International Business Machines Corporation

Albert X Widmer

Peter Anthony Franaszek

Alain R Blanc

Daniel Michael Kuchta

John Farley Ewen

Dennis L Rogers

Benjamin D Parker

Bernard Brezzo

Charles Louis Haymes

Carl J Anderson

Pierre Debord

Kevin R Wrenner

A technique for encoding 9-binary symbol (9B) source vectors into 10-binary symbol (10B) encoded vectors include the steps of obtaining a plurality of 9B source vectors, and encoding the 9B source vectors into a plurality of 10B encoded vectors according to an encoding scheme. A fraction of the 10B encoded data vectors have binary symbol changes, other than whole-vector complementation, compared to corresponding ones of the 9B source vectors, the fraction not including any disparity dependent encoded representations. Techniques for encoding 7B source vectors to 8B encoded vectors, and decoding techniques, are also provided.

Techniques for 9B10B and 7B8B coding and decoding

Techniques for encoding N-binary symbol (NB) source data vectors into M-binary symbol (MB) encoded vectors, M&#x3e;N&#x3e;0, are provided. Techniques for decoding are also provided. Exemplary coding and decoding apparatuses are presented, as is an exemplary 8B/10B encoding scheme. Encoded vectors may be disparity dependent or disparity independent. In assigning encoded vectors that have one or more individual binary symbol changes compared with their source data vectors, preference can be given to encoded vectors that are balanced and disparity independent. Whole-vector complementation and individual changes of one or more binary symbols can advantageously be performed substantially in parallel.

NB/MB coding apparatus and method using both disparity independent and disparity dependent encoded vectors

During decoding and encoding, the starting disparity of a current block is computed by using a disparity at some previous reference point and disparity characteristics of bytes from the reference point to a current block boundary. The characteristics of the bytes are whether the bytes are unbalanced coded vectors and whether the number of unbalanced vectors is even or odd. Alternately, the characteristics of the bytes are whether the bytes are balanced and how many balanced coded vectors exist. New classifications are created for encoding and decoding 3B/4B and 5B/6B transmission codes. Separate functions are created that address specifically disparity aspects. A dispartiy violation at the front of a byte is detected during decoding by comparing a required front-end disparity of the byte with the actual running disparity by assuming the actual running disparity is equivalent to an exit disparity of the next preceding byte that is disparity dependent.

8B/10B encoding and decoding for high speed applications

Correction and location information are determined from a number of data vectors. The location information comprises values determined from subsets of the data vectors. Two or more of the subsets have one or more data vectors in common, but also have one or more data vectors, in one or more of the subsets, that are not in other subsets. The subsets comprise groups of data vectors, and the groups of data vectors have a size that is a function of a power of two. Transmission codes are used on the data vectors and correction and location information. Received location information and determined location information are compared to determine a data vector having an error. Received correction information and determined correction information are compared to correct the data vector having the error. Failing optical lanes may be replaced efficiently by using a number of multiplexers coupled to electrical lanes and optical lanes.

Error correction with low latency for bus structures

Techniques are disclosed for translating five-bit source vectors into six-bit coded vectors. A sixth bit having a default value is appended to the source vectors. Selected one to three individual source bits are complemented for a minority of the plurality of source vectors. The coded vectors are either disparity independent with a single representation or disparity dependent with a primary and an alternate representation, where the alternate representation is a complement of the primary representation. Additional techniques are disclosed for translating three-bit source vectors together with one or more control inputs, into nine four-bit coded vectors. A fourth bit having a default value is appended to the source vectors. A single individual bit is complemented for a minority of source vectors. The coded vectors are either disparity independent with a single representation or disparity dependent with a primary and an alternate representation, where the alternate representation is a complement of the primary representation. 8B/10B and 10B/12B encoding techniques are also disclosed.

5B/6B-T, 3B/4B-T and partitioned 8B/10B-T and 10B/12B transmission codes, and their implementation for high operating rates

A transmission code which packs six bits of data and four control vectors into an eight-hit format is presented. A direct current (DC)-balanced 6B/8B transmission code is produced from an input data stream that includes one or more six-bit source vectors. A given coded vector is created in accordance with an eight binary digit coded vector set. The given coded vector has eight binary digits and the given coded vector corresponds to a given six-bit source vector. Each coded vector in the eight binary digit coded vector set is balanced. The given coded vector is output.

DC-balanced 6B/8B transmission code with local parity

The present invention provides techniques for classifying disparities and source vectors for 7B/8B and 9B/10B transmission codes, which are then used to minimize the complexity of decoding and encoding for 16B/18B codes. The classifications are determined for source vectors and for disparity for coded vectors. The vector classifications are selected in a predetermined manner so that the number of classifications is minimized for bit mapping, disparity control, or both. Additionally, the number of bits changed for bit mapping is minimized. Decoding of 7B/8B and 9B/10B transmission codes is performed by converting coded vectors into a single image and then performing decoding operations to decode the single image of the coded vectors. The single image is a primary coded vector, and an alternate coded vector is an inverted version of the primary coded vector. Techniques are presented for using 5B/6B, 7B/8B and 9B/10B transmission codes in other transmission codes such as 12B/14B and 17B/20B transmission codes. A 17B/20B may be created by using two parallel 9B/10B decoders or by using one 7B/8B encoder and two 5B/6B encoders.

DC balanced 7B/8B, 9B/10B, and partitioned DC balanced 12B/14B, 17B/20B, and 16B/18B transmission codes

A diagnostic system utilizes a monitor photodiode and a laser from a fiber optic data link transceiver to perform diagnostic measurements on the fiber optic data link. The diagnostic system includes a multiplexer connected between the encoder and the laser driver of the fiber optic data link. The multiplexer is controlled by a normal op/test mode selector and receives a pulse or pattern for the test mode from a pulse/pattern generator. A signal from the monitor photodiode flows into a pulse/pattern detection circuit which signals a register if a pattern is found. After a reflected pulse is detected, the register captures a count and forwards it to a service processor or system to be analyzed.

Fiber optic data link module with built-in link diagnostics

A method of coding parallel data for transmission while maintaining baud rate includes the steps of providing a plurality of uncoded data blocks having a predetermined baud rate, demultiplexing the data blocks to sequentially distribute the data blocks to encoders, encoding the data blocks at the predetermined baud rate, and serializing the coded data blocks for serially transmitting data at the predetermined baud rate. A system for coding parallel data for serial transmission while maintaining baud rate is included wherein the predetermined baud rate is maintained by providing an adequate number transmission links rather than increasing baud rate.

Transformation of parallel interface into coded format with preservation of baud-rate

A flow control process for a switching architecture having a central switch core with associated distributed Switch Core Access Layers communicating with the core by means of serial data communication links. The serial links carry data flows that are coded in accordance with the 8B/10B coding, where two among the three comma characters are used for creating an additional specialized flow control channel. When the cells are idle or empty, the nature of the comma character that appears at the beginning of the cell provides the appropriate flow control bit information. For instance, should the K.28.5 character be detected, the receiving entity (either the switching structure or a distributed SCAL element) decodes the character as positive flow control information, corresponding to a request to reduce the incoming data flow. Also, should the K.28.1 character be decoded, then the receiving entity decodes this as information according to which no reduction in the data flow is requested. When the incoming flow provides data cells, the invention uses a predetermined bit within the data cell, generally that immediately following the beginning of the cell, in order to carry the flow control information.

Flow control process for a switching architecture using an out-of-band flow control channel and apparatus for performing the same

A format converter in which the data input is a 16 bit wide interface. The circuit finds the 66-bit coding block boundaries. In one embodiment, a circuit presents the 66-bit data blocks at the output in an aligned format. The circuit relies on control inputs from a state machine which controls the operating mode and to which it delivers status information. The two main operating modes are the &ldquo;normal data&rdquo; mode or the &ldquo;hunt&rdquo; mode for the 66-bit block boundaries.

Format converter

A coding system includes methods and apparatus for producing a (0,6) run length limited rate 16B/18B code. The code produced is dc balanced and capable of operating near the theoretical performance limits for a 16B/18B code. This means the code is near optimum for run length and digital sum variation for a 16B/18B code. In one aspect of the invention, each 16-bit input data stream or block is broken into a 9-bit and a 7-bit sub-block and encoded separately while maintaining both dc balance and run length constraints across all block and sub-block boundaries. The present invention also provides a plurality of special purpose control characters such as commas, delimiters, idle characters, etc., by using the extra bits in the coded blocks whereby the special characters may be readily distinguished from data, while at the same time maintaining the dc balance and run length limitations in such characters. The 16B/18B transmission coding system of the invention also provides error correction techniques.

Partitioned DC balanced (0,6) 16B/18B transmission code with error correction

The present invention is directed to a method for determining whether a current word in a stream of words having a plurality of frames is an idle word, an end-of-frame word, a start-of-frame word of one of the plurality of frames of words wherein an error can occur in the stream of words. The current word contains four bytes. One of the plurality of frames of words starts with a start-of-frame word and ends with an end-of-frame word. One of the plurality of frames of words is followed by a modified idle word. Between each of the plurality of frames of words there is at least one idle word. Each of the end-of-frame word, the start-of-frame word, the modified-idle word and the idle word has four bytes. The method contains the following steps: determining if the current word is an idle word. The current word is assumed to be an idle word if three of the four bytes of the current word match three of the four bytes of the idle word and if it is followed by the start-of-frame words. If the current word is not an idle word, determining if the current word is a start-of-frame words. If the current word is not an idle word, determining if the current word is a start-of-frame word. The current word is assumed to be a start-of-frame word if three of the four bytes of the current word match three of the bytes of the start-of-frame word and if a word preceding the current word is an idle word. If the current word is not a start-of-frame word, determining if the current word is an end-of-frame word. The current word is assumed to be an end-of-frame word if either all of the four bytes of the current word match the four bytes of the end-of-frame word and at least one byte of a next word following the current word match the four bytes of the modified-idle word, or if at least three of the four bytes of the current word match the four bytes of the end-of-frame word and at least two bytes of the next word matches two bytes of the modified idle word.

Method for detecting start-of-frame, end of frame and idle words in a

The present invention is directed to a method and apparatus to correct errors in bits of binary coded data transmitted from a first electronic device to a second electronic device by providing a frame of bits which contains a plurality of transmission code constrained bytes of bits; determining a first parity for the bytes of the frame; determining a balance for each of the plurality of code constrained bytes; grouping the bytes into words, wherein each word has a balance formed from the balance of each of the bytes in the word, determining a second parity from the group and word balances; transmitting the frame, the first parity and the second parity of the frame to the second electronic device; the second electronic device redetermines from the transmitted frame a redetermined first parity and a redetermined second parity; the second electronic device compares the transmitted first parity to the redetermined first parity to determine a bit location of an error in said bytes; the second electronic device compares the transmitted second parity to the redetermined second parity to determined which of the bytes contain the error; and changing the bit location in the byte containing said error. The second electronic device determines whether there is a code violation and limits the search of the second parity to a series of bytes ending with the byte indicating a code violation. Included is also technique to reliably detect Start of Frame and End of Frame.

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Katonah, NY, United States of America

Albert X Widmer