Abstract: A system for encoding consecutive parallel bytes of source data into an RLL (1,7) output symbol string and decoding an input RLL (1,7) symbol string to produce an output sequence of parallel bytes of data. The system accepts an input sequence of parallel data bytes occurring at a byte rate and provides, in response, the output RLL symbol string at a symbol string rate which is twelve times the byte rate. Similarly, the output byte sequence has a byte rate which is 1/12 of the input RLL symbol string rate. The system performs RLL encoding and decoding at the byte rate, thus eliminating the odd 2/3 f.sub.C source clock required in systems performing RLL coding and decoding functions on a bit-by-bit basis.

Abstract: An apparatus for producing, from four consecutive unconstrained data bits in a bit string, a run-length-limited (RLL) encoded symbol consisting of three coded data bits. The internal state of the encoder is described by one state bit. The encoder performs RLL (1,7) encoding on a bit-by-bit basis, and can be cascaded in parallel to perform encoding on sequential, equally-sized groups of unencoded data bits. An attractive feature of the encoder is that it can be cascaded to simultaneously encode consecutive bytes of data.