Memory devices and methods for use therewith

• US 6,738,883 B2
• Filed: 09/23/2002
• Issued: 05/18/2004
• Est. Priority Date: 09/15/2000
• Status: Expired due to Term

• Current Assignee: SanDisk Technologies LLC (Western Digital Corporation)
• Original Assignee: Matrix Semiconductor, Inc. (Western Digital Corporation)
• Inventors: Moore, Christopher S., Brown, Daniel T., March, Roger W.
• Primary Examiner(s): PORTKA, GARY J
• Application Number:
  US10/253,049
• Publication Number:
  US 20030023828A1
• Time in Patent Office: 603 Days
• Field of Search: 707/100, 707/101, 707/102, 707/205, 711/101, 711/102, 711/103, 711/170, 711/171, 711/172, 711/173
• US Class Current: 711/171
• CPC Class Codes: G06F 11/1008 in individual solid state devices G06F11/1004 takes precedence
• CPC Class Codes: G06F 2003/0697 device management, e.g. handlers, drivers, I/O schedulers
• CPC Class Codes: G06F 3/0601 Interfaces specially adapted for storage systems
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0631 by allocating resources to storage systems
• CPC Class Codes: G06F 3/0643 Management of files
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]
• CPC Class Codes: G06F 3/08 from or to individual record carriers, e.g. punched card , memory card, integrated circuit [IC] card or smart card
• CPC Class Codes: G11C 17/00 Read-only memories programmable only once; Semi-permanent stores, e.g. manually-replaceable information cards
• CPC Class Codes: Y10S 707/99934 Query formulation, input preparation, or translation
• CPC Class Codes: Y10S 707/99943 Generating database or data structure, e.g. via user interface
• CPC Class Codes: Y10S 707/99953 Recoverability
• CPC Class Codes: Y10S 707/99956 File allocation

Abstract

The preferred embodiments described herein provide a memory device and methods for use therewith. In one preferred embodiment, a method is presented for using a file system to dynamically respond to variability in an indicated minimum number of memory cells of first and second write-once memory devices. In another preferred embodiment, a method for overwriting data in a memory device is described in which an error code is disregarded after a destructive pattern is written. In yet another preferred embodiment, a method is presented in which, after a block of memory has been allocated for a file to be stored in a memory device, available lines in that block are determined. Another preferred embodiment relates to reserving at least one memory cell in a memory device for file structures or file system structures. A memory device is also provided in which file system structures of at least two file systems are stored in the same memory partition. Additionally, methods for permanently preventing modification of data stored in a memory device and for identifying memory cells storing data are disclosed.

Claims

1. A method for storing a file in a contiguous set of memory cells in a memory device, the method comprising:

(a) reserving at least one memory cell in a contiguous set of memory cells for a file structure of a file to be stored in the contiguous set of memory cells;

(b) storing the file in the contiguous set of memory cells, wherein the file is stored only in unreserved memory cells; and

(c) if there are enough unreserved memory cells in the continuous set of memory cells to store the file structure;

(c1) storing the file structure in the unreserved memory cells; and

(c2) storing a second file in the at least one memory cell reserved for the file

(d) if there are not enough unreserved memory cells in the contiguous set of memory cells to store the file structure, storing the file structure in the reserved at least one memory cell.

2. The method of claim 1 further comprising, before the act of reserving, determining a number of memory cells needed to store the file structure.

3. The method of claim 1, wherein the file structure comprises a file structure selected from the group consisting of a file footer, a file name, a file attribute, and a file descriptor.

4. The method of claim 1, wherein the reserved at least one memory cell is at an end of the contiguous set of memory cells.

5. The method of claim 1, wherein the memory device is logically organized into a plurality of blocks, each block comprising a plurality of lines;

and wherein the reserved at least one memory cell comprises a line.

6. The method of claim 5, wherein a line comprises a minimum number of memory cells that can be written into during a write operation.

7. The method of claim 1, wherein the memory device is logically organized into a plurality of blocks, each block comprising at least one line;

and wherein the reserved at least one memory cell comprises a block.

8. The method of claim 7, wherein a line comprises a minimum number of memory cells that can be written into during a write operation.

9. The method of claim 1, wherein the memory device comprises a write-once memory device.

10. The method of claim 1, wherein the memory device comprises a three-dimensional write-once memory device.

11. A method for partitioning memory cells in a write-once memory device comprising a plurality of memory cells, the method comprising:

(a) creating a partition of memory cells in a write-once memory device;

(b) reserving at least one memory cell in the partition for a file system structure of the partition;

(c) storing a file in the partition, wherein the file is stored only in unreserved memory cells in the partition; and

(d) if there are enough unreserved memory cells in the partition to store the file system structure;

(d1) storing the file system structure in the unreserved memory cells; and

(d2) storing a second file in the at least one memory cell reserved for the file system structure;

(e) if there are not enough unreserved memory cells in the partition to store the file system structure, storing the file system structure in the reserved at least one memory cell.

12. The method of claim 11 further comprising, before the act of reserving, determining a number of memory cells needed to store the file system structure.

13. The method of claim 11 wherein the file system structure comprises a file system structure selected from the group consisting of an allocation table, a listing of stored files, a search tree, a boot block, a partition header, a partition footer, a description of contents of the write-once memory device, and configuration information.

14. The method of claim 11, further comprising:

(e) locating a file or free memory cells in the partition using the file system structure stored in the reserved at least one memory cell.

15. The method of claim 11, wherein the reserved at least one memory cell is at an end of the partition.

16. The method of claim 11, wherein the memory device is logically organized into a plurality of blocks, each block comprising a plurality of lines;

and wherein the reserved at least one memory cell comprises a line.

17. The method of claim 16, wherein a line comprises a minimum number of memory cells that can be written into during a write operation.

18. The method of claim 11, wherein the memory device is logically organized into a plurality of blocks, each block comprising at least one line;

and wherein the reserved at least one memory cell comprises a block.

19. The method of claim 18, wherein a line comprises a minimum number of memory cells that can be written into during a write operation.

20. The method of claim 11, wherein the memory device comprises a three-dimensional write-once memory device.