In re Mahoney, 421 F.2d 742 (C.C.P.A. 1970) (full-text).
The invention involved a data communication system, in which circuits and methods synchronized a receiver of digital information. The patent application disclosed a method of synchronizing a receiver with a bit stream containing digital information. The claims were directed to steps involving "comparing," "registering," and "counting." These functions were performed on "bits" and "bit streams."
The PTO rejected these claims under 35 U.S.C. §112, stating that the claims failed to particularly point out and distinctly claim the invention since they read simultaneously on statutory subject matter (machine implementation) as well as on nonstatutory subject matter.
The C.C.P.A. disagreed with this application of Section 112, and pointed out that both Sections 112 and 101 rejections would be overcome if the claims in fact covered only machine implementation. The court found that references in the claims to "bits" and "bit streams" were sufficient to preclude reading the claims on a mentally performable process. It was clear from this case that the method claims must include machine limitations to meet the requirements of Sections 112 and 101.