Related to the arcicembalo, the cimbalo cromatico was a type of harpsichord in use during the late 16th and early 17th c. While most keyboards were tuned in 12-note meantone temperament, limiting the number of available sharps (three) and flats (two), the cimbalo cromatico's 19-note keyboard contained separate keys for all sharps and flats. Though useful, the instrument lacked influence; composers tended to confine themselves to the meantone system, using the more widespread instruments with split keys for the extra notes needed.
"Music for the Cimbalo Cromatico and the Split-Keyed Instruments in Seventeenth-Century Italy,"
Performance Practice Review:
1, Article 8.
Available at: http://scholarship.claremont.edu/ppr/vol5/iss1/8