This paper documents some aspects of the design of zita-scope, an Audio Oscilloscope application for the GNU/Linux system. It is designed to permit accurate display and measurements on audio waveforms captured from any source via the Jack audio server. Topics covered include performance requirements, an analysis of some problems that need to be considered, and an overview of the implemention structure. The software will be available at the time this paper is presented at the 2013 Linux Audio Conference in Graz.