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AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsTakuji Maeda, Teruto Hirota
Estimating the term…
A predetermined number of erasable blocks positioned at a start of a volume area in a semiconductor memory card include volume management information. A user area following the volume management information includes a plurality of clusters. A data length NOM of an area from a master boot record & partition table sector to a partition boot sector is determined so that the plurality of clusters in the user area are not arranged so as to straddle erasable block boundaries. Since cluster boundaries and erasable block boundaries in the user area are aligned, there is no need to perform wasteful processing in which two erasable blocks are erased to rewrite one cluster.
An access apparatus for performing file access on a semiconductor memory card that has a memory area comprising a plurality of sectors, by managing data in each group of 2j sectors (j being 0 or a positive integer) as a cluster, and managing one or more clusters as a file, each group of 2i consecutive sectors in the memory area forming a block (i being 0 or a positive integer), a block being a smallest unit on which data erasure can be performed, said access apparatus comprising:
A semiconductor memory card that has a memory area comprising a plurality of sectors, each group of 2i consecutive sectors in the memory area forming a block (i being 0 or a positive integer), a block being a smallest unit on which data erasure can be performed, data in each group of 2j sectors (j being 0 or a positive integer) among the plurality of sectors being managed as a cluster, one or more clusters being managed as a file, wherein:
An initialization method for initializing a computer to perform file access on a semiconductor memory card that has a memory area comprising a plurality of sectors by managing data in each group of 2j sectors (j being 0 or a positive integer) as a cluster, and managing one or more clusters as a file, each group of 2i consecutive sectors in the memory area forming a block (i being 0 or a positive integer), a block being a smallest unit on which data erasure can be performed, said initialization method comprising:
A recording medium storing a program in a computer-readable format for initializing a computer to have file access performed on a semiconductor memory card that has a memory area comprising a plurality of sectors, by managing data in each group of 2j sectors (j being 0 or a positive integer) as a cluster, and managing one or more clusters as a file, each group of 2i consecutive sectors in the memory area forming a block (i being 0 or a positive integer), a block being a smallest unit on which data erasure can be performed, said recording medium being operable to cause the computer to:
Dependencies are inferred from the claim text.
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Organizing or formatting or addressing of data: management of space entities, e.g. partitions, extents, pools
Improving I/O performance: in relation to throughput
Improving the reliability of storage systems: in relation to life time, e.g. increasing Mean Time Between Failures [MTBF]
Organizing or formatting or addressing of data: management of blocks
Term end not estimated
This application is based on an application No. 11-299636 filed in Japan, the content of which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to an access apparatus for accessing a semiconductor memory card having internal nonvolatile memory such as EEPROM (electrical erasable programmable read-only memory), a computer-readable recording medium for recording an initialization program for a semiconductor memory card, an initialization method, and a semiconductor memory card, and in particular to an improvement for raising the efficiency with which data can be rewritten in the nonvolatile memory.
These and other objects, advantages and features of the invention will become apparent from the following description thereof taken in conjunction with the accompanying drawings which illustrate a specific embodiment of the invention. In the drawings:
FIG. 1A shows a layout model formed from a physical layer, a file system layer compliant with ISO/IEC9293, and an application layer;
FIGS. 1B and 1C show the format of the physical layer and the file system layer;
The following is a description of embodiments of a semiconductor memory card, and of a system including a semiconductor memory card and an access apparatus, with reference to the drawings.
FIG. 2A shows an external view of a semiconductor memory card 100, and FIGS. 2B and 2C show external views of access apparatuses. FIG. 3A shows an internal structure of the semiconductor memory card 100 and an access apparatus 200.
The semiconductor memory card 100 has the external structure of FIG. 2A, being 32.0 mm long, 24.0 mm wide, and 2.1 mm thick: about the size of a postage stamp, and small enough for a user to hold on the tip of one finger. The semiconductor memory card 100 has nine connectors for connecting to an access apparatus 200, and a write protect switch 101 on one side, which can be set by the user to permit or prohibit overwriting of recorded data. As shown in the lower part of FIG. 3A, the semiconductor memory card 100 includes a nonvolatile memory 11 formed from NAND EEPROM, an access control unit 2, and a work memory 3. The access control unit 2 writes data into the nonvolatile memory 1, reads of data from the nonvolatile memory 1, and erases data, according to commands issued by the access apparatus 200. The work memory 3 is used for temporary data storage when data read from the nonvolatile memory is rewritten or written back into the nonvolatile memory.