International Business Machines Corporation

Robert M Blake

John Atkinson Fifield

Howard L Kalter

Chin-Long Chen

Douglas Craig Bossen

William Paul Hovis

Tin-Chee Lo

David J Perlman

In a memory system comprising a plurality of memory units each of which possesses unit-level error correction capabilities and each of which is tied to a system level error correction function, memory reliability is enhanced by providing a mechanism for disabling the unit-level error correction capability, for example, in response to the occurrence of an uncorrectable error in one of the memory units. This counter-intuitive approach which disables an error correction function nonetheless enhances overall memory system reliability since it enables the employment of the complement/recomplement algorithm which depends upon the presence of reproducible errors for proper operation. Thus, chip level error correction systems, which are increasingly desirable at high packaging densities, are employed in a way which does not interfere with system level error correction methods.

Fault tolerant computer memory systems and components employing dual

In a memory system comprising a plurality of memory units each of which possesses unit-level error correction capabilities and each of which are tied to a system level error correction function, memory reliability is enhanced by providing means for disabling the unit-level error correction capability, for example, in response to the occurrence of an uncorrectable error in one of the memory units. This counter-intuitive approach which disables an error correction function nonetheless enhances overall memory system reliability since it enables the employment of the complement/recomplement algorithm which depends upon the presence of reproducible errors for proper operation. Thus, chip level error correction systems, which are increasingly desirable at high packaging densities, are employed in a way which does not interfere with system level error correction methods.

In a memory system, which includes a dynamic random access memory (DRAM) that has to be precharged before the contents thereof can be selectively read out into a static register, there is provided means for reading the memory contents of the memory cells of a part or the whole of a row of memory cells of the DRAM into the static register while concurrently precharging the DRAM for a subsequent read-out command. This reduces the overall cycle time of the memory array since read-out of the static register can occur during precharge.

Early row address strobe (RAS) precharge

In a memory system comprising a plurality of memory units each of which possesses unit-level error correction capabilities and each of which are tied to a system level error correction function, memory reliability is enhanced by providing a mechanism for disabling the unit-level error correction capability, for example, in response to the occurrence of an uncorrectable error in one of the memory units. This counter-intuitive approach which disables an error correction function nonetheless enhances overall memory system reliability since it enables the employment of the complement/recomplement algorithm which depends upon the presence of reproducible errors for proper operation. Thus, chip level error correction systems, which are increasingly desirable at high packaging densities, are employed in a way which does not interfere with system level error correction methods.

In a memory system comprising a plurality of memory units each of which possesses unit-level error correction capabilities and each of which are tied to a system level error correction function, memory reliability is enhanced by providing means for fixing the output of one of the memory units at a fixed value in response to the occurrence of an uncorrectable error in one of the memory units. This counter-intuitive approach to the generation of forced hard errors nonetheless enhances overall memory system reliability since it enables the employment of the complement/recomplement algorithm which depends upon the presence of reproducible errors for proper operation. Thus, clip level error correction systems, which are increasingly desirable at high packaging densities, are employed in a way which does not interfere with system level error correction methods.

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Wappingers Falls, NY, United States of America

Robert M Blake