As we have probably known, Microsoft officially unveiled its next generation Xbox “game and entertainment system” two weeks ago. Given the Xbox 360’s all-new PowerPC-based embedded architecture, the question arises: What operating system is embedded inside the Xbox 360?

The earlier Xbox (shown on the right) is based on a Pentium-family processor and is rumored to run a variant of Windows 2000. But the Xbox 360 has a completely different architecture, based on a custom triple-core IBM PowerPC processor along with other specialty silicon including a custom graphics processor made by ATI, plus 512MB of system DRAM. So, since Windows hasn’t supported the PowerPC architecture since Windows NT 4.0 SP3, and Windows CE also doesn’t support PowerPC, below are some questions to ponder:-

• Has Microsoft ported Windows XP to the PowerPC for the Xbox 360? Or, Windows CE?
• Does the Xbox 360 run a version of some off-the-shelf embedded OS, perhaps a variant of BSD UNIX?
• Does the Xbox 360 run a completely new embedded software platform developed specifically for Xbox use?

Below is said by ExtremeTech technology analyst Jason Cross:-

Quoted:
The original Xbox ran an OS that had its roots in Windows 2000. The Xbox 360’s OS, in turn, has its roots in the OS of the original Xbox. I’ve been told (not by Microsoft, but by one of its hardware partners) that the Xbox absolutely positively does NOT run Linux or Unix or some variant of that. The Xbox 360 project started with the Xbox OS the same way the Xbox project started with Windows 2000. They cut, added, and changed it in both large and small ways. It’s now quite a bit different from the Xbox OS, which was itself quite a bit different from Windows 2000.

As suggected by him, the best way to think of it is as “The Xbox 360 OS“. But if you really have to think of it in Windows terms, you could say it has roots in Windows 2000 by way of the original Xbox, albeit with sweeping changes along the way.

As the conclusion, it’s believed that the Xbox 360 reportedly runs a second-order derivative of Windows 2000 that has been ported to the custom triple-core IBM PowerPC processor.

[Source]