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darkknightkryta on 11 January 2012
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zarx said:
darkknightkryta said:

Direct X 9 series of cards can't use stuff from Direct X 10/11.  Shader programs written in Direct X 10 fully won't work in 9 (Unless you wrote them in 9 in the first place like Crysis).  And you're right, the unified shader architecture vs dedicated pipeline was the real problem with the PS3.  Hell the PS3 at launch was actually closer to a PC than the 360 was, but between the pipeline issue, OS footprint, dedicated ram vs unified, those were the real issues.  A good example of unified shaders vs dedicated would be Tomb Raider Legends.  The "next gen" features in the game would bring the game to a crawl no matter what video card was used.  Even the Geforce 9 series of cards had problems.  And why?  Cause Crystal Dynamics just threw the 360 game on a DVD and hope it worked, which is what was happening with early PS3 games.

I was talking about a presumably DX11 compliant unified shader GPU emulating an older DX9 compliant GPU, nothing to do with running DX11 code on a DX9 card or getting a DX9 engine to use DX10/11 effects. Ether of those things is obviously not possible (without rewriting the game), we were talking about maintainging backwards compatability and whether moving to a newer GPU architecture would cause problems for the PS4. I can't say I know much about the subject, but I know that DX9 engines can run on DX10 or higher cards without a problem so assumably MS managed to maintain backwards compatability when moving to DX10 and later DX11 architectures. Not that that means that Sony will be abale to do the same thing exactly as console games are often written to take advantage of quirks of the hardware meaning they will do strange and complex things that the hardware was not perhaps invisioned doing which could cause problems with compatability beyond keeping an API compatible that is why a straight hardware level legacy mode is preferable. But that is not really feasible as no one makes GPU architectures like the RSX anymore, without resorting to keeping an RSX arround for backwards compatability like the first PS3s did anyway, so a higher level solution will need to be found.

Ah, thought you meant something else.  I'm not 100% sure as I don't work for either graphic card vendors, but I'm sure it won't be a problem.  The bottom line for compatability is the assembly.  As long as they don't remove and as long as they keep the performance of legacy assembly ops, backwards compatability won't be an issue.  It hasn't even been much of an issue since Nvidia and ATI took over the market.