Maaaan, this puts my Chordinator to shame... I thought my eventing was a simple approach to doing something a bit advanced, but this... this just blows it away, it seems.
I am a bit sad and envious now. I hope someday I am inspired to make something amazing, whether it be in Blockland or in real life, that can compare to this.
Excellent work, Icy.
[EDIT] Well, I found a bug in your CPU. The brick named "erasemem22" has an "onRelay->[some named brick]->setColor red" event on it. This seems to cause the 22nd note in the chain to not be erased correctly.
Also, a lot of the unsustained black key notes seem to just cut off abruptly whereas most of the others fade out really quickly, but at least they fade out. Just thought I would let you know.