Historians of computing know of Calvin Mooers (1919–1994) for several contributions to electronic computing and programming languages. This paper describes a less well-known development by Mooers. Around 1950, he devised a coding scheme for edge-notched cards—a decidedly "low-tech," nonelectronic method of information storage and retrieval, based on cards with notches cut into their edges. In spite of his experience and training in electronics, Mooers believed that existing digital computer projects were ill-suited for the storage and retrieval of large amounts of information. Edge-notched and other cards had been in common use for data retrieval, but none were able to handle the explosion of information occurring in the sciences after World War II. "Zatocoding" was to address the deficiencies of both existing electronic computers and of other card systems, as it was based on a more theoretical understanding of the nature of information and its retrieval. Zatocoding did not prevail, but I argue that the theoretical work done by Mooers proved later to be of fundamental importance to modern databases, encryption, and information retrieval.