The Xbox gpu and apu <i>are</i> &#x27;off-the-shelf&#x27; in the sense that they were re-used in nvidia retail chips. But you&#x27;re right, that doesn&#x27;t mean much in terms of public documentation.<p>So you do some reverse-engineering. On the whole it isn&#x27;t much work than other consoles of that generation. The only reason there hasn&#x27;t been any activity is because nobody (outside of the Xbox backwards compatibility team) sat down and did the work (because there&#x27;s no incentive to)