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[jedimike]

http://blogs.msdn.com/xboxteam/archive/2006/02/17/534421.aspx

The Xbox Operating System
Sorry it's been a while since my last post - blogging is hard to keep up with, especially when it's not your job. I'm off to Japan next week, so it will probably be another week of silence before you hear from me again.

One of the first questions I get when someone hears I work on Xbox is "So, what operating system do you guys use? Windows 2000, right?" I am honestly not sure where the Win2K misperception comes from, but Xbox runs a custom operating system built from the ground up. While our operating system exports many of the same APIs found in Win32 (e.g. CreateThread or WaitForSingleObject), not everything is there. For instance, there is no use for CreateWindow on Xbox - all graphics are done through (our own flavor of) Direct3D.

There are a number of reasons both Xbox and 360 have their own OS. First, it gives Xbox a chance to own its own destiny in terms of architecture. When you have your own operating system, it's easy to go in and change things. Second comes performance. There isn't much of a hardware abstraction layer on Xbox - most stuff talks almost directly to hardware. This eliminates a lot of software overhead you might find on a PC. Third is security. With our own operating system, it also becomes a lot easier to design & implement our own security architecture. As the community is finding out, there is a lot of custom stuff.

The operating system is more than just the kernel. On Windows, you have critical components such as explorer.exe, shlwapi.dll, user32.dll, and others that are required for your system to function. On Xbox 360, we have similarly critical components. When you see a required system update from Xbox Live, we are mostly updating these critical components with fixes as well as new features.

That's a primer on our operating system. I wouldn't want to spill all my guts in one post 'cuz then I'd have nothing to talk about later on. Let us know if you want to know more about the OS in the comments...

 

[jooey]

One of the first questions I get when someone hears I work on Xbox is "So, what operating system do you guys use? Windows 2000, right?"

if I were him I'd become a violent person very quickly.

 

[sky]

In Opening the Xbox, it describes Jon Thomason and Allard choosing WinNT/2k as the starting point for the Xbox OS, after a somewhat false start with WinCE. So while it sounds like that may have indeed been where they started, in the end it was shrunken down so much, and then built on top of, it definately turned in to it's own beast.

 

[Tenacious-V]

In Opening the Xbox, it describes Jon Thomason and Allard choosing WinNT/2k as the starting point for the Xbox OS, after a somewhat false start with WinCE. So while it sounds like that may have indeed been where they started, in the end it was shrunken down so much, and then built on top of, it definately turned in to it's own beast.

And what a perfectly exploited beast it became!

My replacement xbox is more a PC than my PC is sometimes.....

 

[kaching]

So they wanted all the other console manufacturers to use WinCE in their machines but ultimately weren't willing to use it themselves. Eenteresting.

 

[aaaaa0]

So they wanted all the other console manufacturers to use WinCE in their machines but ultimately weren't willing to use it themselves. Eenteresting.

A few good reasons (from what I remember):

1. WinCE only supported 32 MB per process. Xbox had 64MB of RAM.
2. WinCE didn't have good x86 support, it was targetted towards SH4, ARM, and MIPS.
3. WinCE didn't support hard disks very well.

None of these limitations are a problem for Dreamcast. (Or PS2 for that matter )

 

[Lord Error]

A few good reasons (from what I remember):

1. WinCE only supported 32 MB per process. Xbox had 64MB of RAM.
2. WinCE didn't have good x86 support, it was targetted towards SH4, ARM, and MIPS.
3. WinCE didn't support hard disks very well.

None of these limitations are a problem for Dreamcast. (Or PS2 for that matter )

You forgot the main limitation - back then (1999-2000), WinCE was just crap and inefficient I think anyone who used pre-Pocket PC WinCE device around that time, or played a WinCE Dreamcast game can attest to that.

 

[kaching]

A few good reasons (from what I remember):

Not necessarily compelling on their own, since it just begs the question, why not just upgrade WinCE to include those capabilities? Ultimately, I think they made the right decision, probably realizing that the main reason not to use WinCE had less to do with its limitations and more to do with the fact that as a generic OS it was a poor fit for hardware that has a closed, proprietary architecture out of which you're looking to maximize performance as much as possible. I wonder if they had realized that sooner, that a coded to fit solution would have been more preferable to console manufacurers, whether they would have had a better chance with Sony in the first place. Like I said, interesting, as a "what if" scenario.

 

[sky]

Not necessarily compelling on their own, since it just begs the question, why not just upgrade WinCE to include those capabilities?

Yeah... they did consider it, but the task (making WinCE DirectX8 compatible) turned out to be pretty huge, and messy. Also the limitations mentioned were an issue... it just wouldn't give them the gaming performance necessary. There's a funny scene recounted, where Gates demands "tell me which dreamcast games used WinCE!" to gauge it's success, and all the execs are basically "uhh... uhmm......" "........"