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:
Hungarian minor scale indicates a half step, and + indicates an augmented second (the latter of which is enharmonically equivalent to a minor third but is notionally distinct). The scale contains two augmented seconds, one in each tetrachord. It also contains an augmented fourth (which is enharmonically identical to a tritone) between the first and fourth degree. Intriguingly, this scale (and its modes like the double harmonic scale) is the only seven-note subset of the equally tempered chromatic scale that is "perfectly balanced"; this means that when its pitches are represented as points in a circle (whose full circumference represents an octave), their