Gameboy Color Boot ROM Dumped After 10 Years

An anonymous reader writes "Costis was able to dump the elusive boot ROM from the Gameboy Color by using various voltage and clock glitching tricks. The boot ROM is what initializes the Gameboy hardware, displays the 'GAMEBOY' logo and animation, and makes the trademarked 'cling!' sound effect. Even decapping the CPU had failed previously, but now the boot image and specifics on how it was dumped (along with many photos) are available for download."

Comments

Re:Cool

[Xeon3D]

I really love reading about the lengths enthusiasts go to when trying to do this kind of thing. For some reason I had assumed that this had been done already since there is already emulation for gameboy color, right? Can someone explain the significance of this development?

The gameboy bios was also "emulated" before, so this makes the emulation more "realistic". It happens the same with the GBA. While you can emulate games for the GBA without the need for a BIOS file, if you have one, they'll run better \ more accurately (or in some cases, they run instead of not running).

Re:Cool

[noidentity]

This allows Game Boy Color emulators to display an authentic intro before running the game, including the palette selection available when running a non-color game. There's otherwise no benefit that I can see. This includes initial register values, since those could already be determined via software. Some of the other initial state, like sound registers set by the boot ROM, is more difficult to determine, so this helped there.

When reverse-engineering hardware, it's nice to figure out every detail, and this was one of the much harder ones to figure out. Decapping usually reveals all, but even that failed here.

Re:Why can you not just read the rom??

[noidentity]

Why can't you just take the rom chip out of the gameboy, put it in a socket on a computer and just read the rom 1 byte at a time?

Because the boot ROM is built into the custom CPU. The data bus to this ROM isn't exposed on any of the pins; when enabled, it bypasses whatever is being sent to the external data bus pins on the CPU, so that its contents are never seen by the outside world.

A close comparison is the L1 cache inside a modern CPU. When the CPU is reading from it, you can't know what is in it, since the data isn't output to the bus.

Re:I smell double standards

[Mr Z]

I assume you refer to the United States. The US was actually late to the party. The Berne Convention got the ridiculous-copyright-term ball rolling... Disney just gave it an extra push. In particular:

The Berne Convention states that all works except photographic and cinematographic shall be copyrighted for at least 50 years after the author's death

The Berne Convention is also what gives us the rule that daid303 stated, that you don't need to add a copyright notice to get copyright:

Under the Convention, copyrights for creative works are automatically in force upon their creation without being asserted or declared. An author need not "register" or "apply for" a copyright in countries adhering to the Convention. As soon as a work is "fixed", that is, written or recorded on some physical medium, its author is automatically entitled to all copyrights in the work and to any derivative works, unless and until the author explicitly disclaims them or until the copyright expires. Foreign authors are given the same rights and privileges to copyrighted material as domestic authors in any country that signed the Convention.

The US didn't sign on to Berne until 1988. The EU's been on board for awhile, as have many, many other countries. So, yes, you're technically correct that there are some people that are unaffected by the US's copyright protections (or in the case of Nintendo's IP, Japan's). But, a great many places have similar restrictions.