6b/8b Encoding

6b/8b Encoding

In telecommunications, 6b/8b is a line code that expands 6-bit codes to 8-bit symbols for the purposes of maintaining DC-balance in a communications system.

Each 8-bit output symbol contains 4 zero bits and 4 one bits, so the code can, like a parity bit, detect all single-bit errors.

The number of binomial coefficient 8-bit patterns with 4 bits set is = 70. Further excluding the patterns 11110000 and 00001111, this allows 68 coded patterns: 64 data codes, plus 4 additional control codes.