Accessing coded data stored in a non-volatile memory

• US 8,499,221 B2
• Filed: 07/24/2012
• Issued: 07/30/2013
• Est. Priority Date: 04/30/2009
• Status: Active Grant

• Current Assignee: Globalfoundries US Incorporated (GlobalFoundries, Inc.)
• Original Assignee: International Business Machines Corporation
• Inventors: Franceschini, Michele M., Jagmohan, Ashish, Karidis, John P., Lastras-Montano, Luis A.
• Primary Examiner(s): BRITT, CYNTHIA H
• Application Number:
  US13/556,275
• Publication Number:
  US 20120290898A1
• Time in Patent Office: 371 Days
• Field of Search: 714/718, 714/723, 714/763, 714/767, 714/768, 714/799
• US Class Current: 714/767
• CPC Class Codes: G06F 11/1012 using codes or arrangements adapted for a specific type of error G06F11/1048 takes precedence
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 2212/1036 Life time enhancement
• CPC Class Codes: G06F 2212/401 Compressed data
• CPC Class Codes: G06F 2212/403 Error protection encoding, e.g. using parity or ECC codes
• CPC Class Codes: G06F 2212/7207 management of metadata or control data
• CPC Class Codes: G11C 16/349 Arrangements for evaluating degradation, retention or wearout, e.g. by counting erase cycles

Abstract

Adaptive endurance coding including a method for accessing memory that includes retrieving a codeword from a memory address. The codeword is multiplied by a metadata matrix to recover metadata for the codeword. The metadata includes a data location specification. The data in the codeword is identified in response to the metadata and the data is output as read data.

Claims

1. A method for accessing memory, the method comprising:

retrieving a codeword from a memory address;

multiplying the codeword by a metadata matrix to recover metadata for the codeword, the metadata including a data location specification;

identifying content of read data in the codeword in response to the metadata; and

outputting the read data.

2. The method of claim 1, wherein the codeword further includes ECC bits and the method further comprises applying an ECC decoder to the codeword before performing the multiplying, the ECC decoder designed to implement an ECC code specified by a parity matrix that corresponds to the number of ECC bits in the codeword.

3. The method of claim 2, wherein the number of ECC bits in the codeword is variable.

4. The method of claim 1, wherein the codeword further includes a variable and unknown number of ECC bits and the method further comprises applying one or more ECC decoders to the codeword to locate an ECC decoder that corresponds to the number of ECC bits in the codeword.

5. The method of claim 1, further comprising:

generating the codeword, the generating comprising;

receiving the read data and the metadata; and

placing the read data in the codeword according to the data location specification in the metadata and such that the metadata matrix times the codeword is equal to the metadata; and

writing the codeword to the memory address.

6. A system comprising:

a memory reader retrieving a codeword from a memory address;

a metadata computer multiplying the codeword by a metadata matrix to recover metadata for the codeword, the metadata including a data location specification;

a metadata interpreter identifying content of read data in the codeword in response to the metadata; and

a transmitter outputting the read data.

7. The system of claim 6, wherein the codeword further includes ECC bits and the system further comprises an ECC decoder applying an ECC code to the codeword before performing the multiplying, the ECC code designed to implement an ECC code specified by a parity matrix that corresponds to the number of ECC bits in the codeword.