In re Mahony, 421 F.2d 742, 164 U.S.P.Q. (BNA) 572 (C.C.P.A. 1970) (full-text).
Factual Background Edit
Mahony was the first case to consider claims to a process beginning and ending within a digital computer. The applicant claimed a new method of identifying framing bits in a "receiver of digital information, such as a digital computer" and disclosed digital circuitry in block diagram form as well as an algorithm.
C.C.P.A. Proceedings Edit
The "mental steps" doctrine constituted the basis of the Patent Office's rejections; and the examiner demonstrated to the court that the algorithm could be practiced by pencil and paper. The court declined to address the "mental steps" issue and reaffirmed its intention to confine the relevance of mental practice to Section 112 scrutiny.
The claims were sustained when the court found the recital of "bits" and "bit stream" sufficient to limit the claims to machine practice. The examiner was found to be operating not on a bit stream but on a "character representation" of a bit stream when following the algorithm by hand.