Technical Implications of Backwards Compatibility for CPU and GPU? *spawn*

[BRiT]

@sebbbi

Yes, but its not like the games are having direct access to hardware registers and instructions; it still goes through a driver level or abstraction layer that would be able to be emulated or shimmed/bridged on future hardware, right? In future hardware the GCN shader instrinsics would need to be replaced with the new equivalents if the new hardware doesn't have it. Would that still be doable, a sort of driver specific hack for the games with shader substitutions?

The raw hardware level as in registers and peeks and pokes and special commands is what I think of as low level access, like back in the Atari/Commodore days or the days of DOS with Soundblaster or MIDI IO Ports. In that regards, then perhaps there is no such thing as low level access anymore, unless the games are able to use precompiled shadees and submit them direct to the GPU?

 

[Pixel]

I recall reading Microsoft has a team of ~200 (which they specifically mention include an unspecified number of software engineers) who are working to ensure compatibility on titles on XOX. I'm guessing part of their roll was to also work on the emulation of X360 and OGXbox games but it shows that a lower level API makes compatibility harder between even a very similar cpu architecture (jaguar vs jaguar with tlb caches modified and moderate mmu modifications) and somewhat similar gpu architectures which still has some Southern Island architecture elements remaining (iirc according to the Scorpio Engine Presentation at HOTCHIPS) derived from the the OG XBOX One/S, and an identical southbridge (not sure if that matters).