Morrison & Foerster
Computerized music system having software and hardware sound sources
 A musical sound generating apparatus creates a waveform to generate a musical sound according to performance information. In the apparatus, a first waveform generator is operable for creating a waveform. A second waveform generator is operable independently from the first waveform generator for creating a waveform. An input device provides performance information. A designating device designates at least one of the first waveform generator and the second waveform generator in correspondence with the provided performance information. A controller selectively operates the designated one of the first waveform generator and the second waveform generator to create the waveform according to the provided performance information. An output device generates the musical sound based on the created waveform. The second waveform generator, the input device, the designating device and the controller are integrated with each other to constitute a main part composed of a computer, while the first waveform generator alone constitutes a supplementary part which is separate from the main part and which is optionally installable in the computer. 
Yamaha Corporation
Hideo Masatada Masashi
Yamada Wachi Hirano