A musical interval of less than a half step. (The half step is the interval between any two adjacent notes in the conventional equal-tempered scale.) Some synths which have panel controls allowing the keyboard scaling to be adjusted can be made to play microtones by reducing the scaling. The main disadvantage of doing this is that key fingering has to be re-learned since the conventional notes of the equal tempered scale are no longer on their customary keys. Another disadvantage, when MIDI is involved, is that MIDI note on messages only allow for 128 possible notes, so, for example, if scaling is set for 24 notes per octave (so-called "quarter steps"), then only a span of 5 and a fraction octaves can be played. An alternate keyboard may provide a better key arrangement for play microtonal scales, as well as a workaround for the MIDI note span limitation.