Abstract: A system for encoding digital data with an M-ary (d,k) code to provide multi-level coded data where M>2 comprises an M-ary (d,k) encoder for accepting digital input data. The M-ary (d,k) coder encodes the digital input data to produce a plurality of code symbols, where each code symbol is at one of M levels and each pair of non-zero code symbols is separated by at least d but no more than k zeros. A waveform encoder converts the code symbols into waveform signal amplitudes compatible with a multi-level channel. Each waveform signal amplitude is generated by modulo M addition of a current code symbol with a previous waveform signal amplitude. A specific M-ary (d,k) code provides high density recording to a multi-level storage medium. The M-ary (d,k) encoder is implemented using a M-state encoder and a modulo M waveform encoder.

Abstract: A system for encoding digital data with an M-ary (d,k) code to provide multi-level coded data where M>2 comprises an M-ary (d,k) encoder for accepting digital input data. The M-ary (d,k) coder encodes the digital input data to produce a plurality of code symbols, where each code symbol is at one of M levels and each pair of non-zero code symbols is separated by at least d but no more than k zeros. A waveform encoder converts the code symbols into waveform signal amplitudes compatible with a multi-level channel. Each waveform signal amplitude is generated by modulo M addition of a current code symbol with a previous waveform signal amplitude. A specific M=8 (1,2) code provides high density recording to a multi-level storage medium. The M=8 (1,2) encoder is implemented using a four-state encoder and a modulo eight waveform encoder.

Abstract: A system for encoding digital data with an M-ary (d,k) code to provide multi-level coded data where M>2 comprises an M-ary (d,k) encoder for accepting digital input data. The M-ary (d,k) coder encodes the digital input data to produce a plurality of code symbols, where each code symbol is at one of M levels and each pair of non-zero code symbols is separated by at least d but no more than k zeros. A waveform encoder converts the code symbols into waveform signal amplitudes compatible with a multi-level channel. Each waveform signal amplitude is generated by modulo M addition of a current code symbol with a previous waveform signal amplitude. A specific M=8(1,3) code provides high density recording to a multi-level storage medium. The M=8(1,3) encoder is implemented using a two-state encoder and a modulo eight waveform encoder.

Abstract: A system for encoding digital data with an M-ary (d,k) code to provide multi-level coded data where M>2 comprises an M-ary (d,k) encoder for accepting digital input data. The M-ary (d,k) coder encodes the digital input data to produce a plurality of code symbols, where each code symbol is at one of M levels and each pair of non-zero code symbols is separated by at least d but no more than k zeros. A waveform encoder converts the code symbols into waveform signal amplitudes compatible with a multi-level channel. Each waveform signal amplitude is generated by modulo M addition of a current code symbol with a previous waveform signal amplitude. A specific M=7 (3,8) code provides high density recording to a multi-level storage medium. The M=7 (3,8) encoder is implemented using a five-state encoder and a modulo seven waveform encoder.

Abstract: A system for encoding digital data with an M-ary (d,k) code to provide multi-level coded data where M>2 comprises an M-ary (d,k) encoder for accepting digital input data. The M-ary (d,k) coder encodes the digital input data to produce a plurality of code symbols, where each code symbol is at one of M levels and each pair of non-zero code symbols is separated by at least d but no more than k zeros. A waveform encoder converts the code symbols into waveform signal amplitudes compatible with a multi-level channel. Each waveform signal amplitude is generated by modulo M addition of a current code symbol with a previous waveform signal amplitude. A specific M=6 (4,11) code provides high density recording to a multi-level storage medium. The M=6 (4,11) encoder is implemented using a six-state encoder and a modulo six waveform encoder.

Abstract: A system for encoding digital data with an M-ary (d,k) code to provide multi-level coded data where M>2 comprises an M-ary (d,k) encoder for accepting digital input data. The M-ary (d,k) coder encodes the digital input data to produce a plurality of code symbols, where each code symbol is at one of M levels and each pair of non-zero code symbols is separated by at least d but no more than k zeros. A waveform encoder converts the code symbols into waveform signal amplitudes compatible with a multi-level channel. Each waveform signal amplitude is generated by modulo M addition of a current code symbol with a previous waveform signal amplitude. A specific M=4 (1,2) code provides high density recording to a multi-level storage medium. The M=4 (1,2) encoder is implemented using a three-state encoder and a modulo four waveform encoder.

Abstract: A system for encoding digital data with an M-ary (d,k) code to provide multi-level coded data where M>comprises an M-ary (d,k) encoder for accepting digital input data. The M-ary (d,k) coder encodes the digital input data to produce a plurality of code symbols, where each code symbol is at one of M levels and each pair of non-zero code symbols is separated by at least d but no more than k zeros. A waveform encoder converts the code symbols into waveform signal amplitudes compatible with a multi-level channel. Each waveform signal amplitude is generated by modulo M addition of a current code symbol with a previous waveform signal amplitude. A specific M=(3,8) code provides high density recording to a multi-level storage medium. The M=6 (3,8) encoder is implemented using a ten-state encoder and a modulo six waveform encoder.

Abstract: A system for encoding digital data with an M-ary (d,k) code to provide multi-level coded data where M>2 comprises an M-ary (d,k) encoder for accepting digital input data. The M-ary (d,k) coder encodes the digital input data to produce a plurality of code symbols, where each code symbol is at one of M levels and each pair of non-zero code symbols is separated by at least d but no more than k zeros. A waveform encoder converts the code symbols into waveform signal amplitudes compatible with a multi-level channel. Each waveform signal amplitude is generated by modulo M addition of a current code symbol with a previous waveform signal amplitude. A specific M=5 (4,11) code provides high density recording to a multi-level storage medium. The M=5 (4,11) encoder is implemented using a 22-state encoder and a modulo five waveform encoder.

Abstract: A system for encoding digital data with an M-ary (d,k) code to provide multi-level coded data where M>2 comprises an M-ary (d,k) encoder for accepting digital input data. The M-ary (d,k) coder encodes the digital input data to produce a plurality of code symbols, where each code symbol is at one of M levels and each pair of non-zero code symbols is separated by at least d but no more than k zeros. A waveform encoder converts the code symbols into waveform signal amplitudes compatible with a multi-level channel. Each waveform signal amplitude is generated by modulo M addition of a current code symbol with a previous waveform signal amplitude. A specific M=5 (3,7) code provides high density recording to a multi-level storage medium. The M=5 (3,7) encoder is implemented using a six-state encoder and a modulo five waveform encoder.

Abstract: A system got encoding digital data with an M-ary (d,k) code to provide multi-level coded data where M>2 comprises an M-ary (d,k) encoder for accepting digital input data. The M-ary (d,k) coder encodes the digital input data to produce a plurality of code symbols, where each code symbol is at one of M levels and each pair of non-zero code symbols is separated by at least d but no more than k zeros. A waveform encoder converts the code symbols into waveform signal amplitudes compatible with a multi-level channel. Each waveform signal amplitude is generated by modulo M addition of a current code symbol with a previous waveform signal amplitude. A specific M=6 (3,6) code provides high density recording to a multi-level storage medium. The M=6 (3,6) encoder is implemented using a six-state encoder and a modulo six waveform encoder.

Abstract: A system for encoding digital data with an M-ary (d,k) code to provide multi-level coded data where M>2 comprises an M-ary (d,k) encoder for accepting digital input data. The M-ary (d,k) coder encodes the digital input data to produce a plurality of code symbols, where each code symbol is at one of M levels and each pair of non-zero code symbols is separated by at least d but no more than k zeros. A waveform encoder converts the code symbols into waveform signal amplitudes compatible with a multi-level channel. Each waveform signal amplitude is generated by modulo M addition of a current code symbol with a previous waveform signal amplitude. A specific M=7 (1,3) code provides high density recording to a multi-level storage medium. The M=7 (1,3) encoder is implemented using a three-state encoder and a modulo seven waveform encoder.

Abstract: A system for encoding digital data with an M-ary (d,k) code to provide multi-level coded data where M>2 comprises an M-ary (d,k) encoder for accepting digital input data. The M-ary (d,k) coder encodes the digital input data to produce a plurality of code symbols, where each code symbol is at one of M levels and each pair of non-zero code symbols is separated by at least d but no more than k zeros. A waveform encoder converts the code symbols into waveform signal amplitudes compatible with a multi-level channel. Each waveform signal amplitude is generated by modulo M addition of a current code symbol with a previous waveform signal amplitude. A specific M=10 (3,6) code provides high density recording to a multi-level storage medium. The M=10 (3,6) encoder is implemented using a fourteen-state encoder and a modulo ten waveform encoder.

Abstract: A system for encoding digital data with an M-ary (d,k) code to provide multi-level coded data where M>2 comprises an M-ary (d,k) encoder for accepting digital input data. The M-ary (d,k) coder encodes the digital input data to produce a plurality of code symbols, where each code symbol is at one of M levels and each pair of non-zero code symbols is separated by at least d but no more than k zeros. A waveform encoder converts the code symbols into waveform signal amplitudes compatible with a multi-level channel. Each waveform signal amplitude is generated by modulo M addition of a current code symbol with a previous waveform signal amplitude. A specific M=5 (0,2) code provides high density recording to a multi-level storage medium. The M=5 (0,2) encoder is implemented using a three-state encoder and a modulo five waveform encoder.

Abstract: A system for encoding digital data with an M-ary (d,k) code to provide multi-level coded data where M>2 comprises an M-ary (d,k) encoder for accepting digital input data. The M-ary (d,k) coder encodes the digital input data to produce a plurality of code symbols, where each code symbol is at one of M levels and each pair of non-zero code symbols is separated by at least d but no more than k zeros. A waveform encoder converts the code symbols into waveform signal amplitudes compatible with a multi-level channel. Each waveform signal amplitude is generated by modulo M addition of a current code symbol with a previous waveform signal amplitude. A specific M=6 (2,4) code provides high density recording to a multi-level storage medium. The M=6 (2,4) encoder is implemented using a six-state encoder and a modulo six waveform encoder.

Abstract: A system for encoding digital data with an M-ary (d,k) code to provide multi-level coded data where M>2 comprises an M-ary (d,k) encoder for accepting digital input dam. The M-ary (d,k) coder encodes the digital input data to produce a plurality of code symbols, where each code symbol is at one of M levels and each pair of non-zero code symbols is separated by at least d but no more than k zeros. A waveform encoder conveys the code symbols into waveform signal amplitudes compatible with a multi-level channel. Each waveform signal amplitude is generated by modulo M addition of a current code symbol with a previous waveform signal amplitude. A specific M=7 (3,7) code provides high density recording to a multi-level storage medium. The M=7 (3,7) encoder is implemented using a four-state encoder and a modulo seven waveform encoder.

Abstract: A system and method for recording multi-level data to a multi-amplitude recording channel encodes binary data to form multi-level data. The multi-level data are recorded to the storage media for later recall. The system utilizes linear, multi-amplitude recording media which allows data to be stored as multi-level data--requiring fewer `bits` to represent the same number of symbols. To obtain greater data density in the storage media, a diffraction limited write laser is utilized, resulting in a smaller write-spot size. Because the read laser is of a longer wavelength, its diffraction limited spot size is larger. As a result, more than one mark is read at a given read time resulting in a inter-symbol interference. Trellis coded modultation techniques are adopted to convert the binary input data into M-ary data having M levels. Further coding is then performed to compensate for the effects of the inter-symbol interference. This is accomplished by precoding the data using a Tomlinson-Harashima precoder.

Abstract: A light-tight optical disk cartridge is disclosed for use with ETOM erasable and other optical disks in which light baffles incorporating a snap lock feature are utilized in the assembly of the optical disk cartridge in order to provide structural integrity to the cartridge as well as to prevent the entry of light into the cartridge. A snap close slide and latching mechanism is incorporated in order to prevent accidental opening of the access mechanism of the optical disk cartridge.

Abstract: An optical disk structure for an erasable optical disk for use with an erasable optical disk drive using electron trapping optical memory media is disclosed in which several distinct layers in addition to the electron trapping optical memory media are utilized in order to minimize light scatter between adjacent tracks on the disk and to carry permanent format and guidance information for use in acccomplishing the write, read and focusing and traking functions of the erasable optical disk drive with which the disk structures are utilized. The use of absorbing layers as part of the optical disk structure for attenuating reflections of light within the disk structure and eliminating the spreading of marks is also disclosed.

Abstract: An erasable optical disk drive system is disclosed which utilizes an electron trapping media coated on the disk surface to store data in the form of light energy and which utilizes three laser beams, each having a wavelength range distinct from each other as well as distinct from the wavelength range of the emission produced by the impingement of the read laser onto the electron trapping media. Data is written onto the disk, which is contained in a light-tight contamination-free environment, using a visible light laser beam. Data is read from the disk and the disk is erased by using a near infrared light laser beam. The focus and tracking functions of the disk drive system are accomplished by using a laser beam having yet another range of wavelengths, which are greater than those of the visible light laser beam and those of the photon emission from the electron trapping optical memory media, but less than those of the read/erase laser.