After 25 years, the original Xbox's last hidden ROM has finally been dumped: the CPU's microcode!
This has been a goal of mine for over 6 years, and I've worked on it off and on ever since.
Over the last couple of weeks, while building inventory and shipping orders, I've also been running hardware tests 24/7. This poor Xbox has rebooted over 50,000 times in those two weeks alone.
And it finally paid off.
The dump covers the entire 4,096-line microcode address space. The ROM itself occupies 3,200 of those lines, roughly 12 KB of microcode.
I can't overstate how huge this feels. After all these years, I finally have it.
A full write-up is coming next year!