Browse Prior Art Database

RUN-LENGTH LIMITED CODES

IP.com Disclosure Number: IPCOM000024546D
Original Publication Date: 1980-Dec-31
Included in the Prior Art Database: 2004-Apr-02
Document File: 2 page(s) / 147K

Publishing Venue

Xerox Disclosure Journal

Abstract

When digital data is recorded on magnetic media, transistions are written or not written at regular, discreet intervals along the media in accordance with a code or rule. Such transitions and lack of transitions are termed "encoded data ones and zeros" or merely "ones" and "zeros", respectively.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 61% of the total text.

RUN-LENGTH LIMITED CODES Kermit A. Norris

Proposed Classification U.S. Cl. 360/39 Int. Cl. GlIb 5/09

When digital data is recorded on magnetic media, transistions are written or not written at regular, discreet intervals along the media in accordance with a code or rule. Such transitions and lack of transitions are termed "encoded data ones and zeros" or merely "ones" and "zeros", respectively.

The statistical properties of the sequence of encoded "ones" and "zeros" are determined by the code used and are typically a significant factor in the major design parameters of a storage system. Following conventional nomenclature, the important statistical or generic characteristics of a code are given by five parameters; d, k, m, n, r. The "d" and "k" parameters are concatenation restraints signifying respectfully the minimum and maximum number of "zeros" that can separate each "one". A code with "d" and "k" restraints is said to be "run-length limited". Furthermore, the encoded sequence is synchronous with the data sequence, and the parameters m, n and r signify that r·m data bits relate to r·n encoded bits when r is any integer between one and r. Since the greatest density limitation on magnetic media is the crowding of "ones", a high "d" is desirable. As the recovered sequence must be self-clocking from "ones" timing, a low "k" is desired. A high m/n ratio a lso yields less crowding and a lower r generally indicates simpler electronics.

The 2, 7, 1, 2, 3 code, which follows...