> On Nov 22, 2022, at 11:49 AM, Douglas Quagliana <dquagli...@gmail.com> wrote: > > Has anyone experimented with generating and detecting tones on the cassette > port other than the standard cassette mark and space frequencies?
Douglas, While this isn't a direct answer to your question, for which I apologize, it may be a useful lead to mention that the original heritage TRS-80 Models I / III used the cassette port as audio outputs for music and in some cases speech. I believe the circuit and method of operation was similar -- your approach seems reasonable.
