generalized keyboard is, in principle, a mapping of pitches onto a closed space in which intervals and chords have fixed shapes under transposition across the keyboard; thus a generalized keyboard is a useful tool for the analysis of harmonic structures. Implementations Bosanquet's 1873 harmonium has rectangular keys more or less horizontal and aligned vertically with 12 lines in each octave. The width of octaves is slightly compressed from usual, and the keys are narrow and undercut at the front. Arthur von Oettingen's 1914 Omnitonophonium harmonium has keys similar to Bosanquet's, but which aren't undercut (like Jankó's 1883 patent for his 12-tone keyboard). Arthur Fickénscher patented a keyboard in 1941 with rectangular keys overlapping in 12 staggered diagonal rows each representing the same named tones. Larry Hanson devised keyboards in 1942 with rectangular, as well as staggered "7"-shaped keys. Adriaan Fokker's 1951 31-tone organ used relatively short rectangular keys with sides relieved toward their fronts to form T-shaped playing surfaces, as well as longer rectangular keys in a concave arrangement for a pedalboard. Erv Wilson patented a keyboard in 1967 with five perpendicular chromatic lines of keys in an octave, using fourths as generators. Robert Moog built a prototype with undercut round front rectangular keys. Herman van der Horst built the first of four staggered square key Archiphones in 1970 for Anton de Beer. George Secor's 1974 generalized keyboards for the Motorola Scalatron used oval keys skewed in diagonal rows. Scott Hackleman and Erv Wilson designed a 19-tone generalized keyboard clavichord with oblong hexagonal keys in 1975, and marketed it as a kit. Michel Geiss, :fr:Christian Braut and Philippe Monsire built the Semantic Daniélou, a 36-tone (out of 53 just intonation notes listed in the book "Sémantique Musicale" by Alain Daniélou) electronic instrument, on behalf of the author, using staggered square key button keyboards from two Cavagnolo Midy 20 master keyboards, where each parallel row of keys offers a transposition by one comma. Harold Fortuin's 1994 Clavette midi controller uses straight alternating rows of switches which can be customized for different tunings by programming and with key overlay sheets. Bert Bongers built versions with 122 and 124 keys. Harvey Starr manufactures Wilson Microzone skewed row hexagonal key midi controllers in 248 and 810-key models that can be programmed and the key surfaces organized into generalized as well as many other arrangements. Dylan Horvath manufactures a 280-key MIDI controller with skewed hexagonal