ROM Hack Custom Bios

[gudenau]

I have a question, could you make a custom ds bios, and if so could you point me in the direction of the information to do so?

 

[Rydian]

Why?

 

[xdpirate]

Why?

Nice one word post, bro.

On-topic: There are no tools to modify the DS firmware. Even if there were, there is no way to get it back on the device, the FW is read-only.

 

[Rydian]

Nice one word post, bro.

It's a serious question. There's already firmware modification tools/techniques to do things like remove the health&safety screen, etc.

On-topic: There are no tools to modify the DS firmware. Even if there were, there is no way to get it back on the device, the FW is read-only.

Lite can have part of the settings overwritten causing it to skip screens, and you can always replace the chips on the motherboard (like some people do for NES ROM hacks, transferring to original carts.

 

[Foxi4]

Uhh... guys? FlashMe? That's probably all the OP needs, unless he'll specify what kinds of modifications he's interested in.

On-topic: There are no tools to modify the DS firmware. Even if there were, there is no way to get it back on the device, the FW is read-only.

Yes, you can install a modified DS firmware and yes, it has been done before as seen above. Not sure how the modifications were done, but I'm assuming that via painstakingly fiddling with the original firmware in a hex editor or a similar tool which makes it pretty difficult for us, mere mortals.

 

[gudenau]

I have a few small to medium tweeks that I want to make myself, starting with somthing like skipping the health screen, like flashme, but it would be for learning.

 

[Foxi4]

I have a few small to medium tweeks that I want to make myself, starting with somthing like skipping the health screen, like flashme, but it would be for learning.

Let's just say that this is not something you'd want to screw up, so unless you have the hardware capable of flashing your system in the (likely) event of screwing up the firmware modification, you'd have means of fixing it. Moreover, you need something to dump the firmware with, unless you find a copy of it floating on the Internet.

If I were you, I'd contact the FlashMe team and ask for pointers.

 

[gudenau]

I know, I would test with an emulator, as some support it. I do know that could cause my dses internals to implode.

 

[Foxi4]

I know, I would test with an emulator, as some support it. I do know that could cause my dses internals to implode.

Keep in mind that emulators are not 100% accurate and often ignore errors. Only testing on actual hardware gives you the full picture.

 

[gudenau]

I know these things, why else would I be treing to learn low level stuff like this?

 

[Foxi4]

I know these things, why else would I be treing to learn low level stuff like this?

Alright, chill. In that case, you'll have to Google for resources on how the DS works, what are all the registers and calls the hardware does and so-on and so-forth.

http://nocash.emubase.de/gbatek.htm

This is a very accurate resource but even this contains some errors, so you'll have to double-check with similar collections. It was made by NO$GBA's creator and it was one of the cornerstones of DS Homebrew development - it should give you at least a vague idea about how the system works. Once you know the ropes, you can start trying to modify stuff in the firmware itself.

 

[gudenau]

I will take a look, I look at this so often I am supprised I have not memorised the hole thing...

 

[Sicklyboy]

Uhh... guys? FlashMe? That's probably all the OP needs, unless he'll specify what kinds of modifications he's interested in.


Yes, you can install a modified DS firmware and yes, it has been done before as seen above. Not sure how the modifications were done, but I'm assuming that via painstakingly fiddling with the original firmware in a hex editor or a similar tool which makes it pretty difficult for us, mere mortals.

And for a more total, but less complete replacement, I present to you FW Nitro.

It's doable. It's very doable. But nobody really gave the time to really put work into it.

 

[FAST6191]

First BIOS and firmware are not the same thing on the GBA and DS- the BIOS does have a bunch of functions useful in system general and general operation (we call them BIOS compatible compressions for a reason) and to the best of my knowledge they (DS ARM9, DS ARM7 and GBA) are stored on a ROM chip. Possible hacks aside (and given we have total control over the DS it is pointless) I do not see the need to overwrite the BIOS.

The firmware on the other hand is somewhat rewritable though on the DS and DS lite there were no real projects aimed at incremental updates. The three mods were
Flashme - a hacked version of the original BIOS to remove RSA checks on download play components, allow force booting of GBA or DS slots (there was a time where the DS slot stuff was not properly understood), a little bit of PWM to vary the brightness level on boot and for some original models of the DS that had the lite's variable brightness chip for them to have variable brightness. Arguably the one most people used.
Loopy's minimalist firmware. Basically what it says and was the minimal thing needed to boot.
FW Nitro - the only serious attempt at a proper modded firmware as far as I know, kind of geared towards GBA slot stuff so not really so workable today where everybody mostly used DS slot stuff. It should be open source though so you might gain something- http://fwnitro.caitsith2.net/

Tools of choice
http://nocash.emubase.de/gbatek.htm#dsfirmwareserialflashmemory and the docs at large.
Noflashme is the software method of rewriting the firmware but you will want a hardware one too and http://www.darkfader.net/ds/ has you there (page search ppflash - you will need a parallel port).
Finally the original DS firmware is a hodge podge of many different compressions, encodings and whatever else (for example it uses BCD at points) so you might want a nice tool to unpack the lot. One unpacking tool- http://forum.gbadev.org/viewtopic.php?t=12270 , it does not repack it but source code it there and the compressions are well understood.
There are a handful of tools that can also edit the DS firmware dumps to change names and whatever else (I tend to use crystaltile2 myself).

 

[gudenau]

Thanks guys.

 

[The Catboy]

There are few custom firmwares, that I know of.
Flashme: Pretty much the same firmware as the normal DS Phat/Lite firmware, just removes the safety screen and adds an autoboot for NDS-Mode for slot-2 cards.
FWNitro: A rather simple menu, some features don't work and it doesn't work with 90% of the flashcards out there.
CreeboMe: Only comes with 3 options, boot into slot 1, boot into slot 2 NDS-Mode, Boot into slot 2 GBA-Mode
HBfirmware: Same as CreeboMe But even more simple.