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Address Block Scrambler for Nonvolatile Memories

IP.com Disclosure Number: IPCOM000080443D
Original Publication Date: 1973-Dec-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Harroun, TV: AUTHOR

Abstract

This method circumvents the local failure of variable-threshold memory devices due to fatigue problems, by providing a system organization which uniformly distributes storage activity throughout the real physical address space.

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Address Block Scrambler for Nonvolatile Memories

This method circumvents the local failure of variable-threshold memory devices due to fatigue problems, by providing a system organization which uniformly distributes storage activity throughout the real physical address space.

One of the problems encountered in read/write applications of nonvolatile MXOS (metal-x-oxide semiconductor) devices is fatigue. Fatigue manifests itself by a disappearance of the threshold "window" after a finite number of write cycles, resulting in failure of the device as a storage element.

In storage applications where memory activity tends to cluster in a particular physical address space, the memory may fail in some local physical area due to fatigue. File applications which have demonstrated the 80-20 rule, i.e., 80 percent of the storage activity is confined to 20 percent of the logical address space, are particularly subject to fatigue failures.

A solution which circumvents local fatigue failure is to provide logic and a directory, so that physical storage operations can be uniformly distributed over the entire physical address space of the memory or file.

Basically, the storage system is divided into blocks and the write operation of each block counted. In this way, high-activity blocks are detected and by suitable logic, the block address is dynamically modified in the memory so that subsequent system accesses to that logical address are directed to a different low activity, physi...