The Serial ATA encoding scheme relies on the well-known 8b/10b encoding scheme that is used in several other successful high-speed serial communications schemes. The encoding scheme has many well known benefits, including limited run length, DC balance, and the ability to encode special control characters known as primitives. These benefits far outweigh the 20-percent encoding overhead it carries. One challenge designers face in implementing 8b/10b encoding or decoding circuits is in efficient and timely encoding or decoding of characters with running disparity tracking. Additionally, because the decoding scheme could result in bit errors propagating in a way that produces a cascade of errors. This article explores the encoding scheme in moderate detail and the possible pit falls associated with encoding and decoding, as well as possible solutions.