Unisys Corporation

John L Janssen

Andrew T Jennings

Philip C Bolyn

Michael K Benton

A system and method for automatically detecting the presence and configuration (e.g., number of rows and columns) of a writable memory module. A first data pattern is written to a first memory location. One or more data patterns different from the first data pattern are written to a second and subsequent memory locations in a walking-one sequence. After each write to the second and subsequent memory locations the data pattern at the first memory location is read. The read data pattern is compared to the first data pattern to determine if the first data pattern has been overwritten. The first data pattern is overwritten when the number of memory locations has been exceeded.

Memory controller having automatic RAM detection

A memory system provides a method for error detection and correction. Large data words are divided into multiple error correction zones. One zone from each of two or more words are combined to form an error domain. Address bits are also included in the domains. Check bits are generated from the data bits in each domain and stored with the data. During data retrieval, each domain is processed separately, generating a syndrome for each domain. The syndromes provide indication of bit errors, allowing the correction of a single-bit error in each domain. Multiple-bit errors may thus be corrected within each word using a single-bit error correction code. Data are distributed in physical memory so that, within each domain, no more than one data bit is stored in the same memory device. This method provides full error correction capability in the presence of a catastrophic memory package failure, so long as failures in multiple packages do not cause multiple errors within a single error correction domain. During both read and write operations, error correction code processing may be performed in parallel for multiple domains, enhancing performance.

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Paoli, PA, United States of America

John L Janssen