Cray Incorporated

Michael Higgins

Van L Snyder

David R Resnick

Gerald A Schwoerer

Dennis Charles Abts

Kelly J Marquardt

Alan M Grossmeier

Roger A Bethard

Michael L Steinberger

R Paul Dixon

Various embodiments include fault tolerant memory apparatus, methods, and systems, including a memory manager for supplying read and write requests to a memory device having a plurality of addressable memory locations. The memory manager includes a plurality of banks. Each bank includes a bank queue for storing read and write requests. The memory manager also includes a request arbiter connected to the plurality of banks. The request arbiter removes read and write requests from the bank queues for presentation to the memory device. The request arbiter includes a read phase of operation and a write phase of operation, wherein the request arbiter preferentially selects read requests for servicing during the read phase of operation and preferentially selects write requests for servicing during the write phase of operation.

Systems and methods for read/write phase request servicing

A memory controller and method that provide a read-refresh (also called 'distributed-refresh') mode of operation, in which every row of memory is read within the refresh-rate requirements of the memory parts, with data from different columns within the rows being read on subsequent read-refresh cycles until all rows for each and every column address have been read, scrubbing errors if found, thus providing a scrubbing function that is integrated into the read-refresh operation, rather than being an independent operation. For scrubbing, an atomic read-correct-write operation is scheduled. A variable-priority, variable-timing refresh interval is described. An integrated card self-tester and/or card reciprocal-tester is described. A memory bit-swapping-within-address-range circuit, and a method and apparatus for bit swapping on the fly and testing are described.

Method and apparatus for memory read-refresh, scrubbing and variable-rate refresh

Various embodiments include fault tolerant memory apparatus, methods, and systems, including an apparatus comprising a memory device including a plurality of addressable memory locations, and a memory manager coupled to the memory device, the memory manager including a scheduling unit operable to detect a multi-bit error in data read from the memory device, and to retry the read operation in order to distinguish between an intermittent error and a persistent error.

Multi-bit memory error management

Apparatus and method for memory read-refresh, scrubbing and variable-rate refresh

Apparatus and method for memory asynchronous atomic read-correct-write operation

Apparatus and method for memory with bit swapping on the fly and testing

Growing community of inventors

Eau Claire, WI, United States of America

Michael Higgins