Revisited: JTAG 'Hacking' of the Original Xbox After 20 Years

This blog post details the author's successful attempt to 'hack' the original Xbox using its Intel Pentium III CPU's JTAG interface. The original Xbox's security relied on a 512-byte secret bootrom hidden within the NVIDIA MCPX Southbridge. While early researchers considered using the CPU's JTAG capabilities, it was deemed impractical due to the TRST# pin being grounded. The author designed a custom CPU interposer PCB to circumvent this, and using a vintage CodeTAP debugger, successfully dumped the secret bootrom via JTAG, proving a 20-year-old theory. This work is historically significant and provides valuable experience and resources for x86 JTAG research.