Memory system for data storage and retrieval

• US 7,917,709 B2
• Filed: 12/15/2009
• Issued: 03/29/2011
• Est. Priority Date: 09/28/2001
• Status: Expired due to Fees

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Lexar Media Incorporated (Micron Technology, Inc.)
• Inventors: Gorobets, Sergey Anatolievich
• Primary Examiner(s): PATEL, HETUL B
• Application Number:
  US12/638,572
• Publication Number:
  US 20100095055A1
• Time in Patent Office: 469 Days
• Field of Search: 711/156, 711/159
• US Class Current: 711/154
• CPC Class Codes: G06F 3/0613 in relation to throughput
• CPC Class Codes: G06F 3/064 Management of blocks
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]

Abstract

According to a first aspect of an embodiment of the invention, there is provided a method of data storage and retrieval for use in a solid state memory system, having a non-volatile memory, wherein data is written to the non-volatile memory in the form of at least one logical sector the method comprising: monitoring the logical sector data which is to be written to the non-volatile memory, detecting the presence of a pattern in the logical sector data, upon detecting a repetitive pattern recording the repetitive pattern of the logical sector in a sector address table in the non-volatile memory without making a record of the logical sector data in the nonvolatile memory.

Claims

1. A method of operating a memory device, the method comprising:

assigning one or more logical sector addresses to one or more physical sector addresses of a non-volatile portion of the memory device and maintaining a sector allocation table comprising the assigned logical sector to physical sector addresses;

receiving a logical sector of data having two or more data portions to be stored in the memory device;

checking the logical sector of data to detect a presence of repetitive data in the logical sector of data prior to writing the logical sector of data to the memory device; and

storing a single portion of the logical sector of data in the sector allocation table without writing any portion of the logical sector of data to a physical sector of the non-volatile portion of the memory device when repetitive data is detected in the logical sector of data.

2. The method of claim 1, further comprising writing the logical sector of data to an assigned physical sector of the non-volatile portion of the memory device when repetitive data is not detected in the logical sector of data.

3. The method of claim 1, wherein storing the single portion of the logical sector of data in the sector allocation table further comprises storing the single portion of the logical sector of data in the sector allocation table where the single portion comprises a single portion of a pattern of the repetitive data detected in the logical sector of data.

4. The method of claim 1, wherein checking the logical sector of data to detect a presence of repetitive data further comprises checking the logical sector of data to detect a presence of repetitive data where repetitive data is detected if each portion of the two or more data portions is equal to each other data portion of the logical sector of data.

5. The method of claim 1, wherein receiving a logical sector of data having two or more data portions further comprises receiving a logical sector of data having two or more data portions where each data portion comprises a byte of data.

6. The method of claim 1, wherein storing a single portion of the logical sector of data in the sector allocation table without writing any portion of the logical sector of data to a physical sector of a non-volatile portion of the memory device further comprises storing the single portion of the logical of data in the sector allocation table and marking the associated logical sector address as erased.

7. The method of claim 6, further comprising performing a read operation in response to a received logical sector read command where the logical sector read command comprises a read command and a logical read address.

8. The method of claim 7, wherein performing a read operation further comprises performing a read operation by accessing a logical address of the sector allocation table comprising the logical read address.

9. The method of claim 8, wherein performing a read operation by accessing a logical address of the sector allocation table comprising the logical read address further comprises retrieving the single portion of data stored along with its associated logical sector address stored in the sector allocation table if the associated logical sector address is marked as erased.

10. The method of claim 1, wherein checking the logical sector of data to detect a presence of repetitive data in the logical sector of data further comprises detecting a presence of repetitive data in the logical sector of data by XOR-ing each of the two or more data portions with each other data portion comprising the two or more data portions to determine the presence of a flat repetitive pattern in the logical sector of data.

11. A method of maintaining a sector allocation table for a memory device where the sector allocation table comprises logical sector address fields and associated physical sector address fields corresponding to physical addresses of a non-volatile portion of the memory device, the method comprising:

receiving one or more logical sectors of data to be stored in the memory device, each logical sector of data having an associated logical sector address;

checking the one or more logical sectors of data to detect the presence of repetitive data in the one or more logical sectors of data prior to storing the one or more logical sectors of data in the non-volatile portion of the memory device; and

storing a portion of the one or more logical sectors of data in the sector allocation table along with an associated logical sector address without storing any portion of the one or more logical sectors of data in associated physical sectors of the memory device when repetitive data is detected.

12. The method of claim 11, further comprising storing each of the one or more logical sectors of data in one or more physical sectors of memory associated with each of the logical sector addresses when repetitive data is not detected.

13. The method of claim 11, wherein storing a portion of the one or more logical sectors of data in the sector allocation table further comprises storing a portion of the one or more logical sectors of data in the sector allocation table where the portion of the one or more logical sectors of data comprises a single portion of a pattern of data comprising the detected repetitive data.

14. A method of maintaining a sector allocation table for a memory device comprising an array of non-volatile memory cells, the method comprising:

receiving a sector of data having an associated logical sector address;

determining if repetitive data is present in the received sector of data prior to storing the sector of data in the array of non-volatile memory cells; and

storing a repeated portion of the sector of data in the sector allocation table along with the associated logical sector address without storing any portion of the sector of data in the array of non-volatile memory cells if repetitive data is determined to be present in the sector of data.

15. The method of claim 14, further comprising programming the received sector of data into a physical address of a location in the array of non-volatile memory cells if repetitive data is not determined to be present in the sector of data, where the physical address of the location in the array of non-volatile memory cells is associated with the logical sector address associated with the received sector of data.

16. The method of claim 14, wherein storing a repeated portion of the sector of data in the sector allocation table along with the associated logical sector address further comprises storing in a volatile memory portion of the memory device.

17. A method of programming a memory device comprising volatile and non-volatile memory portions, the method comprising:

determining when a repetitive pattern of data is present in a sector of data to be stored in the memory device; and

storing a portion of the sector of data in a sector allocation table along with an associated logical sector address without storing any portion of the sector of data in the non-volatile portion of the memory device when a repetitive pattern of data is determined to be present in the sector of data;

wherein the sector allocation table is stored in the volatile memory portion of the memory device.

18. The method of claim 17, further comprising storing the sector of data in a physical address location of the non-volatile memory portion when a repetitive pattern of data is not determined to be present in the sector of data.

19. The method of claim 18, wherein storing a portion of the sector of data in a sector allocation table along with an associated logical sector address further comprises storing a portion of the sector of data in a sector allocation table along with an associated logical sector address and marking the associated logical address as erased.

20. The method of claim 19, further comprising retrieving a sector of data stored in the memory device and associated with a logical address where the sector of data is retrieved from the sector allocation table when the logical address associated with the sector of data to retrieve is marked as erased.

21. The method of claim 19, further comprising retrieving a sector of data stored in the memory device and associated with a logical address where the sector of data is retrieved from a physical address location of the non-volatile memory portion of the memory device, where the physical address location is associated with the logical address which is associated with the sector of data to be retrieved, and where the associated logical address is not marked as erased.

22. A memory device, comprising:

an array of non-volatile memory cells arranged in one or more physical sectors of memory cells;

a controller, wherein the controller is configured to maintain a sector allocation table having a plurality of logical sector address fields and a plurality of corresponding physical sector address fields; and

a pattern detection circuit, wherein the pattern detection circuit is configured to identify a presence of repetitive data in a logical sector of data to be stored in the memory device;

wherein a portion of a logical sector of data identified by the pattern detection circuit to comprise repetitive data is stored in the sector allocation table along with an associated logical sector address without storing any portion of the logical sector of data in a physical sector of memory cells.

23. The memory device of claim 22, wherein a logical sector of data not having been identified by the pattern detection circuit to comprise repetitive data is programmed to a physical sector of non-volatile memory cells associated with a logical sector address associated with the logical sector of data.

24. The memory device of claim 22, wherein the pattern detection circuit comprises XOR logic circuitry.

25. The memory device of claim 22, further comprising a volatile memory device configured to store the sector allocation table.