Release: Custom BootROM v1.032

Hi there,

A couple of months ago, I thought I was ready to release my new bios. Unfortunately for me, at that time, I was really busy and my bios mod started to show weaknesses. As I don’t have the right soldering equipment, I had to work with my Dreamcast and all its little faulty contacts. I worked hard to get the reset exception working correctly… actually way more than I should have! The reason? On my Dreamcast, the faulty contacts I mentioned were crashing the Dreamcast upon reset! I took me quite some time to figure this out :/

That was quite unfortunate for me but at least it gave me the opportunity to have a glance at other things. I explored a bit how the region protections games like San Franciso RUSH 2049 have and came up with a solution that fake the system region. Later I decided to force the video signal to output a 60hz refresh rate (more details in the readme file) and so on and so forth. So now the bios I’m releasing today is way more advance than I planned initially.

With the holidays coming, I don’t want to hold it any longer. However I prefer to warn you beforehand: even if I tested most of the features, I can not guarantee that everything is 100% working (and constructive feedback is welcome). I am sorry for this but no worries, the bios does not contain some kind of bad-ass code that could destroy your Dreamcast πŸ˜‰

I tried my best to add new features, improve compatibility with some naughty retail games. But it comes with some drawbacks: no cheat disc until I release one compatible with my bios, some independent games like Pier Solar do not work anymore (again, more details in the readme file). I will address those problems later. For those using GD-Emu, you are probably also using the GD-Menu app Neuroacid created. Well here again it doesn’t work anymore, but soon a compatible will come to light! By the way, kudos to neuroacid who saved me time and helped me a lot for the testing!

Ok, that’s enough talking for now, let’s check the features out:

bootROM v1.032 Retail & DevKit Changelog:

  • In BIOS menu to update the following bootROM settings (Boot animation color, SEGA license screen skip, MIL-CD/backup direct-boot, Dreamcast main menu scenery perspective and color)
  • Skip the “set date/time” screen
  • BIOS video mode forced to 60hz
  • Auto region patching for GD-ROMs
  • Internal changes for future updates

Please read the readme file to see the complete list of features.

Download link (contains retail & devkit boot anim):

  • jc-bootROM-retail-v1.032.bin SHA1: ec42875983f33cefafe8616eb9152cf0172136ae
  • jc-bootROM-devkit-v1.032.bin SHA1: b5b00b3a34d6556abb34450d0fb9d37a57d7dd05

See you soon!

45 replies on “Release: Custom BootROM v1.032”

Dreamcast GOD MODE!

Some error or not, this is most likely your best BIOS so far “Skip the “set date/time” screen” you just saved lots of time for people who hate the battery going bad or just runs out of power if it was off too long.

Auto region patching & Forced video mode are great add-ons to have as I’ve seen some error like this before using a Japanese Dreamcast & playing USA games on it. (only like 2 games)

Great work as before, hope to see more in good time. Maybe you can fix Pier Solar’s compatible, or just have a dual BIOS setup & use the old one for that.

Oooh I spoke too soon, it just can’t boot games. πŸ™‚ Look forward to the fix but until then great work as always!

So yes GDMenu boots but as the structure of my bios differs a lot from the original ones, it does not copy the right part of the bios to ram when it boots up a game. I have the same issue with the cheat disc, more or less. Fortunately this issue can be fixed. Neuroacid and I worked together and were able to get it working. Neuroacid is planning to release a new version but as we all are busy working on other things, you have to wait a little bit πŸ˜‰


milcd: yes
pirated gdrom (backup): yes
homebrew: yes for those that do not reply on some data chunk to be present in the bios, no for retail indi games (but yes for those that got their copy protection removed, like the cdi image of Sturmwind floating around)

Thanks for the pointer but I already read that πŸ™‚ (didn’t know that was used in bleem though)

MIL-CD Error or is it just me?

I’ve loving this new BIOS a lot, like the dark blue 2D menu the best so far. It just gives a much newer look to me.
I think the Auto region patching is helping my Japanese Dead of Alive 2 LE give me English subs as before this BIOS update, I never seen any.

It may just be me but I think something may be wrong on the MIL-CD/Backup end as I can’t same to get any MIL-CD to work at all, from home made to retail game like Sturmwind. All of them start no problem… but don’t go pass the license screen or just a black screen if the License screen is off.

Maybe this is a know error and I just miss it on the readme, if so sorry for posting this comment. Also this is a VA1 model, I’ll be trying a VA0 soon.

RE: MIL-CD Error or is it just me?

Hi, thank you for your feedback!

Most retail independent games (like Ghost Blade, Sturmwind, Pier Solar, etc.) have copy protections that rely on certain data being present in the bios. As this bios has totally different structure from the retail one, those games fail to boot. You can find some of them on internet that have their copy protection stripped off (This is the case for Sturmwind). Such games work fine with this bios πŸ˜‰

I am sorry not to be able to ensure a better compatibility with those games but so far no body has found a way to create a modified bios that passes the dreamcast protection I mention in the readme. Otherwise, life would have been way easier for us!

RE: MIL-CD Error or is it just me?

Thanks for the reply, By the sound of things this is how most if not all MIL-CDs are setup so I think I going to re-mod my Dreamcast to have a Dual Flash BIOS setup to use both your newer v1.032 & older v1.031 on one unit.

Lot of Game doesn\’t works ?

Hi Japanese Cake, first thx u for your work, it’s an important step for the DC community. I try your custom bios yesterday, but lot of retail games and private copy doesn’t work ??
The game boot and instantaly come to the menu screen. Do you have the same thing ?

I use my GD rom to read games



Thanks for this great bios!

My second Dreamcast with USB-GDrom installed has boot problems with it.
It boots, but can`t read the files from the hdd. Can`t figure out what the reason is…

Boot loader

Hi buddy, you make a very good job !!!! i like your japanese cake. One question can u put in the .bin the DC loader for ide emu ?

Time/Date Boot Loop?

I’ve just setup a dual BIOS setup using the Sega Retail & your bootROM DevKit v1.032. As I was testing it I now see that using both may (as it may just be me) make a boot loop on the retail BIOS looking for the Time & Date all the time, It does it two times before you get to the menu & if your trying to boot a MIL-CD it loops over and over.

If you use 1.032 if does not do the loop.. most likely thanks to the Skip “set date/time” screen you added. The only fix I can see is by removing the Time & Date’s CMOS battery & give it some time and add the battery back, then do set any of the setting for like 3D Menu, etc.

I’m thinking it may be from how the new bootROM known what setting you set. As this unit is not for me, I added the older v1.031 for safety.

RE: Time/Date Boot Loop?

Hi, thanks for your feedback.
I am not sure I understand everything though. What is the time issue with this release exactly? Once you have skipped the “set date/time” screen with the custom bios, if you switch to the retail bios with a milcd, the bios keeps asking forever to set date and time?

RE: Time/Date Boot Loop?

Yes that is what is was doing, however I don’t think it was the BIOS itself at all as I’ve done the same setup to more units & I’m starting to think it maybe just some hardware error on that one Dreamcast or maybe a cap or something like that going bad.

Love to see what you do next, Great Work!

Hi, awesome work! I’ve just installed v1.032 today on my va1 pal dc

Loving the customisations for the swirl and original games from all regions are booting and playing fine. I am however having issues with backup games. They are detected and boot but the image isn’t right. They are shaking and seem to overlap. I’ve tried a few different games. If I drop back to v1.031 or link83’s bios the same games boot and play fine.

Any ideas?

Congratulations and thanks for your hard work!
I wanted to ask if it is possible to add an option to boot Dreamshell since the original Dreamcast bios (in this case your bios) to use the original console interface. E seen that with the upgrade Sonic Team (Puyo Puyo Fever) may execute files and read a PVR, and also whether it is possible to customize these images.
Thanks for everything.

Thank you for your support, I appreciate!

Booting Dreamshell is part of the feature I would like to add. For the moment this project is on hold as I don’t have much time and I spend it on VGA patches. Moreover, there is the protection that is sadly putting strong constrain on the development.

The Puyo Puyo Fever “hack” is no more than a hidden bios feature that reads and loads a PVR file off the VMU. My bios only unlock it the “free-camera” thingy. The PVR background is totally customizable though. Check this out here –>

I love your work, but i live in Denmark and have PAL consoles…
If you could make a version of the bios that dosn’t include the “forced to 60hz” mode, you’d make my dream come true (and propably others too)… right now i’m forced to use the older version, ‘cos the newest really dosn’t work well with a PAL console, games and tv…

Best Regards

Thank you for your message. I appreciate the feedback. Forcing the 60hz was kind of a last minute patch I thought would be nice to have but I didn’t know it would an issue. Anyway, the next version will offer a selector to force or not the 60hz πŸ™‚

APAL version?

Can you please make a version without the “force 60hz” for PAL consoles and collectors?
I currently use your old one, cos that feature is just not a good combination with a PAL DC, TV and game collection…
O’m no expert, but i gues it wouldn’t be a lot of work to disable that one thing (if i knew how i’d do it myself ‘cos the rest of it is great 😊).


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.



Hey, I have a little problem, This will works on Reicast Dreamcast android emulator?

I have a problem, please help me >β€’<


I just see an update in the dreamshell dcswat website.

It’s written update 1.032 japanese_cake bios. Do you know what is it ?

Not working in Reicast

Do you have any idea why this is not working in Reicast? I would love to use this BIOS for Reicast on RetroPie because that build has a long standing bug where the date and time are not saved and must be entered at every launch. Every time I try to launch Reicast in RetroPie with this BIOS it looks like it starts to load then it kicks me back to the menu. I also tried it under the bleeding edge Windows builds and I get a strange error message:
I know you don’t have anything to do with Reicast but I hope you can provide some insight.

Not booting Mil Cdrs?

Hi. First of all wanted to say thank you for this really great bios. I have used 1.031 in the past and thought I’d try 1.032 but for some reason everything seems to be working but it wont boot up mil CDs. Not sure if gd-roms boot as I don’t haven any currently to test, looked everywhere.

Not working in Reicast

I posted this before but for some reason it was marked as spam.

Do you have any idea why this is not working in Reicast? I would love to use this BIOS for Reicast on RetroPie because that build has a long standing bug where the date and time are not saved and must be entered at every launch. Every time I try to launch Reicast in RetroPie with this BIOS it looks like it starts to load then it kicks me back to the menu. I also tried it under the bleeding edge Windows builds and I get a strange error message:

Verify Failed : data==0 || data==0x001fffff || data==0x42fe
in sb_write_gdrom_unlock ->
C:\projects\reicast-emulator\core\hw\holly\sb.cpp : 136

I know you don’t have anything to do with Reicast but I hope you can provide some insight.

Re: Not working in Reicast

I think they put an assertion in their code that ensures the bios does the “right initialization” and but in here reicast expect that the bios writes the value 0x0 , 0x001fffff or 0x42fe into a holly special register (0xa05f74e4). It is true that all retail bioses use those values. Unfortunately mines and some other “special” bioses use differente values, causing this exception in the code. Maybe you could open a ticket in their github page.

Dreamshell bootloader

Hi does this have the bootloader to enable booting straight into dreamshell from IDE?


Won’t read backups

So I’m having issues with this BIOS release, in that it’s very picky with the backups it chooses to read. Dreamshell loads fine from a disc, but Ecco hangs on the license screen and won’t go any further. What’s even more interesting is that 1.031 works fine with that same Ecco backup, and even more bizarrely, I have even tried 1.032 on a different DC of the same board revision (VA1), and that booted Ecco with no problems at all.

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