This article starts from the assumption that musicology needs methods borrowed from philology for studying computer music. The analysis of the creative and revising process that John Chowning carried out in the realization of Stria (1977) is made possible by textual criticism and interpretation based on digital and audio sources, sketches and oral communications. This research moves from the hypothesis that Stria exists in several versions and follows the historical genesis of the assembling of the sections. Conclusions trace the various stages of the assembling process, from the very first synthesis of the piece, to two different and coexistent 4-channel and stereophonic versions.