Electronic musical instrument for tone formation by selectable tone synthesis computations

In a real time keyboard polyphonic electronic musical instrument of the type in which a tone generator is time shared and in which consecutive phase angle information corresponding to selected keys is supplied in assigned time-division time slots, the improvement comprising:

• a set of circuits interconnectable by gates to perform consecutive different arithmetic calculations during each time slot utilizing the phase angle information supplied in that time slot,
• a computation control data generator means for supplying during each assigned time slot a respective set of computation control data signals for selectively operating said gates, said circuits thereby performing during each time slot a set of plural arithmetic computations so as to calculate the waveform amplitude for the note assigned to that time slot, for the sample point corresponding to said supplied phase angle information, and
• tone color selection means for causing said computation control data generator means to supply a selected one of a plurality of different sets of computation control data, each such set causing said circuits effectively to be interconnected in different ways so as to implement a different set of arithmetic computations and thereby produce a tone of different color.

An electronic musical instrument of the type in which a musical tone waveshape is generated in real time by computation of waveshape amplitudes at successive sample points identified by consecutive phase angle values, the improvement for implementing selectable tone color, comprising:

• a set of circuits interconnectable in response to control signals to perform different mathematical operations utilizing said consecutive phase angle values,
• a computation control data generator for providing to said circuits, during the time interval allotted for computation of each sample point amplitude, a set of control signals causing said circuits to be interconnected so as to implement a corresponding set of mathematical operations that comprise a tone synthesis computation, said circuits thereby computing the waveshape amplitude for said each sample point, and
• tone color selector means, cooperating with said data generator, for causing said data generator to provide to said circuits alternative sets of control signals, each of which sets causes said circuits to be interconnected differently so as to implement respectively different tone synthesis computations.