 21:52)Freudi93 писал(а):  Yes this is axectly the Problem i have. Also dave mirra freestyle bmx
Quake 3
Railroad Tycoon II - Gold Edition
Sega Gt
Toy Racer
Toy Commander

Have same Problem

Hello Freudi93,

I've tested the games you listed:

1. Dave Mirra Freestyle BMX
2. Quake 3 Arena
3. Railroad Tycoon II - Gold Edition
4. Re-Volt
5. Sega GT
6. Toy Commander
7. Toy Racer

I conducted numerous tests using Loaders that support CDDA, and I even tried the physical disc as an additional test. Based on the tests I performed, I can confirm that when CDDA is activated (in those listed games), in-game music exhibits crackling while all other environmental and graphical sound effects work well.

If CDDA is deactivated, you can hear all the graphical, environmental, and menu selection sound effects but not the background music (or a part of it). I might have figured out why this happens, and I'll try to explain it in simple terms (here, @SWAT may either confirm or refute this theory).

This issue appears to be related to how the game handles music, which is loaded kind of separately from other in-game sound effects and environmental audio. When CDDA is active, will force to load the background music but isn't entirely loaded into RAM with the game and rather fetches data continuously, communicating with the SSD/CF/HDD, and so on. In fact, I observed that the background music, being somewhat separate from the game's effects, in certain games that require more RAM and almost fill up the entire RAM space, there isn't enough room to accommodate the Loader along with all the game's assets. With the physical disc, everything works normally because it utilizes the hardware without "emulating" the GDROM.

Therefore, it seems that with CDDA active, the background music is constantly loaded and unloaded in small blocks (as the rest of the RAM is occupied by DS Loader, preloaded scene textures and so on) within a limited RAM space. This is because some games consume nearly all available RAM, and in terms of development, I believe that @SWAT faces a significant challenge. What he has achieved so far in managing all of this within hardware with precise resources (for certain games) is truly outstanding.

In games that don't consume all available RAM, the background music with CDDA enabled sounds fine. However, in cases where a game has heavier 3D graphics and consumes more RAM, there's less space available for CDDA to load additional background music that is separate from the game. Consequently, when there's limited space, the Loader must constantly load and unload data into RAM, fetching data continuously from the IDE, which leads to those annoying audio crackles.

It seems reminiscent of when, a few years ago, I created Sonic 64 for Dreamcast using the Mario 64 image, where the Nintendo 64 textures consumed most of the RAM. To overcome this, I had to consider a possible RAM upgrade, increasing it from 16 to 32MB.

[SWAT]

For the PCM track, all the RAM is not enough; you need 3 times more. Therefore, the data is read and played in small portions. If you experience clicking during playback, try changing the location of the heap.

[CrisMod]

(05.11.2023 16:09)SWAT писал(а):  For the PCM track, all the RAM is not enough; you need 3 times more. Therefore, the data is read and played in small portions. If you experience clicking during playback, try changing the location of the heap.

Thanks @SWAT, that's what you said because it confirms what I suspected .

I'll try to play a bit with the HEAP as you told me....
@Freudi93 try from your side as well,please !!!

[Freudi93]

Yes i will try. Have you some tips how to begin? With heap you mean the 0x8..... address?

Should we start a new Thread? For better traveability?

[CrisMod]

(05.11.2023 19:19)Freudi93 писал(а):  Yes i will try. Have you some tips how to begin? With heap you mean the 0x8..... address?

Should we start a new Thread? For better traveability?

Done: `http://www.dc-swat.ru/forum/thread-4042.html`.