Complex waveform generator for musical instrument

A tone source apparatus for an electronic musical instrument comprising:

• a source of clock pulses having a period defining a unit time interval;
• memory means having a plurality of sequential addresses each storing an instruction defining a segment of a waveform, each of said instructions comprising at least first, second and third sub-instructions comprising respectively, a code representing the time duration measured in terms of a number of said unit time intervals, a code representing a value corresponding to at least the amplitude variation per said unit time interval and a code representing the direction of slope of the associated waveform segment;
• an address counter clockable for accessing said memory addresses in sequence;
• coincidence means for clocking said address counter in response to the occurrence of a number of said unit time intervals equal to the value of said first sub-instruction of the currently accessed memory address;
• latch means clocked in response to said clock pulses and having a data input and a data output;
• and
• adder-subtractor means operative for developing an output signal representing the sum of or difference between said second sub-instruction and said latch means data output in accordance with said third sub-instruction, said output signal being coupled to said latch means data input;
• whereby said latch means data output comprises a series of signal segments as defined by the contents of said memory.

In a tone source apparatus for an electronic musical instrument of the type having a sequentially addressed memory means storing a plurality of waveform segment defining instructions, each of said instructions including a component representative of a selected parameter of the associated waveform segment, the improvement wherein said memory means comprises:

• a first memory having a plurality of sequential memory address locations each storing one of said instructions including an address code representing said selected parameter component, at least some of said memory address locations storing identical ones of said address codes;
• means for sequentially addressing the memory address locations of said first memory;
• a second memory storing a plurality of said selected parameter components;
• and
• means coupling each address code stored at a sequentially addressed memory location of said first memory for addressing a single one of said parameter components stored in said second memory.

A tone source apparatus for an electronic musical instrument comprising:

• a source of clock pulses;
• memory means storing a plurality of waveform segment defining instructions, each of said instructions including a selected constant value step size component;
• means for addressing said memory means;
• multiplier means operable for selectively modifying the step size component of an addressed waveform segment defining instruction;
• control means for operating said multiplier means;
• means responsive to said addressing means for resetting said control means in response to each newly addressed waveform segment defining instruction;
• and
• counting means responsive to said clock pulses for developing an output count signal incrementally changing in value in accordance with said modified step size signal for producing a sequence of waveform segment signals each characterized by a desired inflection.