128 * 4 * 4 * 2 = 4096 bytes
This array is meant to send midi data to a drum machine. Maybe I was seeing too big
when deciding to work with that much data. 64 bytes should be enough...
As you have not picked up the hint an Uno as 2K of ram for ALL its needs, your array trys to use all of that, even the you could build the program it could not run.
Mark