Diatonic scale are major scales (those with a major third/triad: Ionian, Lydian, and Mixolydian), three are minor (those with a minor third/triad: Dorian, Phrygian, and Aeolian). To these may be added the seventh diatonic scale, with a diminished fifth above the reference note, the Locrian scale. These could be transposed not only to include one flat in the signature (as described by Glarean), but to all twelve notes of the chromatic scale, resulting in a total of eighty-four diatonic scales. The modern musical keyboard originated as a diatonic keyboard with only white keys. The black keys were progressively added for several purposes:
Ditonic scale Ditonic scale A ditonic scale is a musical scale or mode with two notes per octave. This is in contrast to a heptatonic (seven-note) scale such as the major scale and minor scale, or a dodecatonic (chromatic 12-note ) scale, both common in modern Western music. Ethnomusicologist Bruno Nettl noted that ditonic scales were common in many parts of the world but often limited to specific music types, such as children's songs, with the exception of some tribal societies. The Cheremis (Mari people) of Russia employ ditonic scales in children's songs, generally with the two notes a minor third apart.