<P> Some 1960s electronic organs used reverse colors or gray sharps or naturals to indicate the lower part (s) of a split keyboard: one divided into two parts, each of which produces a different registration or sound . Such keyboards allow melody and contrasting accompaniment to be played without the expense of a second manual and were a regular feature in Spanish and some English organs of the renaissance and baroque . The break was between middle C and C - sharp, or outside of Iberia between B and C. Broken keyboards reappeared in 1842 with the harmonium, the split occurring at E4 / F4 . </P> <P> The reverse - colored keys on Hammond organs such as the B3, C3 and A100 are latch - style radio buttons for selecting pre-set sounds . </P> <P> The chromatic compass of keyboard instruments has tended to increase . Harpsichords often extended over five octaves (61 + keys) in the 18th century, while most pianos manufactured since about 1870 have 88 keys . Some modern pianos have even more notes (a Bösendorfer 225 has 92 and a Bösendorfer 290 "Imperial" has 97 keys). While modern synthesizer keyboards commonly have either 61, 76 or 88 keys, small MIDI controllers are available with 25 notes . (Digital systems allow shifting octaves, pitch, and "splitting" ranges dynamically, reducing the need for dedicated keys .) Organs normally have 61 keys per manual, though some spinet models have 44 or 49 . An organ pedalboard is a keyboard with long pedals that are played by the organist's feet . Pedalboards vary in size from 12 to 32 notes . </P> <P> In a typical keyboard layout, black note keys have uniform width, and white note keys have uniform width and uniform spacing at the front of the keyboard . In the larger gaps between the black keys, the width of the natural notes C, D and E differ slightly from the width of keys F, G, A and B . This allows close to uniform spacing of 12 keys per octave while maintaining uniformity of seven "natural" keys per octave . </P>

The black key to the right of g is called