These are hardware exploits. They allow an Xbox 360 to run unsigned code.
A massive library of tutorials existed for C# and XNA. Failing Bird [Indie] [Jtag/RGH]
Failing Bird is an intriguing footnote in the history of the Xbox 360 indie scene, specifically within the homebrew community of JTAG/RGH-modified consoles. What is Failing Bird? These are hardware exploits