Custom BIOS goes to version 1.031!

Hi there,

I have been working quite a long time on that version. And not necessarily on the features that may sound hard. Changing from white to black the fade-in color when booting a GD-ROM took me a couple of hours. I was looking for something that does not exist in the code so that kinda explains why ๐Ÿ™‚ That version is intermediate in the sense that I needed to be sure that backups can boot without a system-reset before going any further in my research. Now that I know it is possible, many things are worth considering in the next versions. The first things that come to my mind are the extra region protectionsย  games can have (RGB/PAL protection, system broadcast check, etc.) then a in-game-reset that is working in all games. Finally, I am considering working on the bleemcast issue. As far as I know, it’s the only game that does not like my bios….
Oh, yeah, speaking of that, I really need support. All my GD-ROM drives are broken and I need to get a new one. I would also appreciate if someone could make me an offer for a black Dreamcast, with its box. I am looking for an almost-new one (scratch-free). The US Sport Edition would even be better ๐Ÿ™‚ Well, it’s time to let you download the “stuff” and enjoy it!

New features (for a long description, see the readme file):

  • SEGA License screen skip
  • MIL-CD/backup direct boot
  • Black fade-in color while booting from menu
  • No VMU copy-protected file check


And for those that don’t really what I am talking about, I made a short video:

Update #1: someone gently reported that once a GDRom has been detected by the console, no MIL-CD/backup can boot up. GDEmu and UGC are fine though since they do not emulate the drive lock protection.I did not know that, so for now, until I’m able to test and either fix or disable the direct-boot feature, I remove the download links. Thank you.

Update #2: The next version V1.032 is almost ready. I’ll put a release note about the MIL-CD issue you can experience. In the meanwhile, as some people asked, I put back the link to download the v1.031 release.

28 replies on “Custom BIOS goes to version 1.031!”



0GDTEX.PVR can not be displayed in the BIOS screen๏ผŸ

adn Can you show the PR and PC values in a corner of the screen?

RE: kof888

0GDTEXT.PVR can be displayed, it is just, as always, a matter of time of implementing it… I haven’t work much on that patch but it is still planned for future releases. If I can display the values, yeah probably but I am not going to release a bios what. What would you want to do with that??

RE: kof888

Thanks for your reply…

I just want to debug some of the games I have modified on the real machine, and those games have no problem with EMU.

Re: kof888

You would then need more than that then, like being able to set breakpoints and stuuf like that. If I display some registers values on the screen I don’t think you’ll be able to catch the values since they change pretty fast ๐Ÿ™‚

RE: Re: kof888

No, the game is not possible on a regular host.
I know the registers will change very quickly, but I will set some traps.
Thanks for your reply

Thank you!

Just flashed your bios and it works great. It feels like a real upgrade and not just for aesthetics. Can’t wait to see what else you have in store!
Also, do you think it would be possible for it to automatically load the 3D bios screen like the one here:

Hello Good Work ^^

I would like to change my original Bios Dreamcast Japanese with your Custom Bios

I want to know if your bios bios and also a red color like Japanese Dreamcast Dev Kit ?

and what is Method for flash a bios of dreamcast ?

Thank You for answers
Best Regards James ^^

So you have to know that the boot-anim color is not stored in the bios but read from a read-only partition located in the flash chip. Flashing the dreamcast with a new bios is not going to change that, at least not with my bioses (for the moment).

To flash the bios, I would recommend you to follow this tutorial:

To change the boot color to red or black, the only solution for now is to make the read-only flash partition that contains the factory settings writable then booting up the dreamshell disc and launch the Region Changer app:

Hope it helps ๐Ÿ˜‰



How is possible to add your Bios to Dreamshell disc? I’m trayin using UltraISO and adding to the Bios folder but when I create the CDI again using DiscJuggler my GDEMU can’t recognise it.

Thanks for your hard work.


Good job on thoses bioses! I’ll sure check out how it works in conjunction with gdemu!

If I can make a suggestion, would it be possible to skip the set date/time prompt when booting with a dead battery, and have it automatically set to the default date instead? Not a big deal, but it’s a bit annoying to always set the date if you haven’t played in a while. The date is very unimportant for the vast majority of games and I know I always end up simply selecting the default date to play asap.




I remove the download links since there is a bug with the “direct-boot” stuff I may not be able to fix… anyway it works fine with a gdemu or ugc.
So yeah, about the date, someone also asked to the update the default date to a newer date, like 01/01/2015. I’m gonna work on that for the next release and try to make the “set datetime” window optional. Thanks for your input, I appreciate.

Best BIOS Ever!

Updating the Time & date sounds great, I think it be best if the new date is the data of the newer BIOS. (Ex: 08/26/2015 for 1.031)

Also the direct-boot thing is a great idea and is very helpful for the DC’s Laser Lens. It may have a bug in it that can’t be fixed but its great to look at my VMUs then start-up a MIL-CD of something like Lost Hope once I know I have the right VMU save. (Saving on Boot time and laser lens ware.)

I love this new BIOS you’ve made and I offer it for all the Dreamcast units I mod. (letting them know of the little bug before adding it.)

Thanks and can’t wait to see what will be in the next var. (If I can think of anything useful, I’ll be sure to let you know.

RE: Best BIOS Ever!

Thank you for your feedback.

So you’ll be happy to see that the next will make your life easier regarding the set datetime thing ๐Ÿ˜‰

Btw, how much you charge for doing the DC mod? Gonna ask you some royalties lol!

I want to offerta you a beer

I m gonna do the dual bios mod on my dreamcast, and your bios is my choise!!! Great work…wish you wil improve this bios more because it would be something awesome. Can i donate something to you via paypal? I can t offer you a dreamcast cause i have two (white pal) but the one I m gonna mod is the one i will dual bios+vga+sd and the other is untouched for my collection, so maybe I can start the first of the donation to buy you a dreamcast… I mean the black one sport it s pretty cheap, a good one on ebay will be no more than 100โ‚ฌ or dollars. It s an easy fundraise to complete and a thanks to your work. 1 dollar all the people that use your bios and it s done in a day

For a future version, could you have the blue PAL swirl boot with an option to have the second ‘Produced/Licensed by Sega’ splash screen? I like the direct MIL-CD boot, but i also like the second splash screen. What might be neat is having a black background on the ‘Produced/Licensed by Sega’ screen. I’ve been looking for a region-free bios with the blue PAL swirl boot. But anyways, nice project

This bios is region in case you are asking. Regarding the the splash screen (license screen), starting from the next version you will have that option to either enable or disable it. Not for the color though. I’ve a lot of other things to do :/ But there will be some other customization things ๐Ÿ™‚

Emulator use?

Hey, I want to use this in an emulator, but I need a matching dc_flash.bin. Should I use a stock one? If so, which? If not, what do?

RE: Emulator use?

Hi, so yes, any emulator requires a copy of the system’s flash memory. Any “dc_flash.bin” should be fine. My bios is based on the retail 1.01d so just download an emulator pack with the dc_boot.bin & dc_flash.bin then just replace the dc_boot.bin with my bios. Otherwise send me an email and I send you a factory dc_fash.bin.

RE: I want to offerta you a beer

Thank you Alessio! I appreciate your interest for my work ๐Ÿ™‚

The problem with the black dreamcast I find, they always have scratches, in not so good condition :/

I’ve been thinking about a fundraising, or more precisely a monetary compensation for my work. I’m probably going to do so starting from my next release. I will tease the next release then when the donations are high enough I release my soft. I think a couple of $ or โ‚ฌ is really nothing compare to the time spent. Anyway if you come over and buy me a drink, you don’t have to donate ๐Ÿ˜‰

In case you want to support my project, you can donate via paypal: here

Thank you again

Well i tried your paypal link to donate as I wss the one on assembler you sent the bios to my email when it was pulled. Anyhow I just tested your Dino Crisis patch and the first video works but the rest do not. The video is garbled. Reguardless i want to donate as i truly appreciate your work. If you still have my email send me a link so i cant send you $5+ or so. If not any link here will do. Keep up the grest work.

This bios can works with g1 ata mod?

Hi japanese cake i have a question for you, is possible to integrate this mod for the hdd mod of sega dreamcast?
I want to grow up the compayibility if the dreamshell due the shenmue 1 not works on the g1 ata mod, i need your help in order to fix more games and make in a near future a better version of dreamshell and run more games.

Re: This bios can works with g1 ata mod?

That’s a good idea! I have not real idea whether I could do it as I don’t own a g1 ata mod. If I get one and I can get technical details/help, I think I would at least try to implement it ๐Ÿ™‚ Right now I’m struggling with a silly bug for my next release… It is like having something done at 99% and wasting my time fixing the last percent.


Hello japanese_cake,
Great job with the boot rom, amaizing :).

Just one question, Does the devkit version of your bios initialize properly the SH4 UDI subsystem so the Dreamcast can be debugged via JTAG?. It’s because I’ve attached one to my console, but with the retail boot rom apparently it’s impossible to do it.


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