I found http://openbookproject.net/py4fun/ http://openbookproject.net/py4fun/ a while back. It has quite a few projects, one of which is a "toy computer" emulat

I found http://openbookproject.net/py4fun/ http://openbookproject.net/py4fun/ a while back. It has quite a few projects, one of which is a "toy computer" emulator written in Python. It goes from the raw emulator, through to writing a simple language and compiler for it. It is a toy example (hence the name, I guess), but a picture is worth a thousand words, if you're wondering about the nitty gritty of it all.