[DeckerEgo] took a bit of inspiration from an even simpler macro pad we featured before which is based around the idea that a shockingly high number of songs use the same four chords. His macro ...

Using MIDI over USB, it plays the I-V-vi-IV progression in any key. It plays in chord mode, arpeggiated mode, or mixed mode at any sensible tempo. You can check out a video of the 4chord playing ...

The chord progressions used in the vast majority of pop songs are pretty straightforward, consisting of a cycle of between two and four chords ... major chords, and lowercase for minor and diminis ...