Sequence-state methods for run-length-limited coding

IBM Journal of Research and Development, Volume 14, Issue 4, pp. 376-383 (1970).

Constrained coding is a process that transforms a variety of code strings so that they require less storage space or require less transmission time when sent over a communications link. This process is widely used in digital recording and communications systems.

This 1970 Journal paper is an early paper in a series published by Peter Franaszek on the theory and application of constrained channel coding. Franaszek's research in this area was honored by the prestigious ACM Paris Kanellakis Theory and Practice Award and the IEEE Emanuel R. Piore Award. ACM praised Franaszek for his work on the “encoding of digital data for transmission and storage [that] has led to revolutionary advances in the recording density of digital media as well as the transmission bandwidth of digital communications systems.” These codes enforce constraints on the sequence of signals in order to limit interference, enable clock synchronization, and shape the signal spectrum.

Franaszek's theoretical work is at the core of several codes currently incorporated in common industry standards. His contributions range from fundamental theory to detailed implementations. Note that Franaszek developed the first sliding-block run-length-limited (RLL) code, used in a variety of magnetic and optical recording standards. His further collaborative research with IBM researcher Albert Widmer led to the 8B/10B code, widely used in storage and interconnection networks, and included in standards such as Fibre Channel and Gigabit Ethernet. This code and its accompanying protocol define high-speed data transfer interfaces that can be used to connect workstations, mainframes, supercomputers, storage devices, and displays. The code is incorporated in the IBM Enterprise Systems Connection (ESCON^®) Architecture^®, and it is also used by British Telecom and Optica Technologies Incorporated. As part of the Hitachi channel extender, the concepts increase the maximum communication distances between mainframe computers or between mainframes and peripherals, such as workstations, printers, and storage devices.

Related papers:	Construction of bounded delay codes for discrete noiseless channels (JRD 1982) by P. A. Franaszek A DC-balanced, partitioned-block, 8B/10B transmission code (JRD 1983) by A. X. Widmer and P. A. Franaszek
See Peter Franaszek's ACM Paris Kanellakis Theory and Practice Award (2002) and IEEE Emanuel R. Piore Award (1989).