The Keaton Music Typewriter was first patented in 1936 (14 keys) by Robert H. Keaton from San Francisco, California.
Another patent was taken out in 1953 (33 keys) which included improvements to the machine. It was marketed in the 1950s and sold for around $225.
The machine types on a sheet of paper lying flat under the typing mechanism.
The typewriter made it easier for publishers, educators, and other musicians to produce music copies in quantity. Composers, however, preferred to write the music out by hand.