The SID has U.S. Patent 4,677,890, which was filed on February 27, 1983, and issued on July 7, 1987. The patent expired on July 7, 2004.
Could this chip be made today? Does anyone outside of Commodore have the blueprints to make the SID chip or are the plans a secret hiding somewhere?
I suppose cost would be an issue today and someone might not break even. Are the plans available today?