Pragmatics of a polyphonic calculator (chapter 2)

[BarryMead]

I can think of one other requirement that seems important for a polyphonic device.

The KEYBOARD LOGIC should allow for multiple simultaneous keys to be pressed at once if you intend to support chords. Typical row/column decoders do not allow for this so you may have to have one CPU I/O pin for each key if you want no limitations on key press combinations.

Hope this helps, Barry