An interactive graphics system for computer-assisted musical composition

The essential components of an ideal facility for computer-assisted musical composition and research are briefly described. More detailed consideration is given to the central role of a graphical display unit in such a system. The display acts as a control unit, provides a visual representation of the music score for editing, and allows the user to initiate music transformations and specify arrangements of submelodies. Some transformations and arrangements of the sort commonly used in composition are described, including transposition, inversion, retrograde, augmentation, and diminution. Design of an efficient, compact, and flexible data structure for a computer-aided music facility is undertaken. The proposed structure is a combination of pointer vectors and linked lists. A portion of the proposed system has been implemented on the CDC GRID display computer interfaced to an IBM 360/67 at the University of Alberta. The implementation focuses on the seldom met needs of the composer with respect to the symbolic medium and hardware through which he interacts with the computer during the composition process. The command language implemented to assist the composer is described and illustrated. The implementation seeks to demonstrate the feasibility and value of providing traditional music symbols on a graphical display unit as the central component of a computer-aided music facility.