Electrical computers and digital processing systems: memory – Storage accessing and control – Specific memory composition
Reexamination Certificate
2001-03-26
2002-06-04
KIm, Matthew (Department: 2186)
Electrical computers and digital processing systems: memory
Storage accessing and control
Specific memory composition
C711S173000, C713S002000
Reexamination Certificate
active
06401166
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to data processing system using block erasing type memory device, block erasing type memory device and computer readable program memory medium storing program for formatting, data erasing and date write for block erasing type memory device.
Recently, a flash memory has been used as a portable nonvolatile memory medium instead of a floppy disk, particularly as a memory medium for a mobile information terminal. The flash memory mentioned herein refers to a nonvolatile block erasing type memory device comprising a plurality of blocks, in which data stored internally can be electrically erased by each block.
When the flash memory is used under a control of such a disk operating system as MS-DOS (Microsoft's trademark), it is formatted according to the same format as that used conventionally for the floppy disk so as to handle it in the same way as the floppy disk. According to this format, a memory area is divided to boot area, FAT (file allocation table) area, directory area and data area. The data area is logically divided to clusters according to a definition stored in the boot area and a file to be stored in the flash memory is memorized in units of one cluster.
However, in the format of the conventional flash memory, the position of the cluster does not coincide with that of a block.
Therefore, if it is intended to update data (file) stored in a cluster, data (file) not necessary to update is also erased in units of a block altogether. Thus, the data not necessary to update must be saved in other cluster.
The same problem occurs when data (file) is written into a flash memory.
Further, if erasing or write-in of data is executed, FAT or directory must be rewritten, so that correspondingly the data not necessary to erase must be saved in other block.
Therefore, in order to update a single file in a conventional block erasing type memory device, plural blocks must be updated even if it is data within one block. For the reason, data write processing is divided to two parts so that it takes a long time, thereby often leading to deceleration of the entire memory device operation.
The same problem occurs when data (file) is written into the flash memory.
Further, if erasing or write-in of data is executed, FAT or directory must be rewritten, so that correspondingly the data not necessary to erase must be saved in other block.
This problem becomes more conceivable when data processing unit such as CPU controls the block erasing type memory device through a direct access thereto without using a special controller for reduction of the size and power consumption of the memory device.
BRIEF SUMMARY OF THE INVENTION
An object of the present invention is to accelerate data access, particularly processing including data erasing in the block erasing type memory device.
Another object of the invention is to provide a block erasing type memory device having a format structure capable of achieving data write-in processing rapidly and making the best use of the storage capacity, data processing system using the same memory medium and a program memory medium storing a program for formatting of the block erasing type memory device, data erasing and data write-in.
According to a first aspect of the present invention, there is provided data processing system comprising a block erasing type memory device including a plurality of blocks, capable of erasing stored data collectively in units of one block and data processing means for accessing the block erasing type memory device, wherein the data processing means includes a formatting portion connected to the block erasing type memory device for formatting the block erasing type memory device according to formatting information for substantially coinciding the size and position of a cluster as a logical unit of a memory region of the block erasing type memory device with those of integer ones of the blocks, and an access control portion for determining the size and position of the cluster according to the format information and carrying out access control for data erasing, data write-in and data read-out for the block erasing type memory device according to the determined size and position of the cluster.
In this data processing system, a cluster includes integer ones of the blocks. Thus, data erasing and write-in processing can be carried out in units of one block. Thus, the necessity of saving other data for data write-in or erasing is eliminated, so that the data erasing and write-in processing can be carried out rapidly.
According to a second aspect of the present invention, there is provided a block erasing type memory device having a format information memory region for storing format information for making integer ones substantially correspond to a cluster serving as a unit of data memory region and capable of erasing stored data collectively in units of one block.
In this block erasing type memory device, the cluster includes integer ones. Thus, data erasing and write-in processing can be carried out in units of one block. Thus, the necessity of saving other data for data write-in is eliminated, so that the data erasing and write-in processing can be carried out rapidly.
Although ordinarily, the cluster has a single block, it may be formed of a plurality of the blocks.
The format information comprises information for corresponding the size of the cluster with the size of the block and a position adjusting region for coinciding a start position and end position of each of the clusters with the start position and end position of the block, for example, an empty region.
The block erasing type memory device may store directory information indicating a file name and head memory position and a file allocation table indicating a file position in a single cluster.
When data is stored in a memory medium, ordinarily it is necessary to memorize position information (e.g., file allocation table) indicating which position each data is stored and identification name (e.g., file name and directory) of each data. This position information and identification name must be updated each time when data write-in or erasing is carried out. In the above block erasing type memory device, the position information and identification name are stored in a single cluster or a single block. Therefore, the necessity of saving other data for updating these data is eliminated. Thus, the data write-in or erase processing can be carried out rapidly.
It is preferred that stored data of blocks other than the aforementioned block including the block for storing the format information is physically erased.
In general memory medium, it is possible to consider that data has been erased by replacing a particular portion of the data (e.g., head one character) with a specific code, without physically erasing data stored in the data region (e.g., erasing by writing data corresponding to “1”).
However, in the block erasing type memory device like the flash memory, by such data erasing method, new data cannot be written over the erased data, so that the processing for saving the original data and erasing its appropriate area is required.
Because according to the present invention, in other regions than such particular regions as boot region and FAT region and the like, data has been erased, saving of data and erasing upon write-in processing become unnecessary, so that the write-in processing can be accelerated.
According to a third aspect of the present invention, there is provided data processing system comprising a connecting portion containing a plurality of blocks and so constructed to be connectable to a block erasing type memory device capable of erasing collectively stored data in units of one block and a formatting portion for formatting the block erasing type memory device by writing format information for substantially coinciding integer ones of the blocks, for example, one block with a cluster into the block erasing type memory device through the connecting portion.
According to this system, the cluster includes integer one
KIm Matthew
Peugh B. R.
Pillsbury & Winthrop LLP
Tokyo Electron Device Limited
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