It's seems to me Xbox 360's R500 VPU could be SM4.0...

Discussion in 'Console Technology' started by scificube, May 13, 2005.

  1. scificube

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    Ok, I got blasted for mentioning this idea in the thread speaking about the Xbox 360 leaked specs on pg. 11 or 12 I think.

    I just not gonna let it go :lol:. Call me crazy but I feel the R500 may in fact be a SM4.0 part instead of SM3.0++ as has been the predominant assumption to date. I'm not saying it's an official SM4.0 part but it could be for all intents and purposes.

    I'm thinking that just like the Xbox used a custom OS and directx version the Xbox 360 can as well but in this case directx is actually WGF2.0 or the part of it that handles 3D rendering directly.

    I got blasted for thinking WGF2.0 was complete or even a version of Longhorn etc was. This is understandable, but I'm not really saying all that. What I'm saying is that they could use a beta version of or the Kernel that's going to end up in Longhorn and some beta/custom WGF2.0 'like' interface (where like could be beta or stop gap...pick what suits you...or don't). The Kernel would be the first thing anyone would get done in implementing an OS. It's not to hard for me to think Longhorn's is good to go beyond some tweaking with system level apps not yet complete but also not needed for the Xbox 360. WGF may not be complete in removing all the overhead in directx as it is now or having all parts of spec finalized but it's not so hard to think they got enough to code up a custom version ONLY for the Xbox 360's R500 VPU.(where any reduced overhead is still better than directx as it is now) I'd actually think getting WGF going would be an utter priority at MS given how Longhorn biggest draw is supposed to be a 3D desktop.

    ATI also has been working on this VPU for how long? ...a long time. The R500 architecture has always been thought of as destined for SM4.0 compliance but limited to SM3.0++ in the Xbox 360. Well...why couldn't MS and ATI remove the limits if they already had stuff ready to go beyond the very same? Well maybe not ready to go "big time" but there in substance.

    To me it seems like a great opportunity to experiment for both parties. ATI gets a spin with SM4.0 so that they can better tweak the R600 iteration and not only that whisper in MS's ear about things that gave them difficulty or they'd like to see in the final spec which would arrive later on PC. MS gets to see just which parts of the spec need revision, more emphasis, removal or inclusion. With performance data it be a great way of finding the bottleneck in their implementation and further eliminating the API's overhead. MS also gets two other advantages. It's get the jump on the OpenGL consortium which must answer WGF2.0's SM4.0 and all the other competition in console arena as they would surely be restricted to SM3.0++ (thus no load balancing on the GPU/VPU) unless they elected to craft an comparable API themselves (probability 0.0001 % but I'm just guessing it's hard to do this).

    The latter is actually pretty significant with respect to the concept of "load balancing" on the VPU that I'm sure many here more capable than I are well aware of. This could be the reason why EA and others have recently commented to the affect the the Xbox 360 was more powerful than they expected (not to discount the GFLOP bump in the CPU of course).

    Enough yammering I've made my case and if I'm wrong then I'm wrong but apart from my observations about the use of unified shaders found in the leaked specs and now the official specs here is an interesting comment that lends further credence to the idea that I am not completely insane :twisted:



    http://features.teamxbox.com/xbox/1145/The-Xbox-360-Dissected/p3/

    I note this unified shader language and the mention of WGF2.0. This language would be the successor to HLSL and would compile up to what shader profile with WGF2.0...

    I got excited here's another quote to this affect.

    What say you? (Be gentle...)
     
  2. blakjedi

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    Cant say whether your assumption is true but I have argued the same thing before...

    on a similar note does work on x360 give ATI a leg up on the specification over nvidia in the future? i would think that ATI is now privy to all sorts of things that nvidia would see until its too late. ATI may move a generation ahead on their parts in the future... hey but im a security analyst not a programmer so...
     
  3. scificube

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    Beyond what I mentioned I don't think so. MS WILL listen to Nvidia in "finalizing" the specs so Nvidia won't get screwed into having to make ATI like parts.

    They just don't get the advantage of playing ahead of the game so to speak.

    IIRC Nvidia is going to implement unified shaders at the software level anyway so the time it takes them to recover ground (as much as possible at least) may be relatively fast if they have some good coders on the task. I'm sure they're already working how to do it at present regardless.
     
  4. ShootMyMonkey

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    If it IS SM4.0, wouldn't we have heard something about WGF 2.0? As if to at least suggest that more parts of the WGF2.0 spec are pinned down or that ATI is putting out a WGF2-compliant part?

    The scope of SM4.0 has been going up and down and back and forth for damn near forever. I think it'd be newsworthy to see something finalized.
     
  5. Titanio

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    Unless MS has cut the SM4.0 spec to meet X360's shader functionality, the chances of this are very slim imo.

    I also don't know about working on x360 necessarily helps ATi get a leg up over NVidia. NVidia's next-gen part after the Xbox class of hardware was the NV30 and we all know how that turned out..

    That said, they will have more experience with hardware unified shaders. But Nvidia isn't too keen on them at the moment anyway..
     
  6. Acert93

    Acert93 Artist formerly known as Acert93
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    But are those not two separate issues? Yes, NV worked with MS on the Xbox, but they also seemed to resist MS on DX9 specs. And the rumblings are that NV is resisting certain things on the DX10 spec also.

    I think NV, as really the trend setter in the 3D market (look at their game partners and the influence they have on games... they have a heft install base no doubt), would like to use that influence to go in the way that best meets their philosophies. Obviously any company would want to do as much, but their resistance to MS seemed to hurt them with DX9. (That is what I heard at least).

    Obviously there is some serious disagreement about featureset for DX10/WGF 2.0, it will be interesting to see what nVidia does. One thing is for sure: MS probably is not too happy with them still over the Xbox GPU. That seems to be one of the biggest factors to the early launch and the stop in Xbox production come this summer. That is a burned bridge, so it is in MS interest to make sure ATi remains competitive over the next 5 years so they can make their next GPU.
     
  7. scificube

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    Would it make more sense if what the Xbox 360 was using was MS and ATI's view of what the WGF2.0 spec should be and that in 2006 the spec used in Longhorn would be more inclusive of Nvidia out of necessity?

    I would like to read about the disagreements between the parties if it's public knowledge somewhere.
     
  8. Guden Oden

    Guden Oden Senior Member
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    It'll have SM4 in your dreams pal...
     
  9. scificube

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    It already does :wink: I'm curious as to whether it does in reality or just how close it can get :wink:
     
  10. jvd

    jvd
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    aye , sm4 seems to be at least 2 years away . But it can very well have something beyond sm 3.0

    I'm more interested in the compression they are talking about
     
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