Digital music synthesizer

Claim 2

Apparatus for making music, said apparatus comprising: tone generating means operating to provide a variety of musical notes in response to respective predetermined combinations of control signals applied thereto; a register which comprises means for holding a plurality of bits of digital information in a given order, said held information being changeable according to a predetermined pattern in response to input signals applied tO said register; means for reading digital information held in said register at a plurality of selected points in said register; means for applying to said register at least a first input signal which is obtained according to a preselectable code from bits of information obtained from said plurality of points; means for applying to said register a second input signal which varies according to a predetermined periodic function thereby to cause the information held in said register to periodically change in a predeterminable sequence; and means for applying to said tone generating means control signals which vary as respective preselectable logical functions of the information held in said register thereby to cause said tone generating means to produce a sequence of notes, the pattern of which is a function of the changing information held in said register.

Claim 3

Apparatus as set forth in claim 1 wherein said register is a shift register.

Claim 4

Apparatus as set forth in claim 2 wherein said means for applying said one input signal includes a plurality of selector switches, each of which selects a signal from one of a predetermined plurality of stages of said shift register and logic gate means for combining the selected signals according to a predetermined binary logic function thereby to generate said first input signal.

Claim 5

Apparatus as set forth in claim 3 wherein said logic gate means comprises an EXCLUSIVE OR gate.

Claim 6

Apparatus as set forth in claim 3 wherein said means for applying a second input signal comprises an oscillator connected to said shift register to cause information held in said register to be shifted at a repetition rate which is related to the frequency of operation of said oscillator.

Claim 7

Apparatus as set forth in claim 1 wherein said register comprises a multistage counter and means for selectively providing digital feedback to selectively vary the pattern of states generated by said counter.

Claim 8

Apparatus as set forth in claim 6 wherein said means for applying a second input signal comprises an oscillator connected to said counter for causing said counter to be incremented through successive states at a rate which is related to the frequency of operation of said oscillator.

Claim 9

Apparatus as set forth in claim 1 wherein said tone generating means comprises means for selectively generating a plurality of note signals representing respective musical notes and gate means for passing a selected one of said note signals in response to said control signals.

Claim 10

Apparatus as set forth in claim 8 further including a plurality of selector switches each of which selects a signal from one of a plurality of predetermined stages of said register, said selected signals being applied to said gate means as said control signals.

Claim 11

Apparatus as set forth in claim 1 wherein said tone generating means comprises gate means operable to selectively change a note being generated and also comprises a plurality of selector switches each of which selects a signal from one of a plurality of predetermined stages in said register, said selected signals being applied to control said gate means.

Claim 12

Apparatus as set forth in claim 1 wherein said tone generating means comprises: a digital accumulator; means for generating a plurality of digital signals, one for each note to be generated, representing respective preselected binary numbers, the values of said binary numbers being in proportion to the note frequencies; means for selecting one of said digital signals and applying the selected signal to said accumulator; means for driving said digital accumulator to repetitively and periodically add the binary number represented by said selected digital signal to the sum number held in said accumulator; and means for generating an output signal which represents a selected carry bit in said sum number, whereby the base frequency of said output signal is proportional to the number represented by the selected digital signal anD thus also to the note frequency determined by said control signals.

Claim 13

Apparatus as set forth in claim 1 wherein said tone generating means comprises an oscillator and a multistage frequency dividing counter driven by said oscillator, said counter having a plurality of digital feedback paths, each of said paths having gate means for selectively rendering the respective path inoperative thereby to change the output frequency of the counter by a predetermined factor, said control signals being applied to said gate means to vary the note being generated as a function of the information held in said register.

Claim 14

Apparatus for generating a plurality of tone signals having a predetermined scalar frequency relationship, said apparatus comprising: means for generating a plurality of digital signals, one for each tone signal, representing respective preselected binary numbers, the values of said binary numbers being related in the same scalar manner as said tone signal frequencies; a digital accumulator; means for selecting one of said digital signals and applying the selected signal to said accumulator; means for driving said digital accumulator to repetitively and periodically add the binary number represented by said selected digital signal to the sum number held in said accumulator; and means for generating an output signal which represents a selected carry bit in said sum number, whereby the base frequency of said output signal is proportional to the number represented by the selected digital signal and thus also to a respective tone frequency.

Claim 15

Apparatus for generating a plurality of tone signals having a predetermined scalar frequency relationship, said apparatus comprising: means for generating a plurality of digital signals, one for each tone signal, representing respective preselected binary numbers, the values of said binary numbers being related in the same scalar manner as said tone signal frequencies; a digital accumulator; means for selecting one of said digital signals and applying the selected signal to said accumulator; means for driving said digital accumulator to repetitively and periodically add the binary number represented by said selected digital signal to the sum number held in said accumulator; and means for generating an output signal which represents a selected carry bit in said sum number, whereby the base frequency of said output signal is proportional to the number represented by the selected digital signal and thus also to a respective tone frequency.

Claim 16

Apparatus as set forth in claim 13 wherein said accumulator operates in a serial mode and said digital signals are generated in a corresponding serial format.

Claim 17

Apparatus as set forth in claim 14 wherein said means for driving said accumulator comprises an oscillator providing a clock signal at a preselected frequency and wherein said clock signal is applied also to said digital signal generating means for timing said serial format, whereby the pitch of said tone signals can be adjusted by varying the frequency of said oscillator while the relationship between the various tone frequencies is maintained.

Claim 18

Apparatus for making music, said apparatus comprising: a shift register for holding a plurality of bits of digital information in a given order; means for shifting data held in said register at a preselectable repetition rate; means for reading digital information held in said register at a plurality of selected points in said register; a first pair of selector switches each of which selects one signal from a predetermined plurality of stages of said shift register; logic gate means for combining the signals selected by said first pair of switches and applying to said shift register an input signal which is a predetermined logical function of the signals selected by said first pair of switches; means for generating a plurality of digital note signals representing respective preselected binary numbers, there being one digital signal for each of a plurality of notes to be generated, the values of said binary numbers being in proportion to respective predetermined musical note frequencies; a digital accumulator; selection gate means for selecting one of said digital note signals in accordance with a plurality of control signals applied to said selection gate means, the selected digital note signal being applied to said accumulator; a second pair of selector switches each of which selects one signal from a plurality of stages of said shift register, the signals selected by said second pair of switches being applied to said gate means as said control signals; means for driving said digital accumulator to repetitively and periodically add the binary number represented by said selected digital note signal to the sum number held in said accumulator; and means for generating an output signal which represents a selected carry bit in saId sum number, whereby the base frequency of said output signal at any given time is proportional to the number represented by the respective selected digital note signal and thus also to the respective note frequency and whereby the frequency of said output signal changes in a pattern determined by the setting of said selector switches.

Claim 19

Apparatus for making music, said apparatus comprising: a shift register for holding a plurality of bits of digital information in a given order; means for shifting data held in said register at a preselectable repetition rate; means for reading digital information held in said register at a plurality of selected points in said register; a first pair of selector switches each of which selects one signal from a predetermined plurality of stages of said shift register; logic gate means for combining the signals selected by said first pair of switches and applying to said shift register an input signal which is a predetermined logical function of the signals selected by said first pair of switches; means for generating a plurality of digital note signals representing respective preselected binary numbers, there being one digital signal for each of a plurality of notes to be generated, the values of said binary numbers being in proportion to respective predetermined musical note frequencies; a digital accumulator; selection gate means for selecting one of said digital note signals in accordance with a plurality of control signals applied to said selection gate means, the selected digital note signal being applied to said accumulator; a second pair of selector switches each of which selects one signal from a plurality of stages of said shift register, the signals selected by said second pair of switches being applied to said gate means as said control signals; means for driving said digital accumulator to repetitively and periodically add the binary number represented by said selected digital note signal to the sum number held in said accumulator; and means for generating an output signal which represents a selected carry bit in saId sum number, whereby the base frequency of said output signal at any given time is proportional to the number represented by the respective selected digital note signal and thus also to the respective note frequency and whereby the frequency of said output signal changes in a pattern determined by the setting of said selector switches.

Claim 20

Apparatus as set forth in claim 16 including means for counting selected events in the pattern of notes generated and for periodically modifying one of said control signals after a predetermined count thereby to provide a grace note.

Claim 21

Apparatus as set forth in claim 16 including means for counting selected events in the pattern of notes generated and for periodically, in response to the count, changing the repetition rate at which data is shifted in said register thereby to provide a change in tempo.

Claim 22

Apparatus as set forth in claim 16 including means for counting selected events in the pattern of notes generated and for periodically, in response to the count, changing the sample bit of the sum number in the accumulator thereby to change the pitch of the note sequence being generated by one octave.