Codes for Write-Once Memories

摘要

Storage media which consist of a number of write-once bit positions (wits) are considered. A wit initially contains a 0 that may be irreversibly overwritten with a 1. Such a storage medium is called a write-once memory or wom. Examples are punched cards or digital optical disks. With coding, it is possible to use a wom several times, up to a very high rate. An infinite class of wom codes is described. In this class, messages are identified with cosets of linear error-correcting codes. This construction is partially analyzed for binary Hamming codes using finite geometries. Results of simulations of the Hamming wom codes are given, and extensions are described. The Golay wom code is analyzed. Examples indicate connections between wom codes and error detecting codes and memory-protecting.