Rodgers Instrument Corporation

Roland Corporation

Paul H Sharp

An electronic musical instrument having fewer note generators than notes stores in a sequentially addressable memory different waveform segments corresponding to different sounds. The note generators are time multiplexed by a processor, and use end addresses of current waveform segments to determine whether each current sample to be read is within the desired waveform segment. This limits the ability to noiselessly and rapidly move between segments. It is accommodated by storing a copy of the waveform segments in a readily shifted direction for immediate playout and subsequent shift to the destination waveform segment while reading the copy. This allows for cluster switching and scanning of waveform cycles to control a modulation of the base note, such as attack or tremulant, independently of the base note pitch.

Method and apparatus for reading selected waveform segments from memory

An electronic musical instrument has a plurality of oscillators. Each oscillator reads out segments of a waveform stored in memory using a random selection method. In one method the loop or start address is selected at random and the selection of a new address may be one cycle from the loop address or may be a repeat of the prior end address. In another method, both the loop and end addresses are randomly selected. Further, the end address is repeated a number of times determined randomly within a defined range of numbers.

Method and apparatus for randomly reading waveform segments from a memory

A mathematical function-generating device for producing, in an electronic musical instrument, functional values from an accumulation of first digital data. A digital data-generating circuit generates first digital data. A digital value string-generating circuit generates a bit-reversed digital value which increments a predetermined amount each time a first digital data unit is generated and which corresponds to a predetermined number of least significant bits in said first digital data unit. An adder is provided for adding the first digital data to a digital value comprising an accumulated value truncated to a predetermined number of least significant bits and having the bit reversed digital data concatenated thereto, thereby producing a new accumulated value. A memory is provided for storing and truncating each new accumulated value. The memory also supplies the adder with the new accumulated value. The first digital data corresponds to gradients of a linear or exponential curve and may be used as address signals to read waveform data from a memory. The accumulated values give functional values of that curve, which may represent an envelope waveform.

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Aloha, OR, United States of America

Paul H Sharp