International Business Machines Corporation

Charles H Stapper

John Atkinson Fifield

John Edward Barth, Jr

William Paul Hovis

Howard L Kalter

Scott C Lewis

Kenneth E Beilstein, Jr

Lawrence G Heller

Hsing-San Lee

Daniel J Nickel

Charles E Drake

James A Yankosky

A logic system including a first logic block for providing first differential outputs; a second logic block, identical to the first logic block, for providing second differential outputs; a fault detecting device, coupled to the first logic block, for detecting a fault in the first differential outputs; and a selecting device, coupled to the first and second logic blocks and to the fault detecting device, for selecting an output of one of the first and second logic blocks depending on whether the fault detecting device detects a fault.

Fault tolerant logic system

A DRAM having on-chip ECC and both bit and word redundancy that have been optimized to support the on-chip ECC. The bit line redundancy features a switching network that provides an any-for-any substitution for the bit lines in the associated memory array. The word line redundancy is provided in a separate array section, and has been optimized to maximize signal while reducing soft errors. The array stores data in the form of error correction words (ECWs) on each word line. A first set of data lines (formed in a zig-zag pattern to minimize unequal capacitive loading on the underlying bit lines) are coupled to read out an ECW as well as the redundant bit lines. A second set of data lines receive the ECW as corrected by bit line redundancy, and a third set of data lines receive the ECW as corrected by the word line redundancy. The third set of data lines are coupled to the ECC block, which corrects errors encountered in the ECW. The ECC circuitry is optimized to reduce the access delays introduced by carrying out on-chip error correction. The ECC block provides both the corrected data bits and the check bits to an SRAM. Thus, the check bits can be externally accessed. At the same time, having a set of interrelated bits in the SRAM compensates for whatever access delays are introduced by the ECC. To maximize the efficiency of switching from mode to mode, the modes are set as a function of received address signals.

Dynamic RAM with on-chip ECC and optimized bit and word redundancy

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Jericho, VT, United States of America

Charles H Stapper