Commodore Electronics Limited

Cagent Technologies, Inc.

Epyx, Inc.

Glenn J Keller

Craig A Nelson

Timothy J McDonald

Robert S Schmid

Javier A Solis

James Redfield

Hedley C Davis

Copy-protected optical disk format, optical disk recording apparatus for creating disks having such formats and optical disk reading apparatus for reading disks having such formats and for determining whether the disks are authentic. In one aspect, an authentic optical disk has data bit indications along a spiral centerline of the disk, and these data bit indications define a radial wobble which has substantially greater energy at a predefined frequency f.sub.CPW (such as f.sub.CC /392) than at a frequency of f.sub.CC /196, where f.sub.CC is the spatial channel clock frequency. In another aspect, an authorized optical disk has data bit indications along a substantially spiral centerline of the disk, according to a channel clock whose frequency varies across the disk. The disk further has stored thereon an indication of the number of such channel clock cycles which occur along a predetermined test segment of the centerline, optionally together with a pointer to the test segment. Since normal data stream copying techniques do not copy the exact channel clock rates on the disk, and since the copying equipment will inherently introduce its own channel clock variations across the resulting disk, the predetermined test segment on the copy will not have the number of channel clocks as that specified by the data indicating the number of channel clock cycles to expect along the test segment.

Optical disk with copy protection, and apparatus and method for

An audio channel system provides an analog signal corresponding to a sound waveform in a computer system. The audio channel system includes a plurality of audio channels. Each audio channel contains a predetermined number of audio data samples for producing a particular sound waveform. A plurality of volume bits define a volume level of each audio data sample to be played. An audio processor processes the sound waveforms of each audio channel. The audio processor acts as a shared processing element which receives the audio data samples from each audio channel. The audio processor divides the audio data samples into a plurality of data such that the plurality of data for each audio data sample is pipelined through the audio processor in a serial manner. The plurality of data for each audio data sample for each audio channel is in various processing stages at any given time. The audio processor combines the data samples and volume bits to produce an audio output signal for each audio channel to produce a total audio output signal.

Audio channel system for providing an analog signal corresponding to a

An apparatus is provided which is responsive to a multiple bit sample of digital information for producing a pulse width modulated signal, the apparatus comprising: a first signal match detector, responsive to a first subset of the multiple bit sample, for producing a first signal that can transition between first and second logical states; a second signal match detector, responsive to a second subset of the multiple bit sample, for producing a second signal that can transition between the first and second logical states; and a voltage summing circuit for producing a first voltage that is substantially proportional to a magnitude of the first signal in one of the first logical state and the second logical state and for producing a second voltage that is substantially proportional to a magnitude of the second signal in one of the first logical state and the second logical state and for producing an output voltage that is substantially proportional to a sum of the first voltage and the second voltage.

Apparatus and method for producing pulse width modulated signals from

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Los Gatos, CA, United States of America

Glenn J Keller