are displacement-sensitive, i.e., when a key is partially pressed, the corresponding note (pipe, reed, etc.) in the organ produces a different, quieter sound than when the key is fully pressed. In some organs, the pitch or tone colour may also be altered. Small tabletop organs and accordions often respond similarly, with sound output increasing as keys are pressed further down. Even the small circular accompaniment ("one button chord") keys found on accordions and on some organs exhibit this phenomenon. Accordingly, some electrically actuated organs have retained this form of keyboard a 34-rank organ in the Swiss village of Ursy is equipped with hi-tech features from Syncordia, including what some erroneously claim is the first non-mechanical action that directly controls the opening of a pipe organ's pallets in direct proportion to key movement, ostensibly combining the virtues of electric action with the intimate control of tracker action. However, Vincent Willis' 1884 patent Floating Lever pneumatic action also had this capability. Other more sophisticated sensitivity forms are common in organ keyboards. Both the Pratt Reed and Kimber Allen 61-key (5-octave) keyboards have provision for up to nine rails so they can sense various amounts of displacement, as well as velocity in various regimes of distance from the top to the bottom of the key travel of each key. Some modern instruments, such as the Continuum, a MIDI controller for keyboards, have extremely sophisticated human interface schemes that provide dynamic control in three dimensions. In principle, displacement can be differentiated to get velocity, but the converse is not entirely practical, without some amount of baseline drift. Thus a displacement sensing keyboard may be better at providing both organ and piano feel in a single keyboard controller. Most digital pianos implement a displacement-sensitive keyboard, in order to simulate the sound-stopping length of the note after the key is released. On an acoustic piano, releasing a key after being partially depressed will result in a quieter, shorter sound stopping. The displacement-sensitive keyboard on a digital piano were designed to simulate the similar effect. Other types Acoustic pianos have expression pedals that change the response or tone of the instrument. On small upright pianos, the soft pedal (also called una corda or half-blow pedal) moves the hammers closer to the strings. On grand pianos, the soft pedal moves the hammers sideways so each hammer strikes only part of its string group. The sustain pedal (also called