NES cart dumping/plug-in

[Pickle]

What about an approach that has been done with the kazoo/unagi?
As I understand it a script describing the attibutes of the mapper/chips is fed to the unagi application which through the kazzo hardware dumps the contents.

http://sourceforge.jp/projects/unagi/wiki/kazzo_intro_en

[ICEknight]

Just wondering, is it impossible to just dump everything that's found within each cartridge?

I know the PRG and CHR dumps alone wouldn't work on emulators due to the lack of a header, but that could be added later with the appropiate programs, or just implementing all the database stuff to the emulators that want to be compatible with this.

[Matthias_H]

The problem is bank switching. Not all memory segments are "visible" at a time, and without knowing the mapper chip used on the cart you can't access the entire ROM...

[ICEknight]

Oh, that makes sense... But how could a real NES see all the banks without knowing the mapper in advance, then?

[Matthias_H]

Oh, the NES is completely stupid with that regard. It's the code on the cartridge that takes care of the bank switching by making the NES read/write certain addresses and registers whenever needed. Even if the Retrode were capable of executing console code, this wouldn't give a coherent ROM image without knowing what these registers do.