Flash file management system

• US 5,832,493 A
• Filed: 04/24/1997
• Issued: 11/03/1998
• Est. Priority Date: 04/24/1997
• Status: Expired due to Term

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Manning, Charles David Hope, Marshall, Jonathan Miles
• Primary Examiner(s): Amsbury, Wayne
• Assistant Examiner(s): HAVAN, THU THAO
• Application Number:
  US08/847,459
• Time in Patent Office: 558 Days
• Field of Search: 707/101, 707/206, 364/400
• US Class Current: 707/697
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 16/902 using more than one table in sequence, i.e. systems with three or more layers
• CPC Class Codes: G06F 2212/7207 management of metadata or control data
• CPC Class Codes: G06F 2212/7209 Validity control, e.g. using flags, time stamps or sequence numbers
• CPC Class Codes: G06F 3/0616 in relation to life time, e.g. increasing Mean Time Between Failures [MTBF]
• CPC Class Codes: G06F 3/0619 in relation to data integrity, e.g. data losses, bit errors
• CPC Class Codes: G06F 3/0643 Management of files
• CPC Class Codes: G06F 3/0652 Erasing, e.g. deleting, data cleaning, moving of data to a wastebasket
• CPC Class Codes: G06F 3/0679 Non-volatile semiconductor memory device, e.g. flash memory, one time programmable memory [OTP]
• CPC Class Codes: G11C 16/349 Arrangements for evaluating degradation, retention or wearout, e.g. by counting erase cycles
• CPC Class Codes: Y10S 707/918 Location
• CPC Class Codes: Y10S 707/99942 Manipulating data structure, e.g. compression, compaction, compilation
• CPC Class Codes: Y10S 707/99953 Recoverability

Abstract

A flash memory using branded sectors for managing data files. The flash memory is divided into separately erasable blocks where each block may only be erased in its entirety. Each erasable block includes several file sectors, a sector allocation table (SAT) including an SAT record for each file sector, and a block information record (BIR) including status and an erasure count for the block. Each file sector may be designated as a file data sector, a file header sector, or block erasure sector. The data sectors include a data segment of one of the data files and is branded by a file identification and a sequence number. The brand and the size of the file sectors are used for locating the data sector for accessing the data segment. In order to prevent data from being lost during an update or a consolidation, each SAT record includes a pre-discard indicator for indicating when the associated data sector is being modified or consolidated and a discard indicator for indicating that the modification or consolidation has been completed. In order to prevent block information from being lost during an erasure, the block erasure sector includes the status and erasure counts for each of the erasure blocks.

Claims

1. A computer-readable memory with a particular data structure for enabling a computer to access data from a stored data file, the memory having bits capable of being erased only in blocks, comprising:

at least one separately erasable block organized to include two or more data sectors; and

each one of said data sectors for storing a data segment of said file, a file identification for identifying said file, and a sequence number for indicating a sequential position of said data segment within said file, the file identification and sequence number for enabling a computer to store, update, and subsequently read said data file without the use of a pointer to point from one said data segment to another said data segment.

2. The memory of claim 1, further including:

a pre-discard indicator controllable by said computer for indicating that a first of said data sectors is to be copied-to a second of said data sectors and a discard indicator controllable by said computer for indicating that said first data sector has been copied to said second data sector.

3. The memory of claim 1, wherein:

the erasure block is further organized to include at least one file header sector for storing at least one file record including information controllable by said computer for indicating at least one of (i) a length of said file, (ii) a checksum for said file;

(iii) a date for said file.

4. The memory of claim 1, wherein:

the erasure block is further organized to include an erasure count controllable by said computer for indicating a number of times the erasure block has been erased; and

a first of the erasure blocks is further organized to include a block erasure sector for storing at least one erasure record, each said erasure record controllable by said computer for indicating said erasure count corresponding to one of the erasure blocks, respectively.

5. The memory of claim 1, wherein:

the memory includes a flash memory.

6. A computing machine for storing, updating, and reading a data file, comprising:

a data memory having bits capable of being erased only in separately erasable blocks, at least one of said erasable blocks organized to include two of more data sectors, each one of said data sectors for storing a data segment of said file, a file identification for identifying said file, and a sequence number for indicating a sequential position of said data segment within said file;

a program memory having instructions for using said file identification and said sequence number for storing, updating, and reading said file; and

a processor coupled to the data memory and the program memory for executing said instructions.

7. The computing machine of claim 6, wherein:

the data memory further includes a pre-discard indicator and a discard indicator corresponding to a first of said data sectors; and

the program memory includes further instructions for marking said pre-discard indicator when said first data sector is to be copied to a second data sector and marking said discard indicator when said first data sector has been copied to said second data sector.

8. The computing machine of claim 6, wherein:

said erasure blocks are further organized to include at least one file header sector for storing at least one file record for indicating at least one of (i) a length of said file, (ii) a checksum for said file;

(iii) a date for said file.

9. The computing machine of claim 6, wherein:

each of said erasure blocks are further organized to include an erasure count indicative of the number of times said erasure block has been erased; and

a first of said erasure blocks is further organized to include a block erasure sector for storing at least one erasure record, each said erasure record controllable by said computer for indicating the erasure count corresponding to one of said erasure blocks, respectively.

10. The computing machine of claim 6, wherein:

the data memory includes a flash memory.

11. The computing machine of claim 6, further including:

a transducer/receiver for receiving data and issuing information for said data file.

12. The computing machine of claim 11, wherein:

the transducer/receiver includes a global positioning system (GPS) receiver for receiving a GPS signal and issuing said information corresponding to a geographical location.

13. A method in a computing machine for accessing a data file in a memory having bits capable of being erased only in blocks, comprising steps of:

organizing said memory into sectors;

designating one or more sectors as data sectors;

storing a data segment of said data file, a file identification for said data file, and a sequence number for a sequential position of said data segment within said data file in a first of said data sectors; and

using information based upon said file identification, said sequence number, and a size of said data sectors for retrieving said data segment.

14. The method of claim 13, further including steps of:

further organizing said memory for including a pre-discard indicator associated with each one of said data sectors;

further organizing said memory for having a discard indicator associated with each one of said data sectors;

marking said pre-discard indicator when said associated one of said data sectors is to be copied; and

marking said discard indicator when said associated one of said data sectors has been copied.