Patent ID: 6230233
Filing Date: 2001-05-08
Classification: G06F,G11C

Abstract:
A method of managing operation of an EEPROM mass storage system divided into a number of groups of memory cells which are periodically rewritten with new data, wherein individual groups of memory cells have an endurance limit of a maximum number of rewrite cycles to which they can be subjected, comprising:monitoring a number of rewrite cycles directed at individual groups of memory cells and identifying a first of the individual groups of memory cells that has experienced a highest number of rewrite cycles,determining, before any of the individual groups of memory cells reaches its endurance limit, when a predetermined imbalance exists between the number of rewrite cycles experienced by said first of the individual groups of memory cells and a number of rewrite cycles experienced by others of said individual groups of memory cells than said first of the groups of memory cells, andin response to such an imbalance determination, redirecting further rewrite cycles from said first of the individual groups of memory cells to one or more of others of the individual groups of memory cells, thereby tending to reduce the imbalance during further rewrite cycles.