The Janko keyboard is a musical keyboard layout for a piano designed by Paul von Janko in 1882.
Based on the premise that the hand can barely stretch more than a 9th on the piano, and that all scales are fingered differently, Janko’s new keyboard had two interlocking ‘manuals’ with three touch-points for each key lever. Instead of the traditional row of white and black keys, the keyboard has an array of keys.