[WaxProlix]

Sort of ignorant and at least a little tangential here, but the notion of 'licensing' an instruction set seems a lot like licensing an API (cf the Java API copyright controversy) - are there parallels/precedents here or is it an unrelated issue?

[kragen]

The Federal Circuit's idiocy in the Oracle case aside, it's well established that copyrights don't cover methods of operation such as APIs or instruction sets. It's also well established that patents do, and that's what ARM licenses. Also they bundle mask works and copyrightable HDL code.

[WaxProlix]

Cool, thanks for responding - what is it about an ISA that makes it patentable where an interface might not be?

[kragen]

Interfaces are also patentable.