The Ninth Circuit Court of Appeals has held that all computer programs are copyrightable regardless of their function.
Apple Computer, Inc. v. Formula Int'l, Inc., 725 F.2d 521 (9th Cir. 1984) (order affirming preliminary injunction).
Richard F. Paciaroni,
Copyright Law - Computer Programs,
Duq. L. Rev.
Available at: https://dsc.duq.edu/dlr/vol23/iss2/11