Development of the keyboard
Evolution from early forms
Long before the appearance of the first stringed keyboard instruments in the 14th century, the keyboard was developed and applied to the organ. A keyboard of the kind familiar today—a series of parallel levers hinged or pivoted so that they can be pushed down by the fingers—first appeared on the hydraulus, an organ probably invented in Alexandria in the late 3rd century bc. This type of keyboard seems to have disappeared after the fall of the Roman Empire, and the organs of the early Middle Ages generally had sliders that were pulled out to sound different notes; some may have had keys that turned like the key for a lock. Keys of the last type were certainly used on the organistrum, a large medieval hurdy-gurdy operated by two players: one turned a crank rotating a wheel that rubbed against one or more strings to make them sound, while the other produced different notes by turning the key-shaped levers that stopped the strings at various points (much as guitar strings are stopped against the fingerboard).
Some small portable organs had push buttons instead of keys as late as the 1440s, but a keyboard resembling the modern type existed in the 14th century, although the arrangement of naturals and sharps (corresponding to the white and black keys on the modern piano) was only gradually standardized. The arrangement of the keys depended in part on the music played and partly on the current state of musical theory. Thus, early keyboards are reported with only a single raised key in each octave (B♭), and there were organs that had both B and B♭ as “natural” keys, with C♯, D♯, F♯, and G♯ as raised keys. The colours of the keys—white for naturals and black for sharps—became standardized much later, about 1800, depending on fashion or on the relative cost of such materials as bone, ivory, or boxwood for the “white” keys and stained hardwood or ebony for the “black” keys. Flemish instruments had bone naturals and oak sharps by 1580; French and German instruments had ebony or fruitwood naturals and bone or ivory sharps until the 1790s.