Abstract: A method of entering an audio signal into a data processing apparatus, in which analog audio signals of at least two channels as the audio signal are digitized by and transmitted from an audio signal output device on a side of an audio source to an audio signal input device on a side of the data processing apparatus. A clock signal is supplied from the audio signal input device to the audio signal output device. The audio signal output device performs delta-sigma (.DELTA..SIGMA.) modulation on the analog audio signals of at least two channels so as to convert each of the analog audio signals of at least two channels into one-bit digital audio data for each of the at least two channels, based on the clock signal supplied to the audio signal output device. The one-bit digital audio data for the each channel is alternately selected based on the clock signal, to perform time-division multiplexing on the one-bit digital audio data for the at least two channels, to thereby produce one-bit multiplex audio data.

Abstract: In a case where tone waveform sample data are to be arithmetically formed by software, there are installed, within a virtual device driver routine of an operating system, a MIDI processing routine for converting a received MIDI event into tone generator control data and a waveform forming processing routine for arithmetically forming tone waveform sample data for one frame. The MIDI processing routine is triggered by a software interrupt signal that is generated in response to a MIDI event produced from an application software program such as a sequencer software program, and the waveform forming processing routine is triggered by a hardware interrupt signal that is generated upon completion of tone reproduction for one frame.

Abstract: Each of microcodes 1 has an interrupt prohibit bit 10 that specifies acceptance or nonacceptance of an interrupt request. Upon occurrence of an interrupt request, a processor refers to a value set in the interrupt prohibit bit 10 of the microcode 1 being currently executed. When "0" is set to the interrupt prohibit bit 10, the processor accepts the interrupt request, and when "1" is set to the interrupt prohibit bit 10, the processor rejects the interrupt request and starts executing a succeeding microcode. This allows the processor to safely execute certain instructions without interruption, as indicated by the interrupt prohibit bit 10 contained in the microcode 1 being currently executed.

Abstract: In a case where tone waveform sample data are to be arithmetically formed by software, there are installed, within a virtual device driver routine of an operating system, a MIDI processing routine for converting a received MIDI event into tone generator control data and a waveform forming processing routine for arithmetically forming tone waveform sample data for one frame. The MIDI processing routine is triggered by a software interrupt signal that is generated in response to a MIDI event produced from an application software program such as a sequencer software program, and the waveform forming processing routine is triggered by a hardware interrupt signal that is generated upon completion of tone reproduction for one frame.

Abstract: A digital signal processor has an arithmetic operation device that carries out arithmetic operations. The arithmetic operation device has a plurality of elementary arithmetic operation units. A signal path-forming device forms signal paths for inputting and outputting signals to and from the elementary arithmetic operations units, according to a predetermined program. The arithmetic operation device carries out processing of a digital signal input to the digital signal processor after the signal paths have been formed by the signal path-forming device.

Abstract: A musical tone waveform sample is generated at each sampling time by the use of a processing unit carrying out an arithmetic operation every repetition period that is longer than the sampling time. An envelope characteristic of a waveform of a musical tone to be generated is approximated by a polygonal line formed by a plurality of segments each of which has a length corresponding to the repetition period. An envelope value of a first waveform sample of waveform data of the musical tone to be generated for the repetition period is determined. The envelope value of the first waveform sample is multiplied by a predetermined attenuation factor to obtain an envelope value of a last waveform sample of the waveform data for the repetition period. Each of the segments of the polygonal line is determined by the envelope value of the first waveform sample and the envelope value of the last waveform sample. A difference between the envelope values of the first and last waveform samples is calculated.

Abstract: A musical tone-generating method and apparatus therefor are provided. Musical tones are generated by reading waveform data from a waveform table at a predetermined sampling frequency and carrying out arithmetic operations on the waveform data read from the waveform table to generate musical tone waveform samples, by the use of a processing unit. A first sampling frequency or a second sampling frequency lower than the first sampling frequency is selected as the predetermined sampling frequency. Interpolation of the waveform data read from the waveform table is effected by a second interpolation method which is lower in accuracy than a first interpolation method employed when the first sampling frequency is used, or alternatively the interpolation is inhibited, when the second sampling frequency is selected as the predetermined sampling frequency.

Abstract: A music system is comprised of a subsystem and a main system. The subsystem includes a first musical tone-synthesizing device that synthesizes musical tones, based on performance data externally supplied thereto, and a mixing device that mixes together the musical tones synthesized by the first musical tone-synthesizing device and external musical tones externally generated and supplied thereto. The main system includes performance data-processing device that controls performance data indicative of musical tones to be performed and transmits the performance data to the subsystem at predetermined timing, and a second musical tone-synthesizing device that synthesizes musical tones, based on the performance data, when the first musical tone-synthesizing device is in a predetermined state. The main system transmits the musical tones synthesized by the second musical tone-synthesizing device to the subsystem, as the external musical tones.

Abstract: An electronic circuit with an operation self-control function includes an electronic circuit body. A temperature sensor and a temperature-setting circuit detect the temperature of the electronic circuit body as an operating parameter indicative of an operating condition of the electronic circuit body, and a clock/peripheral circuit control circuit operates to restrict the operation of the electronic circuit body according to the detected temperature, to thereby restrain heat generation of the electronic circuit body.

Abstract: A music system has a main system and a subsystem. The subsystem synthesizes musical tones, based on waveform data supplied from a cache memory as a temporary memory device, transfers waveform data stored in the cache memory in predetermined blocks to a tone generator according to progress of musical tone synthesization by the tone generator, sequentially stores next blocks of externally supplied waveform data in the cache memory at areas thereof which have become empty after the data transfer, and mixes together the musical tones synthesized by the tone generator and musical tones supplied from the main system. The main system includes a waveform memory and synthesizes musical tones, based on waveform data supplied from the waveform memory.

Abstract: A modulator-demodulator (i.e., modem) permits a personal computer and the like to receive and transmit data in digital format across voice-oriented communications links such as telephone lines. A full-duplex-type modem employs a decoding device decoding the data which are subjected to convolution-encoding operation and amplitude-phase modulation. That data is subjected to amplitude-phase demodulation at first: and then, it is subjected to viterbi decoding by which an error correction is carried out. In the amplitude-phase demodulation, an amplitude-phase plane is employed and is divided into a plurality of areas in accordance with an arrangement of signal-placing points which is used by the amplitude-phase modulation. When receiving the data, a certain receiving point is defined. Then, one of the areas to which the receiving point belongs is determined; and its area information is produced.

Abstract: The automatic gain controller is comprised of a multiplier for multiplying an input signal by a given AGC multiplication factor to produce an output signal. An adder is provided for subtracting a target value from the output signal and adding an integrated value of an error value from the adder to the output signal to produce error value. An integrator to compute the integrated value of the error value from the adder. An operator is provided for computing a compensation value based on the error value according to a predetermined polynomial. An accumulator is provided for producing said AGC multiplication factor according to the compensation value. The automatic gain controller is composed of a digital signal processor specifically programmed to functionally constitute those of the multiplier, the adder, the operator, and the accumulator.

Abstract: A full-duplex-type modem employs a decoding device decoding the data which are subjected to convolution-encoding operation and amplitude-phase modulation. That data is subjected to amplitude-phase demodulation at first; and then, it is subjected to viterbi decoding by which an error correction is carried out. In the amplitude-phase demodulation, an amplitude-phase plane is employed and is divided into a plurality of areas in accordance with an arrangement of signal-placing points which is used by the amplitude-phase modulation. When receiving the data, a certain receiving point is defined. Then, one of the areas to which the receiving point belongs is determined; and its area information is produced. A plurality of candidate paths are determined by referring to the signal-placing points which are arranged around the area to which the receiving point belongs.

Abstract: A data transmitter-receiver device transmits a forward data to a communication channel, and receives a backward data with a returning echo noise from the communication channel. The device is provided with a first modulator for modulating the forward data into a first digital signal. A D/A converter converts the modulated first digital signal into a corresponding outgoing analog signal which is transmitted to the communication channel. A delay memory is operated to delay the forward data by a certain time delay corresponding to a return time interval of an echo noise. A second modulator modulates the delayed forward data into a second digital signal. An A/D converter receives an incoming analog signal to convert the same into a corresponding third digital signal. An echo canceler operates based on the first and second digital signals for removing an echo noise from the third digital signal. A demodulator demodulates the third digital signal after removal of the echo noise to produce a backward data.