Methods of operating a memory system that include outputting a data pattern from a sector allocation table to a host if a logical sector is indicated as being erased

• US 9,032,134 B2
• Filed: 03/12/2012
• Issued: 05/12/2015
• Est. Priority Date: 09/28/2001
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Gorobets, Sergey Anatolievich
• Primary Examiner(s): Chery, Mardochee
• Application Number:
  US13/417,715
• Publication Number:
  US 20120173804A1
• Time in Patent Office: 1,156 Days
• Field of Search: 711/154, 711/103, 711/E12.008, 711/104, 711/105
• US Class Current: 711/103
• 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

A method of operating a memory system includes receiving a read command from a host, where the read command is associated with a logical sector of a memory, determining whether the logical sector of the memory is indicated as being erased in a sector allocation table, if the logical sector of the memory is indicated as being erased, outputting a data pattern from the sector allocation table to the host, and if the logical sector of the memory is not indicated as being erased, reading a physical sector of the memory and outputting data from the physical sector of the memory to the host.

Claims

1. A method of operating a memory system, comprising:

receiving a read command from a host, wherein the read command is associated with a logical sector of a memory;

determining whether the logical sector of the memory is indicated as being erased in a sector allocation table; and

when the logical sector of the memory is indicated as being erased, generating a sector of data from a data pattern in the sector allocation table and outputting the generated sector of data to the host;

wherein the generated sector of data is an original sector of data intended to be written to the logical sector of the memory in response to a write command and the data pattern is a portion of the original sector of data.

2. The method of claim 1, wherein outputting the generated sector of data to the host when the logical sector of the memory is indicated as being erased comprises outputting the generated sector of data regardless of whether a physical sector of the memory corresponding to the logical sector of the memory is actually erased.

3. The method of claim 1, wherein outputting the generated sector of data to the host comprises outputting the generated sector of data from a pattern output circuit, wherein the generated sector of data is generated from the data pattern using the pattern output circuit.

4. The method of claim 1, wherein the data pattern comprises a data pattern of 1, 2 or 4 bytes.

5. The method of claim 4, wherein the generated sector of data is generated from the data pattern by repeating the data pattern of 1, 2 or 4 bytes for the generated sector of data.

6. The method of claim 1, wherein determining whether the logical sector of the memory is indicated as being erased in a sector allocation table comprises determining whether the logical sector of the memory is indicated as having an invalid mapping to a particular reserved location of the memory and determining that a memory sector offset component of the sector allocation table contains all 1s.

7. The method of claim 1, wherein determining whether the logical sector of the memory is indicated as being erased in a sector allocation table comprises determining whether the logical sector of the memory is indicated as having a mapping to a valid data block of the memory and determining that a particular bit of a memory sector offset component of the sector allocation table has a particular value.

9. The method of claim 7, wherein outputting the generated sector of data to the host comprises outputting the generated sector of data from a pattern output circuit that generates the generated sector of data from the data pattern.

10. The method of claim 9, wherein the pattern output circuit generates the generated sector of data from the data pattern by repeating the data pattern.

11. The method of claim 9, wherein the generated sector of data generated by the pattern output circuit from the data pattern comprises all 1s.

8. A method of operating a memory system, comprising:

receiving a read command from a host, wherein the read command is associated with a logical sector of a memory;

determining whether the logical sector of the memory is indicated as being erased, or having an invalid mapping to a reserved location of the memory, in a sector allocation table;

when the logical sector of the memory is indicated as being erased, or having an invalid mapping to a particular reserved location of the memory, generating a sector of data from a data pattern in the sector allocation table and outputting the generated sector of data to the host;

wherein the generated sector of data is an original sector of data intended to be written to the logical sector of the memory during a write operation and the data pattern is a portion of the original sector of data, wherein the data pattern was recorded in the sector allocation table instead of writing the original sector of data in the logical sector of the memory during the write operation; and

when the logical sector of the memory is indicated as having an invalid mapping to a reserved location of the memory different than the particular reserved location of the memory, returning an error status to the host.

12. The method of claim 8, wherein determining whether the logical sector of the memory is indicated as having an invalid mapping to a reserved location of the memory comprises determining whether the logical sector of the memory is indicated as having a mapping to one of a plurality of special control blocks that can never map onto valid data sectors.

13. A method of operating a memory system, comprising:

receiving a read command from a host, wherein the read command is associated with a logical sector of a memory;

determining whether the logical sector of the memory is indicated as being erased, or having an invalid mapping to a reserved location of the memory, in a sector allocation table;

when the logical sector of the memory is indicated as being erased, or having an invalid mapping to a particular reserved location of the memory, programming a pattern output circuit with a data pattern from the sector allocation circuit, generating a sector of data from the data pattern using the pattern output circuit, and outputting the generated sector of data from the pattern output circuit to the host, wherein the generated sector of data is an original sector of data intended to be written to the logical sector of the memory in response to a write command and the data pattern is a portion of the original sector of data; and

when the logical sector of the memory is indicated as having an invalid mapping to another reserved location of the memory different than the particular reserved location of the memory, returning an error status to the host.

14. The method of claim 13, further comprising reading the data pattern from the sector allocation table.

15. The method of claim 14, wherein reading the data pattern from the sector allocation table comprises reading the data pattern from a memory sector offset component of the sector allocation table.

16. The method of claim 13, wherein outputting the generated sector of data from the pattern output circuit to the host comprises outputting the generated sector of data from the pattern output circuit to the host regardless of whether a physical sector of the memory corresponding to the logical sector of the memory is actually erased.

17. The method of claim 13, wherein the data pattern is a data pattern of all 1s.

18. The method of claim 13, wherein generating the sector of data from the data pattern using the pattern output circuit comprises repeating the data pattern.

19. The method of claim 13, wherein determining whether the logical sector of the memory is indicated as having an invalid mapping to a reserved location of the memory comprises determining whether the logical sector of the memory is indicated as having a mapping to one of a plurality of special control blocks that are not permitted to map onto valid data sectors.

20. The method of claim 13, wherein determining whether the logical sector of the memory is indicated as being erased comprises determining whether the logical sector of the memory is indicated as having an invalid mapping to the particular reserved location of the memory and determining that a memory sector offset component of the sector allocation table contains all 1s.