I just realized that I have not given an update on the Cassette Tape Interface board. The boards have been received and I have populated one, got the software going and started testing. There is always more testing (a.k.a., playing) to do but writing to the tape, reading back all seem to be working OK so I have put up the build files on the documentation page. A more few of the project details are on hackaday and the documentation is mostly current but I am sure that I have overlooked something. I have pasted several waveforms from the scope and logic probe into the user’s manual and, hopefully, reasonable enough descriptions to figure everything out. Also, since this is based entirely on Intel’s design shown in MCS-80 and MCS-85 documentation so you can look there if you need more information.
One hopefully useful piece of work is the cassette tape interface example code in the Utilities program download. There you will find three key *.a85 files for the utilities and examples of how to use them. I am continuing to fill out more example code as I have time to get back to that project. At this point, there are utilities for subroutines to write a tape leader, read from, and write to tape as well as example code to do all three. I also plan on doing a supporting video someday.
Hopefully, these will all improve as people start playing with the cassette board and provide feedback as to what additional information is needed.