Semiconductor memory card access apparatus, a computer-readable recording medium, an initialization method, and a semiconductor memory card

• US 20070033335A1
• Filed: 10/12/2006
• Published: 02/08/2007
• Est. Priority Date: 10/21/1999
• Status: Active Grant

• Current Assignee: Takuji Maeda, Teruto Hirota
• Original Assignee: Takuji Maeda, Teruto Hirota
• Inventors: Maeda, Takuji, Hirota, Teruto
• Granted Patent: US 7,398,353 B2
• Time in Patent Office: Days
• US Class Current: 711/103
• CPC Class Codes: G06F 12/0223 User address space allocation, e.g. contiguous or non contiguous base addressing
• CPC Class Codes: G06F 12/0246 in block erasable memory, e.g. flash memory
• CPC Class Codes: G06F 12/1433 for a module or a part of a module
• CPC Class Codes: G06F 2212/1016 Performance improvement
• CPC Class Codes: G06F 2212/2022 Flash memory
• CPC Class Codes: G06F 2212/7202 Allocation control and policies
• CPC Class Codes: G06F 3/0613 in relation to throughput
• 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 3/0643 Management of files
• CPC Class Codes: G06F 3/0644 Management of space entities, e.g. partitions, extents, pools
• 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: G11B 20/00086 Circuits for prevention of unauthorised reproduction or copying, e.g. piracy indicating unauthorised use of record carriers in general G11B23/28; scrambling for television signal recording H04N5/913; network architectures or network protocols for network security H04L63/00; cryptographic mechanisms or cryptographic arrangements for secret or secure communication H04L9/00

Abstract

A predetermined number of erasable blocks positioned at a start of a volume area in a semiconductor memory card are provided so as to 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.

Claims

1. An access apparatus for performing file access on a semiconductor memory card that has a memory area comprising of a plurality of sectors, by managing one or more sectors as a cluster, and managing one or more clusters as a file, some consecutive sectors in the memory area forming a block, a block being a smallest unit on which data erasure can be performed, the block size being the power of 2 of the cluster size, the access apparatus comprising:

a calculation unit operable to calculate a size of volume management information based on a number of clusters in the memory area that are to be managed, the volume management information including a master boot record, a partition table, partition boot sector information, and a file allocation table that indicates, for each file, links between clusters corresponding to the file;

a reserving unit operable to reserve (1) a first area for recording the volume management information, and (2) a second area for recording user data, the first area being formed from blocks that are each larger in size than the calculated size of the volume management information, and the second area being formed from blocks following the first area; and

a recording unit operable to record volume management information in the first area, and user data in the second area, wherein

the recording unit is operable to record the master boot record and the partition table in a first sector of a first block in the first area and record the partition boot sector information, the file allocation table, and the predetermined number of reserved sectors which is used for padding of the first area, in order that a size of the first area is an integral multiple of the block size.

2. The access apparatus of claim 1, wherein:

the calculation unit is operable to calculate a sum SUM by totaling a number of sectors used to record the partition boot sector information and the file allocation table;

the first area is formed from 2^j×

m sectors (j being 0 or a positive integer, m being a positive integer);

the reserving unit is operable to calculate the value of m based on {equation 1}

NOM+SUM=2^j×

m, 

 

{equation 1}

NOM being a number of sectors; and

the recording unit is operable to calculate the predetermined number of sectors by subtracting 1 from the number of sectors NOM.

3. The access apparatus of claim 2, wherein:

the recording unit is operable to set the number of sectors NOM in the partition table when recording the volume management information.

4. The access apparatus of claim 2, wherein:

the number of sectors used to record the file allocation table is based on the number of clusters in the memory area that are to be managed.

5. The access apparatus of claim 4, wherein:

the file allocation table has a plurality of entries, a number of entries corresponding to a number of clusters recorded in the second area, and each entry showing a link to another cluster in a same file;

the access apparatus comprises;

a reception unit operable to receive a setting for a total number of sectors and the number of clusters in the memory area;

the calculation unit includes;

a first calculation unit operable to calculate a total number of clusters by dividing the total sector number by the number of sectors, and to calculate a size of the file allocation table by multiplying the total number of clusters by an entry bit length, and

the reserving unit includes;

a second calculation unit operable to calculate a sum SUM by adding the size of the file allocation table to the number of sectors forming the partition boot sector information, and to calculate the value of m by substituting the sum SUM into {equation 1}.

6. The access apparatus of claim 5, wherein:

the memory area includes a protected area that can only be accessed by a device connected to the semiconductor card once an authenticity of the connected device has been verified, and

a user data area that can be accessed by the connected device regardless of whether or not the authenticity of the connected device has been verified;

the reception unit is operable to receive, from a source outside of the access apparatus, settings for numbers of sectors and numbers of clusters to be allocated to each of the protected area and the user data area;

the first calculation unit is operable to calculate a size of a file allocation table for each of the protected area and the user data area, based on the received settings; and

the second calculation unit is operable to calculate two sums SUM for each of the protected area and the user data area respectively by adding the size of the file allocation table to the number of sectors forming the partition boot sector information, and to calculate the value of m for each of the protected area and the user data area by substituting each of the two sums SUM into {equation 1}.

7. The access apparatus of claim 6, wherein:

the protected area and the user data area have different numbers of clusters.

8. The access apparatus of claim 5, wherein the recording unit is operable to perform:

(a) first processing for recording user data divided into a plurality of sections into the second area as a plurality of clusters, each section being stored in one of the plurality of clusters in the second area;

(b) second processing for setting a plurality of entries in the file allocation table, each entry showing a link between clusters; and

(c) third processing for recording a file name and location information showing a location of a first cluster in the file into the root directory entry.

9. The access apparatus of claim 8, wherein part of the file name is recorded in part of the user data area.

10. A recording medium storing a program in a computer-readable format for causing a computer to perform file access on a semiconductor memory card that has a memory area comprising of a plurality of sectors, by managing one or more sectors as a cluster, and managing one or more clusters as a file, some consecutive sectors in the memory area forming a block, a block being a smallest unit on which data erasure can be performed, the block size being the power of 2 of the cluster size, the recording medium having the computer perform the following steps of:

calculating a size of volume management information based on a number of clusters in the memory area that are to be managed, the volume management information including a master boot record, a partition table, partition boot sector information, and a file allocation table that indicates, for each file, links between clusters corresponding to the file;

reserving (1) a first area for recording the volume management information, and (2) a second area for recording user data, the first area being formed from blocks that are each larger in size than the calculated size of the volume management information, and the second area being formed from blocks following the first area; and

recording volume management information in the first area, and user data in the second area, wherein

the recording step records the master boot record and the partition table in a first sector of a first block in the first area and records the partition boot sector information, the file allocation table, and the predetermined number of reserved sectors which is used for padding of the first area, in order that a size of the first area is an integral multiple of the block size.

11. The recording medium of claim 10, wherein:

the calculating step calculates a sum SUM by totaling a number of sectors used to record the partition boot sector information and the file allocation table;

the first area is formed from 2^j×

m sectors (j being 0 or a positive integer, m being a positive integer);

the reserving step calculates the value of m based on {equation 1}

NOM+SUM=2^j×

m,  

 

{equation 1}

NOM being a number of sectors; and

the recording step calculates the predetermined number of sectors by subtracting 1 from the number of sectors NOM.

12. The recording medium of claim 11, wherein:

the recording step sets the number of sectors NOM in the partition table when recording the volume management information.

13. The recording medium of claim 12, wherein:

the number of sectors used to record the file allocation table is based on the number of clusters in the memory area that are to be managed.

14. The recording medium of claim 13, wherein:

the file allocation table has a plurality of entries, a number of entries corresponding to a number of clusters recorded in the second area, and each entry showing a link to another cluster in a same file;

the program comprises the step of;

receiving a setting for a total number of sectors and the number of clusters in the memory area;

the calculating step includes the first sub-step of;

calculating a total number of clusters by dividing the total sector number by the number of sectors, and calculating a size of the file allocation table by multiplying the total number of clusters by an entry bit length, and

the reserving step includes the second sub-step of;

calculating a sum SUM by adding the size of the file allocation table to the number of sectors forming the partition boot sector information, and calculating the value of m by substituting the sum SUM into {equation 1}.

15. The recording medium of claim 14, wherein:

the memory area includes a protected area that can only be accessed by a device connected to the semiconductor card once an authenticity of the connected device has been verified, and a user data area that can be accessed by the connected device regardless of whether or not the authenticity of the connected device has been verified;

the receiving step receives, from a source outside of the access apparatus, settings for numbers of sectors and numbers of clusters to be allocated to each of the protected area and the user data area;

the first sub-step calculates a size of a file allocation table for each of the protected area and the user data area, based on the received settings; and

the second sub-step calculates two sums SUM for each of the protected area and the user data area respectively by adding the size of the file allocation table to the number of sectors forming the partition boot sector information, and calculates the value of m for each of the protected area and the user data area by substituting each of the two sums SUM into {equation 1}.

16. The recording medium of claim 15, wherein:

the protected area and the user data area have different numbers of clusters.

17. An initialization method for initializing a computer to perform file access on a semiconductor memory card that has a memory area comprising of a plurality of sectors, by managing one or more sectors as a cluster, and managing one or more clusters as a file, some consecutive sectors in the memory area forming a block, a block being a smallest unit on which data erasure can be performed, the block size being the power of 2 of the cluster size, the initialization method comprising the steps of:

calculating a size of volume management information based on a number of clusters in the memory area that are to be managed, the volume management information including a master boot record, a partition table, partition boot sector information, and a file allocation table that indicates, for each file, links between clusters corresponding to the file;

reserving (1) a first area for recording the volume management information, and (2) a second area for recording user data, the first area being formed from blocks that are each larger in size than the calculated size of the volume management information, and the second area being formed from blocks following the first area; and

recording volume management information in the first area, and user data in the second area, wherein

the recording step records the master boot record and the partition table in a first sector of a first block in the first area and records the partition boot sector information, the file allocation table, and the predetermined number of reserved sectors which is used for padding of the first area, in order that a size of the first area is an integral multiple of the block size.

18. A semiconductor memory card that has a memory area that has a memory area comprising of a plurality of sectors, by managing one or more sectors as a cluster, and managing one or more clusters as a file, some consecutive sectors in the memory area forming a block, a block being a smallest unit on which data erasure can be performed, the block size being the power of 2 of the cluster size, the semiconductor memory card comprising:

a first area for recording volume management information; and

a second area, being formed from sectors following the first area, for recording user data;

the volume management information including a master boot record, a partition table, partition boot sector information, and a file allocation table that indicates, for each file, links between clusters corresponding to the file,

the master boot record and the partition table are recorded in a first sector of a first block in the first area; and

the partition boot sector information, the file allocation table, and the predetermined number of reserved sectors, which is used for padding of the first area, are recorded in subsequent sectors in order that a size of the first area is an integral multiple of the block size.

19. A semiconductor memory card having a memory area that includes (1) a protected area that can only be accessed by a device connected to the semiconductor card once an authenticity of the connected device has been verified, and (2) a user data area that can be accessed by the connected device regardless of whether or not the authenticity of the connected device has been verified, the protected area and the user data area including a plurality of sectors, and managing one or more sectors as a cluster, and one or more clusters as a file, some consecutive sectors forming a block, a block being a smallest unit on which data erasure can be performed, the block size being the power of 2 of the cluster size, and at least one of the protected area and the user data area including:

a first area for recording volume management information; and

a second area, being formed from sectors following the first area, for recording user data;

the volume management information including a master boot record, a partition table, partition boot sector information, and a file allocation table that indicates, for each file, links between clusters corresponding to the file,

the master boot record and the partition table are recorded in a first sector of a first block in the first area; and

the partition boot sector information, the file allocation table, and the predetermined number of reserved sectors, which is used for padding of the first area, are recorded in subsequent sectors in order that a size of the first area is an integral multiple of the block size.