In order to really understand how this works, there is some required reading. First and foremost, get your feet wet with this gentle Forth introduction. After that, you should read how forth words are compiled into x86 code. Finally, you will need to reference the Adobe ActionScript Virtual Machine Spec to see the .abc file format and the corresponding bytecode. It also helps if you download tamarin and specifically, the tracing version. After you've spent a good week reading that, come back :).