I just came across this today, it looks like work that came about around January 2024 by Mattis Land. Mattis, not sure if you're active here, but this is really great work! The emulator code is here: https://github.com/MattisLind/DP2200/ An Unlisted demo of the emulator in action is here (running some CTOS software): https://www.youtube.com/watch?v=XfsMBhP13ww Might this CTOS be the only operating system fit on an audio cassette tape? -Steve