Flarestorm, the oh-so-very-nearly-finished PSX emulator has gone open source, with SDK and sources available at the given link. If anyone proficient in Japanese would care to translate when this actually happened, you're free to do so
Now, to build the thing - the source is 6 months newer than the binary last available...
Now, to build the thing - the source is 6 months newer than the binary last available...