Data access method capable of reducing the number of erasing to flash memory and data patch and access device using the same

• US 6,256,232 B1
• Filed: 07/07/2000
• Issued: 07/03/2001
• Est. Priority Date: 07/07/2000
• Status: Active Grant

• Current Assignee: Acer, Inc.
• Original Assignee: Institute For Information Industry
• Inventors: Chang, Li-Pin, Lee, Tzao-Lin, Chen, Hsiao-Hui, Cheng, Huey
• Primary Examiner(s): LE, VU ANH
• Application Number:
  US09/612,631
• Time in Patent Office: 361 Days
• Field of Search: 365/185.33, 365/185.01, 365/185.29, 395/500, 711/6
• US Class Current: 365/185.33
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 3/0616 in relation to life time, e.g. increasing Mean Time Between Failures [MTBF]
• 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]
• CPC Class Codes: G11C 16/102 External programming circuits, e.g. EPROM programmers; In-circuit programming or reprogramming; EPROM emulators

Abstract

A data access method capable of reducing the number of erasing to flash memory and a data patch and access device that utilizes the method are disclosed. A data write procedure is provided for determining a difference between data to be written and existed data in the data block when writing data to a data block of the flash memory, and if the difference is less than a pre-determined value, writing the difference to a patch area instead of writing the data to the data block. A data read procedure is provided for searching the difference recorded in the patch area when reading data from a data block of the flash memory, so as to patch the data.

Claims

1. A data access method for reducing the number of erasing to flash memory comprising:

a data write procedure for determining a difference between data to be written and existed data in the data block when writing data to a data block of the flash memory, and if the difference is less than a pre-determined value, writing the difference to a patch area instead of writing the data to the data block; and

a data read procedure for searching the difference recorded in the patch area when reading data from a data block of the flash memory, so as to patch the data.

2. The data access method for reducing the number of erasing to flash memory as claimed in claim 1, wherein in the data write procedure, at least a patch record is produced by comparing the data to be written and the existed data on the data block.

3. The data access method for reducing the number of erasing to flash memory as claimed in claim 2, wherein, when the patch area has enough space and the patch record has a total length smaller than a threshold value, the patch record is written into the patch area.

4. The data access method for reducing the number of erasing to flash memory as claimed in claim 3, wherein, if the patch area does not have enough space, a general flash memory write operation is performed to write the data to the data block.

5. The data access method for reducing the number of erasing to flash memory as claimed in claim 2, wherein, when the patch record has a total length greater than a threshold value, a general flash memory write operation is performed to write the data to the data block.

6. The data access method for reducing the number of erasing to flash memory as claimed in claim 2, wherein, when the patch record has a total length of zero, no substantial write operation is performed.

7. The data access method for reducing the number of erasing to flash memory as claimed in claim 3, wherein, in the data read procedure, a corresponding patch record is found in the patch area, so as to patch the data based on the patch record.

8. The data access method for reducing the number of erasing to flash memory as claimed in claim 3, further comprising a data segment callback procedure to recycle void data blocks.

9. The data access method for reducing the number of erasing to flash memory as claimed in claim 8, wherein the data segment callback procedure comprising the steps of:

reading data blocks which is still in use based on the data read procedure for being temporarily stored in memory;

erasing content of the segment of the flash memory; and

copying the data block which is temporarily stored in memory back to the data block of the flash memory.

14. The data patch and access device as claimed in claim 2, wherein, when the patch record has a total length greater than a threshold value, the data write means performs a general flash memory write operation to write the data to the data block.

10. A data patch and access device for reading and writing flash memory, the flash memory having multiple data blocks, at least a data block corresponding to a patch area, the device comprising:

a data write means for determining a difference between data to be written and existed data in the data block when writing data to a data block of the flash memory, and if the difference is less than a pre-determined value, writing the difference to a patch area instead of writing the data to the data block; and

a data read means for searching the difference recorded in the patch area when reading data from a data block of the flash memory, so as to patch the data.

11. The data patch and access device as claimed in claim 10, wherein the data write means produces at least a patch record by comparing the data to be written and the existed data on the data block.

12. The data patch and access device as claimed in claim 10, wherein, when the patch area has enough space and the patch record has a total length smaller than a threshold value, the data write means writes the patch record into the patch area.

13. The data patch and access device as claimed in claim 12, wherein, if the patch area does not have enough space, the data write means performs a general flash memory write operation to write the data to the data block.

15. The data patch and access device as claimed in claim 11, wherein, when the patch record has a total length of zero, the data write means does not perform any substantial write operation.

16. The data patch and access device as claimed in claim 12, wherein, the data read means finds a corresponding patch record in the patch area, so as to patch the data based on the patch record.

17. The data patch and access device as claimed in claim 10, further comprising a data segment callback means to recycle void data blocks.

18. The data patch and access device as claimed in claim 17, wherein the data segment callback means performs the following steps:

reading data blocks which is still in use based on the data read procedure for being temporarily stored in memory;

erasing content of the segment of the flash memory; and

copying the data block which is temporarily stored in memory back to the data block of the flash memory.