XBOX360: Backwards compatibility may only be limited

[jvd]

But you can't just run the games on the new hardware. I'm sure if you just passed say, Halo's T&L calcs to the ATI chip it would crash, as the 2 chips don't work the same way. I mean, nvidia's drivers won't work on ATI's cards, why would XB1 stuff work on XB360 stuff?

the calls should have been handled through the dx type api which to my understanding is very close to the normal dx api . So i don't see what would be so hard ? The api would just treat the r500 as if it was the nv2a . At least for any game that doesn't go past the api lvl .

 

[Reznor007]

But you can't just run the games on the new hardware. I'm sure if you just passed say, Halo's T&L calcs to the ATI chip it would crash, as the 2 chips don't work the same way. I mean, nvidia's drivers won't work on ATI's cards, why would XB1 stuff work on XB360 stuff?

the calls should have been handled through the dx type api which to my understanding is very close to the normal dx api . So i don't see what would be so hard ? The api would just treat the r500 as if it was the nv2a . At least for any game that doesn't go past the api lvl .

There's a problem with that though. There is no API on the Xbox. The SDK does have a DX like API, but the dll's are statically linked to the game executable, meaning each game has it's own version of DX glued to it. Because of that, there are no API calls to the Xbox hardware, only direct machine code for the various chips, which are very far from instruction compatible with a new architecture.

 

[Geeforcer]

Which brings up the question: How is Sony going to do it in PS3?

 

[Sdw]

Could it be that they won't be using emulation at all, but instead recompiling the source code for the 360 (with appropriate changes made) for each "popular" game, release this new .exe via Live and just use the data from the original game? I don't know if that would be feasable though...

 

[ndoogoo]

But you can't just run the games on the new hardware. I'm sure if you just passed say, Halo's T&L calcs to the ATI chip it would crash, as the 2 chips don't work the same way. I mean, nvidia's drivers won't work on ATI's cards, why would XB1 stuff work on XB360 stuff?

the calls should have been handled through the dx type api which to my understanding is very close to the normal dx api . So i don't see what would be so hard ? The api would just treat the r500 as if it was the nv2a . At least for any game that doesn't go past the api lvl .

There's a problem with that though. There is no API on the Xbox. The SDK does have a DX like API, but the dll's are statically linked to the game executable, meaning each game has it's own version of DX glued to it. Because of that, there are no API calls to the Xbox hardware, only direct machine code for the various chips, which are very far from instruction compatible with a new architecture.

The emulator could have a database all the different versions of DX code signatures. This will find all the DX related call addesses in the game you are emulating and redirected them to the real DX API.

Use X-box DX code signatures to find all relevant DX calls/addresses and hook them to the real X-box2 DX API.

 

[Joe DeFuria]

Now thats what I like to hear! I bet you money each game will likely need a "profile" of sorts to be stored on the hard drive in order to work right, and users will be able to download more profiles as time goes on over XBOX Live. As long as MS plans to keep up work to make most games BC eventually through Live updates, I'll buy the console.

I'd wager there would be two different means of updating "profiles."

1) Live (of course)
2) "Compatibility CD/DVDs". (Contains the same data you'd download from live). One DVD covers many, many games. Sell these for some nominal cost like $5 or even give them away in game stores "when you buy any other xbox or xbox2 game".

 

[Reznor007]

But you can't just run the games on the new hardware. I'm sure if you just passed say, Halo's T&L calcs to the ATI chip it would crash, as the 2 chips don't work the same way. I mean, nvidia's drivers won't work on ATI's cards, why would XB1 stuff work on XB360 stuff?

the calls should have been handled through the dx type api which to my understanding is very close to the normal dx api . So i don't see what would be so hard ? The api would just treat the r500 as if it was the nv2a . At least for any game that doesn't go past the api lvl .

There's a problem with that though. There is no API on the Xbox. The SDK does have a DX like API, but the dll's are statically linked to the game executable, meaning each game has it's own version of DX glued to it. Because of that, there are no API calls to the Xbox hardware, only direct machine code for the various chips, which are very far from instruction compatible with a new architecture.

The emulator could have a database all the different versions of DX code signatures. This will find all the DX related call addesses in the game you are emulating and redirected them to the real DX API.

Use X-box DX code signatures to find all relevant DX calls/addresses and hook them to the real X-box2 DX API.

There's an Xbox emulator for PC that uses that idea. Last time I heard it was able to boot Turok Evolution and that's it.

Also, I don't know how that would work if a game was made that did not use DX and just did direct assembly programming.

 

[AlNom]

Can we expect HD resolution? That would just be like changing resolution on a PC right? Forced AA?