Intel & AMD have a cross-license agreement covering everything x86 (and x86_64) thanks to lots and lots of lawsuits over their many years of competition.

So while Intel had to bow to AMD's success and give up Itanium, they weren't then limited by that and could proceed to iterate on top of it.

Meanwhile it'll be a cold day in hell before Nvidia licenses anything about CUDA to AMD, much less allows AMD to iterate on top of it.

The original cross licensing was government imposed because a second source was needed for the military.

Makes you wonder why DoE labs and similar facilities don't mandate open licensing of CUDA.

Isn't API out of scope for copyright? In the case of CUDA, it seems they can copy most of it and then iterate in their own, keeping a compatible subset.

In hindsight, yes, but just because a specific technology is leading an industry doesn’t mean it’s going to be the best option. It has to play out long enough for the market to indicate a preference. In this case, for better or worse, it looks like CUDA’s the preference.

> It has to play out long enough for the market to indicate a preference

By what measures hasn't that happened already? CUDA been around and constantly improving for more than 15 years, and there is no competitors in sight so far. It's basically the de facto standard in many ecosystems.

There haven’t been any as successful, but there have been competitors. OpenCL, DirectX come to mind.

SYCL is the latest attempt that I'm aware of. It's still pretty active and may just work as it doesn't rely on video card manufactures to work out.

SYCL is the quasi-successor to OpenCL, built on the same flavor of SPIR-V. Various efforts are trying to run it on top of Vulkan Compute (which tends to be broadly support by modern GPU's) but it's non-trivial because the technologies are independently developed and there are some incompatibilities.