MCPX
From xboxdevwiki
The MCPX is the southbridge chip of the Xbox chipset by Nvidia. It contains the sound processors (APU and ACI) and also the USB, PCI, IDE, etc, controllers[1], [2].
The MCPX is also the home to the secret MCPX ROM.
And it's also the home of the famous PC Speaker Signal.
One just has to solder a Speaker on (MXPC pin L21) and it can be used just like on the PC.
For some test code see https://github.com/0DaveX/beep/
