Abstract: A frequency number corresponding to the frequency of a tone intended to be sounded is accumulated in an accumulator at every calculation timing of a constant interval to produce values progressing at a rate corresponding to the tone frequency. At this rate, waveform amplitude value samples are sequentially produced one after another in a tone producing section using the output of the accumulator as phase angle data. A reset circuit is provided in connection with the accumulator and this circuit functions to compulsorily reset the progressing values in the accumulator to its initial value in response to a carry out signal generated at the calculation timing when the phase angle data has reached its predetermined modulo value. Thus the period of progress of the phase angle data is harmonized with the calculation timing, i.e., the sampling timing.

Abstract: An electronic musical instrument has the switch contacts associated with the keyboard and with the other user operated controls arranged in a single matrix with the switch contacts being grouped in the matrix such that, for example, all of those switches associated with keys are in one corner of the matrix. This arrangement and grouping of switch contacts allows the matrix to be scanned, under the control of logic circuitry, such that those switch contacts associated with the keyboard keys are more frequently scanned than are those switches associated with the other inputs. Information for controlling an audio tone generator is provided in digital form as a function of the state of the contacts of the switches comprising the matrix, the audio frequency signals being digitally synthesized.

Abstract: In a electronic musical instrument wherein a portamento is played by supplying the pitch voltage corresponding to a subsequently depressed key to a capacitor holding the pitch voltage corresponding to a previously depressed key, the charge and discharge currents of the capacitor corresponding to the difference between the two pitch voltages are controlled to vary exponentially thus changing exponentially the capacitor terminal voltage. The terminal voltage of the capacitor is applied to drive a voltage controlled oscillator to vary its oscillation frequency. To vary exponentially the terminal voltage of the capacitor, a mutual conductance converter is connected between the capacitor and a keyboard section and the output current from the mutual conductance converter is controlled by a control signal corresponding to the terminal voltage of the capacitor.

Abstract: A musical tone is synthesized by controlling harmonic components of a note selected in a keyboard in accordance with a desired fixed formant. A parameter computation circuit detects a harmonic frequency which is nearest to a center frequency of the fixed formant and produces FM computation parameters using the nearest harmonic frequency as a carrier frequency and a fundamental or harmonic frequency of the selected note as a modulating frequency. A frequency modulation circuit performs an FM computation on the basis of these parameters and, as a result, a tone whose harmonic components have been controlled in accordance with a formant having the nearest harmonic frequency as a central component is synthesized. The parameter computation circuit computes frequency difference between the nearest harmonic frequency and the center frequency of the fixed formant for controlling the level of a formant synthesized in a frequency modulation circuit in accordance with this frequency difference.

Abstract: A harmony signal generating system for an electronic organ comprises a plurality of integrated circuit chips which each receive upper and lower manual keying signals for two consecutive organ notes. A first read only memory (ROM) generates octave identify signals to designate the octave of an active upper manual note. A second ROM generates octave select signals which are combined with the octave identify signals in a third ROM to generate the harmony signals which comprise the lower manual chording signals played through the upper manual within a twelve note range above an active upper manual note and an upper manual note which is one octave above the active upper manual note. The octave identify signals are provided in parallel among the chips from the chip having the lowest active upper manual letter note. Upper manual active signals generated in response to the upper manual keying signals are connected in series among the chips to select the appropriate chip.

Abstract: An electronic keyboard musical instrument comprising a multiplexed keyboard and a programmable microcomputer interfaced between the keyboard and a system of capture tone generators. The loading circuitry for the microcomputer, which is interposed between it and the keyboard multiplexer output, monitors the serial data stream and transmits only key change information to the microcomputer. If a keydown signal appears in a time slot where that time slot was previously empty, a multiple bit binary word identifying that time slot and indicating that it is a keydown condition is transmitted to the microcomputer. Similarly, if a keydown pulse disappears from a time slot when a pulse was previously present, a similar code is transmitted to the microcomputer indicating that the key is no longer depressed. The microcomputer controls the assignment and deassignment of tone generators for the accompaniment, solo and pedal manuals based on the key change information transmitted to it.

Abstract: A digital synthesizer primarily intended for use in electronic musical instruments which are microprocessor controlled includes a plurality of storage devices which contain numerical data commensurate with the characteristics of an output signal to be produced. Information is read out of these storage devices under the control of command signals having a predetermined repetition frequency. The generation of the command signals is controlled in such a manner as to permit the generation of harmonically related frequencies.

Abstract: An electronic musical instrument comprises a plurality of key switches and a key switch scanning circuit for sequentially scanning said key switches at a predetermined speed to produce time division multiplexed key data signals representing the depressed states of respective keys. The instrument further comprises a time division multiplexed tone waveform generating circuit which generates tone signals on a time division basis and in synchronism with the scanning of said key switches, said tone signals consisting of waveform samples of all the notes, i.e. tone frequencies, that the instrument can generate, and means which delivers out the output signal from the time division multiplexed tone waveform generating circuit at the moments when said time division multiplexed key data signals arrive, thereby producing plurality of tone signals in a time division multiplexed manner.

Abstract: An electronic organ has a digital control circuit with a sampling circuit (3) which generates key identification signals (B) in the form of pulse series wherein the pulses denote the actuated keys (2) of the keyboard (1). Such pulses cause a tone selector or evaluating circuit (12) to transmit tone signals to a voicer circuit (15). A shift register (16, 116 or 216) is provided to delay the key identification signals so that the tone signals which the voicer circuit receives do not correspond to those normally expected on actuation of certain keys. The non-delayed key signal can be superimposed upon the delayed signal or signals (V1, V2) in a suitable summing circuit (17) to thus achieve transpositions, interval couplings and other tonal effects.

Abstract: In a musical instrument having a solo and accompaniment keyboard apparatus is provided whereby an accompaniment tone color is selected which adaptively complements selected solo tones. The first zero crossing spacing of the autocorrelation function for the solo tone is used to implement a tone selection logic. An effective zero crossing is computed for combinations of available accompaniment tones. An accompaniment tone combination is selected whose effective zero crossing has a maximum value that does not exceed a complemented value of the zero crossing for the selected solo tone.

Abstract: Polyphonic sound may be produced through the use of a tone generator which divides the high frequency output of a clock pulse generator by numbers which are allocated to individual keys or pedals of an instrument. The divisor values are stored in main and intermediate memories, the values in the intermediate memory subsequently being counted down to zero. An output signal, for control of a sweep voltage generator, is produced which is a function of all of the divisor values in the intermediate memory at any one time.

Abstract: An electronic musical instrument sequentially calculates a plurality of partial tone signals which are amplitude-modulated by a plurality of time window signals, on the time division basis, such that these partial tone signals are synthesized to form a musical tone signal. The instrument includes a circuit means for producing a plurality of predetermined time window signals, an another circuit means for producing a plurality of predetermined partial tone signals and modulating means for modulating the partial tone signals with the time window signals on the time division basis. This instrument makes it possible to form a musical tone having a great number of harmonic components with a simple circuit construction.

Abstract: An electronic organ circuit includes a multiplicity of keyers receiving control inputs from plural shift and store registers capable of operating any given keyer at different levels. The inputs for a given keyer are applied on a cyclic basis and for differing time periods in such manner that the keyer's output amplitude and waveshape vary in response to the number and duration of inputs. A processor responsive to keyboard key and stop actuation supplies information to shift register chains corresponding bit-wise to the operation of keyboard keys, and corresponding, in respect to bits destined for a given register, to the condition of organ stops. Individual registers are then operated on a duty cycle basis and provide outputs of selected duration for effecting different stop sounds.

Abstract: A programmable tone generator for an electronic musical instrument generates a tone signal having a desired fundamental frequency and harmonic content. A binary counter serves as a time base for encoding each period of a tone signal waveform onto plural outputs in the form of a binary code. A plurality of programmable tone generation circuits are coupled with selected counter outputs to comprise plural tone signal branches, each providing a tone signal at a selected fundamental frequency and having selected harmonic content. A signal processing circuit associated with each tone signal branch includes a programmable variable code generator and determines the initial content of the output waveform, subsequently either maintaining or changing the fundamental frequency and harmonic content thereof.

Abstract: The present invention relates to a process and apparatus for use in musical instruments. In particular, the invention is useful for identifying a chord played on a keyboard of a musical instrument, such as the accompaniment manual of an electronic organ, and for identifying the root and the type of chord being played. Pursuant to the invention, a microprocessor used in conjunction with the instrument selectively causes the associated circuitry of the pedal and/or accompaniment keyboard of the musical instrument to play automatically in an appropriate octave either the identified root or a sequence of notes which is compatible with the identified root and chord. A pedal override feature is also provided which overrides the chord identification invention when the musician plays one or more pedal notes.

Abstract: A multiple octave generator system for providing tones in an electronic organ permits the production of both ensemble and celeste effects by providing the appropriate amounts of detuning among cascaded ranks of divide-by-two locked octave type tone generators. The generator system programs from the ranks adjacent octaves of generator into groups having slightly overall stretched tuning which, when combined with an unstretched rank, closely resemble pipe organ celeste tuning. This permits the celeste beat rate of the lower octaves to be increased to a more desirable rate without causing the beat rate of the upper octaves to become too fast.

Abstract: A signal processing system records and reproduces a music signal which varies repeatedly. The music signal is sampled at a given sampling period and pulse row obtained from the sampling is rearranged into a given pattern to achieve a new pulse row which is stored. For read out from a storage medium, a read-out means reproduces the original pulse row sequence and provides a wave form of the original music signal.

Abstract: In a musical instrument having one or more tone generators in which a plurality of data words corresponding to the amplitudes of a corresponding number of evenly spaced points defining the waveform of one cycle of a musical signal are transferred sequentially from a note register to a digital-to-analog converter in repetitive cycles at a rate proportional to the pitch of the tone being generated, apparatus is provided for producing tones having independent time-varying harmonic components. A recursive algorithm is implemented which approximates prespecified harmonic-time curves by piecewise segments of exponential functions. Only a small number of stored curve parameters are required to generate the harmonic-time scale factor for a set of harmonic coefficients.

Abstract: An electronic musical instrument of a channel assignment type wherein depressed keys from among a larger plurality of keys are respectively assigned to a smaller plurality of tone producing channels for generating wave of musical tones. The assigner comprises a microprogram, an arithmetic section, a memory, and an interruption control circuit to assign the depressed keys to available tone producing channels. The current on-off information of the keys is subjected to calculation to form a key-on request file and a key-off request file. A tone request file is formed on a plurality of tone data as designated by the tone levers. A channel assignment table is formed, based on the key-on and key-off request files, to indicate a status of assigning the depressed keys to the tone producing channels.

Abstract: There are provided a circuit for producing a fundamental wave and harmonic components thereof, an amplitude coefficient generator for generating amplitude coefficient respectively corresponding to the harmonic components, a multiplier for multiplying an output of the synthesizer with an output of the amplitude coefficient generator to obtain products, and synthesizing means for synthesizing the products for forming a musical tone. The synthesizer comprises an increment component generator, and an accumulator for accumulating the increment component, thereby forming amplitude coefficients for the harmonic components.

Abstract: An electronic keyboard musical instrument comprising a multiplexed keyboard and a programmable microcomputer interfaced between the keyboard and a system of capture tone generators, and including means for causing phase locking between the tone generators. The loading circuitry for the microcomputer monitors the serial data stream and transmits only key change information to the microcomputer. The microcomputer controls the assignment and the assignment of tone generators for the accompaniment, solo and pedal manuals based on the key change information transmitted to it. In order to avoid cancellation between tones which are in octave or multiples thereof apart, the tone generators for each manual are phase locked with the other tone generators for that manual. Not only are the top octave synthesizers for each tone generator phase locked, but the divider strings are uniformly loaded so that they operate in identical states.

Abstract: The phase of digitally synthesized audio frequency signals of the same frequency is synchronized prior to conversion of the signals into analog form. The phase synchronization is accomplished, in a musical instrument of the keyboard type, by comparison of the digitally coded signals which are commensurate with all of the simultaneously generated input commands and, when frequency coincidence is detected, employing the phase value of the first of plural commanded signal at the same frequency as the starring phase value for subsequently generated signals at the common frequency.

Abstract: A multiple language electronic keyboard system is disclosed for generating and modifying musical note information. The system includes a plurality of manually activated switches arranged in a matrix of rows and columns with the switches sufficiently close to allow a single finger of the user to activate a plurality of switches in a single stroke. A decoder detects and distinguishes between a first language and a second language of distinct switch activation patterns. Musical note information is generated by a processor which receives information from the decoder concerning the location of each activated switch and the language detected by the decoder. The versatility of this system is further enhanced by the addition of envelope and tone generators and also by visual display devices. In the preferred embodiment the keyboard is arranged to positionally and operationally emulate a guitar fret board.

Abstract: In an electronic musical instrument of the waveshape memory type including at least one waveshape memory for storing and reproducing sample values of a musical sound wave to be generated, the waveshape memory stores the sample values of the complete waveshape of a musical tone with a shaped envelope.

Abstract: A root note detection circuit detects the highest or lowest key among depressed keys in an accompaniment key range as a root note designation key. A root note memory stores the detected root note data and rewrites its storage each time the detected root note data changes. A chord type detection circuit detects a chord type in accordance with states of depression of keys other than the detected root note designation key in the accompaniment key range. The detected chord type data is stored in a chord type memory by being controlled by outputs of a root note change memory and a new key detection circuit. The root note change memory detects change in the root note by comparing the output of the root note detection circuit with the output of the root note memory and outputs a root note change signal during a preset waiting timing. Accordingly, the data stored in the chord type memory can be rewritten not only upon detection of depression of a new key but during this waiting time.

Abstract: An electronic musical instrument has a generator assigner for supplying note data and octave data by key stroke entry, a top octave synthesizer for generating 12 of the highest pitch signals for each note, a circuit for selecting one highest pitch signal from the 12 highest pitch signals according to note data, a binary counter for dividing one highest pitch signal to produce several pitch signals, and circuits for selecting one pitch signal out of several pitch signals obtained by the binary counter. The circuits are further controlled by both octave data and note data to generate octave series tone signals and non-octave series tone signals such as quint series tone signals.

Abstract: A system for extracting the fundamental frequency or pitch of complex waves such as voice, musical instruments or other audio signals. Separate channels extract the fundamental frequency component when it is present in successively wider frequency bands, the frequency intervals between which are equal or less than an octave. Control signals generated in response to the presence of the fundamental components in any lower frequency channel inhibit each of the higher frequency channels thereby reducing the possibility of an overtone being detected as a fundamental frequency component of the complex wave.

Abstract: An electronic musical instrument includes a plurality of address generators for producing address signals corresponding to different tones each varying at a rate synchronous with the frequency of each of the different tones, a waveform memory device including a plurality of addresses for storing at respective addresses a plurality of waveform sample values that constitute a waveform, a circuit for sequentially supplying one after another of the address signals to the waveform memory device to read out the waveform in different rates in a time division multiplexed manner for different tones, and musical tone forming circuits for forming musical tones in accordance with the time division multiplexed waveform outputs of the waveform memory device.

Abstract: An electronic organ having a scanned keyboard manual (10) includes a keyboard latch (24) interposed between the scanning apparatus (12) and the organ keyers (26). The keyboard latch (24) comprises a gate (42) for comparing the serial data pulses, each of which represents a respective depressed key, produced at the output of the scanning apparatus (12) during each scan of the keyboard manual (10) with the serial data pulses produced during the immediately preceding scan for developing a control signal representing the detection of a depressed keyboard key during the on-going scan which was not depressed during the immediately preceding scan. An output circuit (52, 54, 56) is provided for continuously developing an output signal reflecting the keys depressed during the last scan in which a control signal was developed whereby the tone signals corresponding thereto are continuously sounded even though the keys have subsequently been released.

Abstract: Apparatus for producing a chorale or vocal effect in an electronic musical instrument comprises means responsive to the playing keys of the instrument for producing an indexing signal and means responsive to the indexing signal for sequentially developing a plurality of control signals. A programmable filter is responsive to each sequentially developed control signal for modifying the harmonic content of a tone signal to simulate a different vowel-like sound for producing a vocal effect consisting of a sequence of different vowel-like sounds as the keys are played. The modified tone signal may be coupled through a chorus generator to simulate a chorale effect and the programmed characteristics of the filter may be modulated to further animate the performance as well as being made responsive to a glide signal for producing two different vowel-like sounds in succession at two different pitches in response to a glissando or portamento command.

Abstract: An electronic musical instrument in which a single manual keyboard is provided with two voicing blocks which has a certain keyboard space interval therebetween and at least one of which generates a multiple tone corresponding to keys being depressed. There is provided a circuit for providing a certain time interval from a time-divided signal produced by the key depression. This circuit distinguishes between tones from the two voicing blocks, to thereby separate them from each other. There is also a circuit for generating a monophonic or polyphonic tone signal from each of the separated time-divided signals.

Abstract: In a wave generator for an electronic musical instrument, a plurality of sampling values of a musical tone waveform having a given envelope are simultaneously carried out in a time division system according to the musical tone waveform calculation sequence which can be varied as required; more specifically, calculation for generating a musical tone waveform is carried out while advancing phase, the envelope given to the musical tone waveform is divided into plural segments whose time intervals can be changed as desired, and phase increment values are set for the segments thus obtained while increment values are set for the phase increment values, respectively, these values being accumulated to carry out the calculation of the musical tone waveform, whereby the musical tone waveform and its envelope are varied intricately to produce musical tones rich in natural feeling.

Abstract: By providing as circuit activators flexible, intentionally damped, vibratory elements, for example strings, the resonant frequency of which may be unrelated to the tone to be generated, while utilizing electronic circuits controlled by such flexible elements for tone generation and modulation, the instrument according to this invention provides a range of "voices," attack, sustain and decay envelopes and other tonal characteristics which cannot be achieved with conventional mechanically resonant systems (such as are found in an acoustical guitar) while providing the performer with the tactility and dynamic expression with which he can identify.

Abstract: An electronic organ, particularly of the institutional type employing classical voicing, having Swell and Great manuals as well as a full pedalboard wherein the manuals and pedalboard are multiplexed simultaneously to produce a plurality of synchronized serial data streams. Intermanual coupling is accomplished by connecting the data stream from one manual to the footage generation circuit of another manual, and tab footages are generated for each manual by utilizing tapped shift registers introducing controlled amounts of delay of the keyboard data before demultiplexing thereof. There is a bank of demultiplexer-keyers for each voice, such as flutes, principals, complex and percussion, which receive the serial data streams from one or more of the footage generators. The demultiplexer-keyers are supplied with tones and function to demultiplex the serial data streams and provide tones selected in accordance with the keydown pulses in the serial data streams to the voicing circuitry.

Abstract: A new, performer played, real time, multitonal, multitimbral musical instrument consists of speed and force sensitive keys in which time domain multiplexing is used to find and associate one and only one tone generator, not otherwise busy, with any key that is depressed. The sound generator disclosed can provide very realistic simulations of the flute, oboe, trumpet, French horn, trombone through the provision of various types of modulations in amplitude and frequency of the various partials, as is characteristic of each instrument simulated, and filtered noise. Glissandi are provided from one note to another and are controlled from the pair of keys involved by the relative pressure with which they are depressed. For the nonpercussive tonalities, the speed with which a key is depressed, which is determined by differentiating the force, may be used to cause the attack transient to behave in a manner very characteristic of the instrument being simulated.

Abstract: An electronic organ, particularly of the institutional type employing classical voicing, having Swell and Great manuals as well as a full pedalboard wherein the manuals and pedalboard are multiplexed simultaneously to produce a plurality of synchronized serial data streams. Intermanual coupling is accomplished by connecting the data stream from one manual to the footage generation circuit of another manual, and footages are generated for each manual by utilizing tapped shift registers introducing controlled amounts of delay of the keyboard data before demultiplexing thereof. There is a bank of demultiplexer-keyers for each voice, such as flutes, principals, complex and percussion, which receive the serial data streams from one or more of the footage generators. The demultiplexer-keyers are supplied with tones and function to demultiplex the serial data streams and provide tones to the voicing circuitry selected in accordance with the keydown pulses in the serial data streams.

Abstract: A digital electronic organ mixture system comprises a pair of digital organs operatively connected in parallel to the same keyboard or keyboards. The keys are grouped into regions of adjacent keys. In one of the parallel organ systems, the frequency numbers ascend along the keyboard corresponding to the notes associated with the keys. In the other parallel organ system, the frequency numbers are weighted by preselected factors, the factor being the same for each keyboard region, and the factor for each successive region along the keyboard being lower than the factor for the immediately preceding region. Activation of a key along the keyboard produces a pitch series comprising a note produced by the unweighted frequency numbers in one organ system and a second note produced by the weighted frequency numbers in the other organ system. The pitch series breaks back at each successive keyboard region in accordance with the weighting factor for that region.

Abstract: Digital semiconductor circuit having a plurality of control inputs addressed via a keyboard corresponding to the number of keys on an organ keyboard, as well as having a plurality of audio signal inputs addressable by an oscillator arrangement with periodic electrical oscillations, each control input being permanently assigned to a key of the keyboard and each audio signal input of an audio frequency, and further having respective audio frequency outputs provided for driving an electroacoustical transducer, the control inputs being addressable by control signals corresponding to the logic levels, including a clock-controlled shift register operated as a parallel-to-series converter and having respective cells to which the respective control inputs are assigned, the shift register having a signal output, a switching system controllable by the signal output of the shift register and by clock pulses provided for the operation of the shift register, the switching system having the totality of the audio signal inp

Abstract: A key switch information assignor having a data processor unit which produces keyboard and octave codes which serve to poll and interrogate a keyboard circuit. In response to the polling, the keyboard circuit produces key information representing the depression and release of keyboard switches in the keyboard circuit. This key information is compared by the data processor unit with previous key information to determine an event of key depression or release. In response thereto, a note code is determined combining the key information with the keyboard and octave codes. The key code is then sent to an assignment memory for further use. An envelope generator is provided which sends signals to the data processor unit to indicate the end of note sounding and thereby release of the key code from the assignment memory. Special arrangements are made for high speed release when a demand signal is generated in the case of all channels of the assignment memory being utilized.

Abstract: A tone generator system for electronic musical instruments includes a voltage-regulated, high-frequency oscillator. The output of the oscillator is connected with the inputs of first and second 12-tone divider circuits having outputs for transmission of full octaves of tone signals. The connection between the output of the oscillator and the input of one of the divider circuits contains circuitry which intercepts each n.sup.th signal of the series of signals transmitted by the oscillator so that the one divider circuit is out of tune with the other divider circuit. The number n can be varied by a battery of switches and can be as low as 2 or higher than 128. An auxiliary signal dividing circuit can be connected between the output of the oscillator and the input of the other divider circuit.

Abstract: An electronic musical instrument equipped with multiple musical tone signal generating channels, with an automatic play system which controls the tone generation of the musical tone signal generating channels on the basis of the automatic play data recorded in a memory so as to successively and automatically generate musical tones. The instrument also has a manual play system which controls the tone generation of the musical tone signal generating channels by the keyboard and other performance controls so as to generate musical tones by control of the tone generation of the multiple musical tone signal generating channels by the joint use of the automatic play system and the manual play system.

Abstract: A sequence of timing signals is generated having a time spacing corresponding to the average spacing between successive actuations of a control switch. The system automatically starts a new calculation if the control switch is actuated at least two times with a time spacing less than some prespecified threshold time. The data input process is self-terminated when a time interval equal to the threshold time expires after an actuation of the control switch. The generated sequence of timing signals can be used as the metronome clock for an automatic rhythm generator.

Abstract: The tone production system for an electronic musical instrument comprises depressed key detection means for outputting pulses at a timing corresponding to a key depressed by time division timings assigned to each note, a shift register for shifting successively said pulses outputted from said depressed key detecting means in synchronism with said time division timing, key data forming means for taking out each output pulse of predetermined plural stages of said shift register in accordance with a desired type of chord, musical tone production means for producing each of plural musical tone signals of notes corresponding to pulse generation timings in accordance with each pulse taken out by said key data forming means.

Abstract: A chord generating apparatus of an electronic musical instrument is provided with a selector which selects a single key among a plurality of depressed keys, a detector for detecting a chord type according to types of keys other than the selected key, and a musical tone signal forming circuit for forming a musical tone regarding a chord determined in accordance with outputs of the selector and detector.

Abstract: A very inexpensive computer input device for music information includes a piano-type keyboard unit adapted to be fastened on to a standard alpha-numeric computer keyboard so that manual "playing" of music on the piano keyboard results in actuation of alpha-numeric keys and the recording of the music in the computer memory, for later playback in audible form, or print-out in sheet music form.

Abstract: The portable keyboard musical instrument employs two hollow tubes with either keyboards in each or one keyboard and one button cord unit, connection means at either end, a collar means with which to secure the two tubes and end caps to close off the non-connected ends. The instrument weighs only a few pounds and can be carried by the player much like a guitar when connected end to end, or like an accordian when connected side by side. The sound which can be obtained is only limited by the desired electronics and the instrument can be connected to the amplifiers by cable or remote.

Abstract: An electronic musical instrument comprises a note code producer for producing note codes respectively having n bits representing juxtaposed notes aligned by a semitone interval step. The note codes to be generated are selected from a binary code table consisting of successively aligned binary values corresponding to an order of alignment of the notes in a musical scale and the table omits either one of the largest and smallest values to be represented by the lowest m bits (n>m). A modified note code generator produces modified note codes by repetitively adding the lowest m bits of each note code to further lower order digits below the least significant bit of each note code, and a sound system generates musical tones having frequencies corresponding to the modified note codes.

Abstract: An apparatus (10) for transforming digital data stored in a memory (18) into sounds is disclosed. The apparatus includes an oscillator (12) which drives an address selector (14). The address selector drives the memory. A note generator (20) generates an analog electrical signal responsive to the memory, and a speaker with its associated amplifier stages (22) produces sounds corresponding to the analog electrical signal.A preferred arrangement of the note generator includes an inverting amplifier which can simply be a logic gate (44) and a plurality of resistors (50) selected by switches (56) in feedback relationship with the amplifier.A preferred arrangement includes a duty cycle selector (80) to produce harmonics of the fundamental frequency of the analog electrical signal.

Abstract: The electronic musical instrument is provided with a tone production means having tone production channels less than the total number of keys, a performance mode change detecting means, and a means for controlling tone production assignment of the tone production channels.The tone production assignment is controlled by depressed keys to one of the detecting means to produce a tone from one of the channel groups grouped according to the output of the detecting means. The selected tone production channel corresponds to the key group which the depressed keys belong to.

Abstract: A tone production assignment circuit produces control information representing assigned key code, key-on etc. Such information has a large number of bits with respect to each channel. A multiplexing circuit has output lines the number of which is smaller than the bit number of the information and divides the information with a plurality of time slots with respect to one channel. The multiplexing circuit is controlled by a signal from a timing signal generation circuit. The multiplexing circuit is capable of rearranging information for transmitting information required for the respective individual channels and also capable of inserting a timing data in an available time slot. A multiple data analysis circuit decodes the information provided by the multiplexing circuit. Tone generators are provided for the respective channels and each one of them functions to latch only corresponding information among the decoded information by a latch circuit.