Use this on a headerless rom. Its size should be 1.572.864 bytes.
If you try opening a different rom in the editor, all sorts of weird things may happen, as it does not do any kind of verification.
I'm not responsible for any kind of side effects using this editor may cause. Use it at your own risk. Well, it's quite unlikely that using this will make your computer explode or anything... it may corrupt your room, so make sure you have a backup copy of it.

Not much else to read here...
If you'd like to contact me, drop me an e-mail: jagmotta@gmail.com