high speed telecommunications systems are disclosed which use a novel line coding scheme for better performance . the line code according to the scheme be can used to produce a block code of arbitrary length . it bounds the minimum number of transitions in a block , and the dc balance of the code . the overhead required is 2 bits if framing is not included and 3 bits if it is . a lookup table is not required to implement the code , thus it remains efficient for longer block lengths . the algorithm required to encode and decode the data can be implemented in serial at the transmission rate or in parallel at the block rate . the coding scheme results in a significant reduction in hardware components of the communication system .