Digital real time music synthesizer

Abstract

This disclosure pertains to a digitalized music synthesizer functioning in the real time domain to continuously update, in an asynchronous manner, a continuing approximation of a desired waveform by utilizing its memory of the recent history of the operation of the keyboard of the apparatus. A real time clock and a microcomputer are both driven by a single crystal oscillator, operating at any arbitrary frequency that need not correspond with the frequency of the fundamental or harmonic waves to be produced by the apparatus. A memory of the recent history of keyboard events is maintained. The microcomputer utilizes an algorithm employing square waves as a basis and a differential correcting technique which minimizes the quantity of square wave defining terms that need be computed by only recomputing at each time, corrections to the previous computation. The digitalized output, represented by summing the transient amplitudes comprising the updated approximation to the desired waveform, is fed into a digital to analog converter, an amplifier and a speaker system.