Error detection/correction and fault detection/recovery – Data processing system error or fault handling – Reliability and availability
Reexamination Certificate
1998-10-02
2001-05-22
Beausoleil, Robert (Department: 2184)
Error detection/correction and fault detection/recovery
Data processing system error or fault handling
Reliability and availability
C711S103000, C711S165000
Reexamination Certificate
active
06237110
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a flash memory device, particularly to an apparatus and a method for accessing (reading from and writing in) a plurality of flash memory blocks.
BACKGROUND OF THE INVENTION
Conventional memory devices, either hard disks or floppy disks, are made from material characterized by magnetism, and thereby with access speed inevitably limited by the control mechanism of their access heads.
Furthermore these conventional memory devices may easily be so affected by environmental conditions such as temperature, humidity, or shocks, that the data stored therein may likely get lost or damaged, raising troubles to users.
Usually limited by structures and storage density (capacity per unit of size), IC memories such as RAM and ROM or the like are not suitable for the applications where both size and capacity as well as reliability shall be elaborate.
Developments of various devices have been tried to solve the above problems, among which a solid state disk based on flash memories is quite significant. Therefore the achievement of an apparatus and method for reliably and rapidly accessing the flash memories are widely expected by related industries, especially the realization of an apparatus and method for detouring a fundamental difference between a flash memory device and a conventional memory device is critically expected for easy application. The fundamental difference is that a flash memory device doesn't work in a way of having the data saved (written) in a memory cell (or unit) therein replaced by new data written in the same cell later, as does a conventional memory device. A flash memory device must be formatted into a plurality of blocks each comprising many data memory units each for writing a piece or a set of data therein for only once. Unless a whole block is cleaned (all the data memory units therein are cleaned), any data memory unit which has already had data saved (or written) therein can no longer be written.
SUMMARY OF THE INVENTION
The primary object of the present invention is to provide an apparatus and method for reliably and rapidly accessing (writing data in and/or reading data from) flash memories while maintaining data integrity.
Another object of the present invention is to provide a detection apparatus and method for significantly promoting the reliability of accessing flash memories.
The apparatus provided by the present invention for accessing data therein (writing data in and/or reading data out by a computer or a logic interface, for example) may be configured to be a memory device comprising:
a plurality of flash memory blocks each being assigned an identification code (a binary number, for example) and each including at least one data memory unit and at least one pointer memory unit, the flash memory block to be assigned (by a computer or a logic interface, for example) for accessing the data memory unit thereof; and
a plurality of spare flash memory blocks each also being assigned an identification code and also including at least one data memory unit and at least one pointer memory unit.
The data memory unit of the spare flash memory block is for writing at least a piece of overwritten data of the flash memory blocks that is assigned for accessing (writing), the pointer memory unit of the flash memory block for recording the identification code of the spare flash memory block wherein said overwritten data is written, the pointer memory unit of the spare flash memory block for recording the identification code of the flash memory block where the writing of the overwritten data in the data memory unit thereof had been tried but not done because the data memory unit has already had data written therein, and said overwritten data has to be written in the data memory unit of a spare flash memory block, thereby said overwritten data can be saved in the data memory unit of one spare flash memory block, whereby the fundamental difference between a flash memory device and a conventional memory device can be detoured, leading to satisfactory and easy application of flash memories.
The memory device may also comprise at least one reservation flash memory block being assigned an identification code and for substituting the flash memory block and/or the spare flash memory block which fail/fails.
The memory device may further comprises at least one failure management block for recording the identification codes of the flash memory block and the spare flash memory block which fail, and the identification codes of the reservation flash memory blocks substituting the flash memory block and spare flash memory block which fail.
The data memory unit may be configured to comprise a plurality of memory positions each for writing therein a piece of data or a set of data (at least a piece of data) which of course can be read out. Obviously the flash memory block may also be configured to comprise a plurality of data memory units each, as a memory unit (cell) like the above memory position, can be written therein a piece of data or a set of data (at least a piece of data) which of course can be read out. The specification disclosed hereinafter will focus on an embodiment based on the former condition where the data memory unit comprises a plurality of memory positions each for writing therein a piece of data or a set of data (at least a piece of data) which of course can be read out.
The pointer memory unit includes a primary data memory status pointer for recording each written memory position which is a memory position (in the data memory unit of the same flash memory block, for example) where there has been data written therein, and a terminal data memory status pointer for recording each overwritten memory position.
The memory device may have the pointer memory unit of the flash memory block thereof further for recording the identification code of the spare flash memory block where the overwritten data is written in the data memory unit thereof, and have the pointer memory unit of the spare flash memory block thereof for recording the identification code of the flash memory block where the writing of the overwritten data in the data memory unit thereof had been tried but not done because the data memory unit had already have at least one memory position therein been written (or saving) data.
The memory device may have the pointer memory unit of the flash memory block further recording attribute data for distinguishing the flash memory block from the spare flash memory block, and the pointer memory unit of the spare flash memory block further recording attribute data for distinguishing the spare flash memory block from the flash memory block.
The memory device may further comprise an address allocation device and an addressing circuit, the address allocation device for providing the identification code of the flash memory block to be assigned for accessing data therein, the addressing circuit for addressing the flash memory block and the spare flash memory block to be accessed.
An access method characterizing one embodiment of the present invention is for accessing a memory system which includes a plurality of flash memory blocks each having an identification code assigned thereto and each including at least a data memory unit and a pointer memory unit, and includes a plurality of spare flash memory blocks each also having an identification code assigned thereto and also including at least a data memory unit and a pointer memory unit, the pointer memory unit for recording guiding data which includes flag data indicating each written memory position and each overwritten memory position in the data memory unit. The access method comprises a writing process for writing at least a piece of data in a corresponding position in the data memory unit of one of the plurality of flash memory blocks. The writing process comprises the steps of
a. assigning a flash memory block to be an access flash memory block;
b. reading the guiding data in the pointer memory unit of the access flash memory block;
c. if the guiding data in the
Lin Chanson
Shyu Joe
Baderman Scott T.
Beausoleil Robert
Kye Technology Corporation
Rosenberg , Klein & Lee
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