SPARC has been "open" for several decades at this point. All of the ISA specifications are freely available[1] and you can buy a license to manufacture SPARC h

SPARC has been "open" for several decades at this point. All of the ISA specifications are freely available[1] and you can buy a license to manufacture SPARC hardware for $99. [1] https://sparc.org/technical-documents/ https://sparc.org/technical-documents/