Abstract: An attachment for installation upon a typewriter for applying musical notations to a sheet material and comprising a frame pivotally mounted on the typewriter body, the frame including a bridging member at one end of the frame adjacent the platen of the typewriter and a secondary keyboard at the opposite end of the frame. The bridging member carries rotatable, axially parallel cylindrical members spaced along the length thereof and oriented generally vertically to engage plural rollers oriented axially parallel to the platen and engaged thereagainst. The secondary keyboard carries individual keys, each having depending stems selectively engageable with a spring biased lever when a selected one of said keys is depressed. The keys each represent an imprinting location on a musical staff for application of the musical characters controlled by the principal keyboard of the typewriter.

Abstract: In a key-operated machine in which actuation of a key moves code elements of an associated code card into the path of a photoelectric sensing system, each code card is moved by a drive mechanism so as to cause the code elements to traverse the sensing system path only once, and at a speed which is independent of the speed of key movement, in response to each key actuation.

Abstract: A key in a keyboard for programmable computers, having its farther end recessed to form a nail-sparing shelf for carrying an exchangable mark or indicia. According to the invention the shelf serves as a seat for a flat and transparent pocket for receiving a removable lable carrying said mark, and having its insert opening blocked by the inner edge of the shelf.