JP2000285000A - File system for nonvolatile memory - Google Patents

Abstract

PROBLEM TO BE SOLVED: To speedily write data without erasing at the time of writing by writing data in a flash memory by a size equal to or larger than an erasing size so as to write speedily to previously execute erasing processing. SOLUTION: Area management is executed by a Space Bitmap for managing an unused area where data are not erased and another Space Bitmap for managing an unused area where data are erased. In order to manage the presence and absence of the data in the unused areas, Unallocated space Bitmap 611 and Freed Space Bitmap 614 are used, and in order to manage an area of different size for writing speedily, the Unallocated space Bitmap 611 and Fragment Space Bitmap 615 are used. Unallocated space Bitmap 613 manages an area where unused data are already erased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data structure of a recording medium for recording a digital work, and to an apparatus for accessing the recording medium.

[0002]

2. Description of the Related Art In recent years, with the development of multimedia network technology, digital contents such as music have been distributed through the Internet and the like, and the user has access to music and the like from all over the world while staying at home. Has become possible. Such music content and the like can be recorded on a recording medium such as a nonvolatile semiconductor memory and a flash memory. Music content recorded on a recording medium such as a semiconductor memory is read and reproduced by, for example, a portable music reproducing device.

[0003] When data is recorded on a recording medium, a concept of a file is used to make it easy to handle data having a coherent content in units. The management information to be managed can be recorded as a pair. The management information is, for example, information indicating an attribute such as permission / inhibition of the file, a size, a position of the file, and the like, and the file can be accessed by referring to the management information. The mechanism that handles this file is called a file system.

[0004]

However, conventionally,
It has been assumed that a flash memory used as a recording medium for recording contents is used as auxiliary storage for a computer. When writing to the flash memory, it is not a data structure optimized for the characteristics of the flash memory, but is based on the JIS-X-0605 standard F for compatibility.
Because it uses a data structure of the format called AT,
Could not write at high speed. In a portable music playback device, it is assumed that the user writes in the flash memory at the time before going to work or going to school in the morning, and therefore it is required that the writing be completed in as short a time as possible. That is,
It is required to write contents downloaded from the Internet to a flash memory as quickly as possible.

When used in a portable music player for consumer use, even if an emergency such as a power failure occurs while writing data to the flash memory, data in the flash memory is not destroyed as much as possible. You need to take the structure.

Accordingly, the present invention has been made in view of such a demand, and a digital work has been recorded with an optimal data structure in terms of use and security of a nonvolatile semiconductor memory and a flash memory. It is an object to provide a digital work recording medium and an access device therefor.

[0007]

According to the present invention, there is provided a digital work medium including a logical block of a file system which handles digital work data as a file, and a data area of the file, which is a data area in a nonvolatile memory. An AV block having the same size as the file, a file entry for managing the file name and the file attribute, and a management information area for managing the free area of all blocks have two types of logical block structures: a management block having the same size as the sector size. It is characterized by the following.

[0008] The present invention is characterized in that a function is provided for allocating data of the management block from the AV block, and when there is a vacancy in the management block, the data is continuously arranged as the AV block.

A file system that handles digital copyrighted work data as a file manages a logical block in a nonvolatile memory as a free list of blocks that need to be erased for writing, and the logical block has already been erased. It has a structure for managing blocks as an erased free list.

Also, by assigning an AV attribute to a file of digital copyrighted work data to be divided / combined,
In the case of the attribute, the division / combination processing unit operates and has an AV attribute determination function of making the additional recording / overwriting processing unit inactive.

[0011] The present invention is also characterized in that it has a function of changing the correspondence between the logical blocks and the physical blocks of the nonvolatile memory and continuously allocating the arrangement of the logical blocks of the file.

[0012] Further, two or more copies of a volume management area for managing all logical blocks in the nonvolatile memory are provided, and the volume management area and the copy of the volume management area are provided with identification numbers, and the volume management area is stored in the nonvolatile memory. The feature is that it is an integral multiple of the erase size of the memory.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The data structure of a digital work recording medium according to the present invention will be described below with reference to the drawings.

<1. Media Card> A portable recording / reproducing apparatus (hereinafter, a semiconductor player) reproduces music data recorded on a digital work recording medium (hereinafter, a media card). The media card is a rewritable non-volatile memory that can be repeatedly written over and over, and has a capacity of 64 MB. The media card has a thickness of about 2 mm and a size of about 2 cm square, and has an active element having functions such as mutual authentication, access control of the flash memory, and save processing, in addition to the flash memory.

Due to the characteristics of the flash memory, the minimum read / write unit of the media card can be set to the sector size (512 bytes).
The size is in units of a cluster size (16 KB).
Therefore, when writing of a size smaller than that, for example, 512 bytes occurs, it is necessary to perform a save process of writing with the remaining portion of 16 KB.

The operation of the saving process will be described with reference to FIG. 1. A write request of 16 KB or less (512 bytes) occurs (S101) 2. The data (16 KB) of the cluster to be written is saved on the memory (S102) 3. The data (512 bytes) of the write portion on the memory is Change (S103) 4. The cluster data at the write position on the medium (16
(KB) is erased (S104) 5. Data (16 KB) in the memory is written to the flash memory (S105) Therefore, when writing data of 16 KB or less, the data must first be saved on the memory and then written. Will be written in portions other than the portion where it is desired to perform. Therefore, writing at a time of writing 16 KB data that does not save the data at a time is faster than writing data of 16 KB or less a plurality of times.
Further, since the media card has a life for the number of times of writing that it cannot be written any more after 300,000 times, it is necessary to reduce the number of times of writing as much as possible. From that point, it is necessary to write 16 KB data collectively.

<2. Regarding UDF> FIG. 2 shows a logical format stored in the flash memory, UDF (Uni).
FIG. 4 is a schematic diagram of the “versalDiskFormat”.
In UDF, V is added to each of the first and last 257 sectors of the volume.
An olume Structure 200 exists and stores management information of the entire volume. Second half Volume Structure220
Is a copy of the first half of the Volume Structure 200, and exists for recovery from a failure when the first half of the Volume Structure 200 is destroyed. Two Volume
A File Structure 210 that actually stores file data and the like exists between the Structures 200 and 220.

FIG. 3 is a schematic diagram of the File Structure 300. In the File Structure 300, the part, Partit
File Set Descriptor 301 that stores ion information, File
Terminating Descri indicating the end of SetDescriptor 301
ptor302, stores Space Bitmap for area management
Space Bitmap Descriptor 303, File Entry 304 for storing file information, File Identifier Descriptor 320 for storing File information in a directory, file data, and the like are stored.

<3. About Volume Structure> UDF
In this example, two 256 sector areas are reserved for Volume Structures 200 and 220. Also, Volume Structur
A reserved area of 15 sectors is secured between e200, 220 and File Structure 210. Since a semiconductor player has a limited area, unnecessary sectors must be eliminated as much as possible.

A part of the Volume Structures 200 and 220 needs to be updated when a file is created or deleted. The data changed here is Volume Structure
However, due to the characteristics of the media card described above, data writing is performed at the highest speed in units of 16 KB.
It is desirable that writing of 0 and 220 is also performed in units of 16 KB.

From these points, Volume Structure 20
It is effective to extract only useful portions of 0 and 220 and store them in a 16 KB cluster. However Volu
Since 16 KB does not exist as a useful portion in the me Structures 200 and 220, 16 KB can be used effectively by including a part of the management information of the Partition described in the File Structure 210 here.

FIG. 4 is a schematic diagram of the volume format of the present invention. In this format, similar to the UDF format, Volume Structures 400 and 440 storing volume management information at the beginning and end of the volume.
Exists, between which file data is stored
File Structure 420 exists.

<3.1 Use of a Plurality of Volume Structures> Since the upper limit of the number of times of writing is determined as a characteristic of the media card, it is necessary to avoid concentration of writing in the same sector. Therefore, prepare two Volume Structures 400 and 440 with the same structure,
Volume Structu alternately every time management information is updated
re400 and 440 are updated. Two Vols when updating
IDs managed in common by ume Structure400 and 440
The value is incremented so that the latest management information always holds a large value. By doing so, writing of management information to the Volume Structures 400 and 440 is distributed to two clusters, and the life of the media card can be extended. Either Volume Structure 4
If 00 and 440 are broken, unbroken Volume S
Using the tructures 400 and 440, if both are not broken, use the one with the larger ID value.

Further, the number of Volume Structures 400 and 440 is not limited to two, and it is also possible to prepare more numbers. By doing so, it becomes more resistant to failure and the number of times of writing is also distributed.

<3.2 Part of File Structure is Volume
Regarding inclusion in the same cluster as Structure> UD
In F, Space Bitmap 423 is arranged in File Structure 420. Since the Space Bitmap 423 is data indicating the use or non-use of a sector in the media card, it is frequently changed when a file is created or updated, and a sudden power failure occurs during recording. In consideration of the situation, such as protection of a recorded song, it is necessary to write to a medium every time a song has been recorded. In such a case, the number of times of writing to the same sector increases, and there is a problem that the life of the sector is shortened due to the limitation of the number of times of writing of the media card described above.

Therefore, File S such as Space Bitmap 423
The management information contained in the tructure 420 is
by placing it after the Volume 400
The same cluster as 0, Volume Structure 4 described above
In the same manner as when a plurality of write sectors 00 and 440 are provided, write sectors are dispersed to extend the write life.

Further, high-speed writing is performed by storing the data in the same 16 KB area as the Volume Structures 400 and 440.

<4. Regarding UDF Area Management Method> FIG. 5 is a schematic diagram of a UDF area management method. In UDF
Partition Descriptor in Volume Structure 500
Reference numeral 501 denotes a method of managing the area of a Partition. P
Partition Contents Us in artition Descriptor 501
In the e502 field, an address and a size of a Bitmap area for area management used in the Partition are described. The actual area management is performed by using a Bitmap or
Performed on the Table. UDF uses Space as a space management method.
It supports Bitmap and Space Table, but has a restriction that you must not use both at the same time. Space
Bitmaps 511 and 514 have a bit information of the same number as the total number of sectors to be managed, and are a method of managing the use and non-use of the area by the bits 0 and 1. Space Table 510, 513
Is a method of describing and managing an unused area by a combination of a start position and an area size. Unallocated Space5
Reference numerals 10 and 511 denote unused areas for managing areas that can be written immediately. Freed Space 513, 51
Reference numeral 4 denotes an unused area which manages an area which requires preprocessing before writing and cannot be written immediately.

<5. Regarding Area Management Method of Semiconductor Player> When data is written to a media card in a semiconductor player, in an area where data has already been written, the data must be erased once and then written. While the write time of 512 bytes is 200 μsec, the data erase time per 16 KB takes about 2 msec. Therefore, the data erase time occupies most of the time actually required for writing. In order to solve this problem, Sp that manages unused areas where data has not been erased
Manage ace Bitmap and unused area after data erase
Space Bitmap is used to manage the area. By separately managing the unused area according to the presence or absence of data, it is possible to erase data in advance using the free time, and high-speed writing of data can be realized.

As described above, it is faster to write data in 16 KB units at a time than to write data having a small size a plurality of times, so that the sector size for the management area (512 bytes) can be reduced. Separately, a cluster of a large size (16 KB) is prepared for writing, and each space bitmap is used to manage the area.

Space Bitmap for managing the above two areas
Is schematically shown in FIG. As shown in this figure, Unallocated is used to manage the presence or absence of data in the unused area.
Using the Space Bitmap 611 and the Freed Space Bitmap 614, an Unallocated Space Bitmap 611 and a Fragment Space
Bitmap 615 is used. Unallocated Space Bitma
The p631 manages an unused area where data has been erased, and the size corresponding to 1 bit is 16 KB. Freed
Space Bitmap 634 manages an area that is not used but data is not erased, and the size corresponding to 1 bit is 16 KB.
It is. The Fragment Space Bitmap 635 manages an area of file management information such as File Entry, and the size corresponding to 1 bit is 512 bytes.

FIG. 7 shows an Unallocated Space Bitmap 631,
The structure of the Freed Space Bitmap 634 is shown. These have the same configuration, and UDF's Space Bitmap Descriptor
Has become an extension. The Descriptor Tag 701 field is a tag for identifying this Descriptor. Number of Bi
ts 702 is the number of bits in the bitmap, and indicates the total number of clusters in the area to be managed. Number of Bytes 703 indicates the number of bytes used in the bitmap. Up to here UD
Same as F's Space Bitmap Descriptor. Allocatio
The n Starting Position 704 indicates a starting cluster number when searching for a free area when an allocation request (or an initialization request) occurs. This numerical value stores the number of the cluster to which the last assignment was made, and the next assignment is the first free area found by searching from the continuation. By managing in this way, the allocated clusters are distributed over the entire Partition and the number of times of writing is equalized, so that the life of the media card can be extended.

FIG. 8 shows the configuration of the Fragment Space Bitmap 635. Descriptor Tag 801 field is this Desc
This tag identifies the riptor. The Bitmap Size 802 field is the number of sectors in one cluster, and is the number of bits in one bitmap. In the case of a semiconductor player, the sector size is 512 bytes and the cluster size is 16 KB.
Bitmap Size is 32. The Number of Bitmaps 803 field is the number of bitmaps stored in this Descriptor. This is the header area of the Descriptor. In the following areas, Fragment Position 804 and B
There are one or more combinations of itmap 805, and a plurality of combinations exist depending on the situation. Fragment Position 804 is Bitmap 805
This indicates where the area indicated by is starting from. The logical sector number of the first sector of the Bitmap 805 is stored. Bitmap 805 is a bitmap that actually performs area management, and has a bit number of Bitmap Size 802. This Fragment Space Bitmap 635
While Bitmap 631 performs area management in units of 16 KB, it performs area management in units of 512 bytes.

Next, referring to the flowchart of FIG.
The assignment relationship between two Space Bitmaps will be described. 1. When writing file data, use Unallocated Sp
Allocate from ace Bitmap (S901) 2. If there is no free space in Unallocated Space Bitmap,
If there is free time, the data is initialized from the Freed Space Bitmap to create a free space (S902) 3. If the data of the file is deleted, the freed space bitmap manages the freed space (S903) 4 When creating file management information such as File Entry, allocation is performed from the Fragment Space Bitmap (S9).
04) 5. If there is no free space in the Fragment Space Bitmap, Un
Allocate from allocated space Bitmap. Unalloca
If there is no free space in the ted Space Bitmap, the Freed Sp
Initialize data from ace Bitmap and assign (S
905) 6. When deleting file management information such as File Entry, the vacant area is managed by the Fragment Space Bitmap (S906). Merge into one cluster, Freed Space
Manage as a free area of Bitmap. (S907) Next, the Fragment Space Bitmap will be described in detail with reference to FIG. 1. Fragment Space Bitmap is Unallocated Space Bitmap
To allocate an area of 16 KB, and allocate that area to 5 KB.
Allocate 12 bytes at a time for management information (S1001) 2. When all the currently held areas are allocated to management information, the Space Bitmap information becomes unnecessary, so that it is deleted and a new 16 KB is allocated from the Unallocated Space Bitmap ( S1002) 3. If the management area is released, change the Space Bitmap if it currently has a Space Bitmap (S1003) 4. If it does not have a Space Bitmap above, a new Spac
e Create a Bitmap (S1004) 5. The area is discretely released and multiple Fragment Space Bits are created.
If it becomes necessary to hold the map, the File Entry of file1 held by SB2 and the File Entry of file2 held by SB3
Copy the entry to the free space of SB1. Next, SB2 and SB3 in which all areas are empty are released to the Freed Space Bitmap. As a result, the data held is only SB1, and the data amount can be reduced. (S1005) As an example of area management, FIG. 11 shows an area allocation method at the time of file creation. 1. Allocate one sector (512 bytes) from the Fragment Space Bitmap to an area for File Entry to create a File Entry describing file information (S1101) 2. If there is no area to be allocated to the Fragment Space Bitmap, Unallocated Space Bitmap to Fragment S
One cluster (16 KB) is allocated for pace (S110)
2) 3. If there is no allocated area in the Unallocated Space Bitmap, Fragment Space
One cluster (16 KB) is initialized and allocated (S
1103) 4. If there is no allocated space in the Freed Space Bitmap, the medium is full and a new file cannot be created (S1104) 5. File Entry is created (S1105) 6. File Unallocated Sp data area (16 KB)
Allocate from ace Bitmap (S1106) 7. If there is no area to be allocated to Unallocated Space Bitmap, initialize and allocate necessary area from Freed Space Bitmap (S1107) 8. There is no area to be allocated to Freed Space Bitmap above In this case, since there is no area for writing more data, the operation of writing data to the file ends (S1108). About correspondence table of physical address and logical address>
In a media card, data cannot be written to all physically existing data spaces, but can be written only to an area called a logical sector. Logical addresses, which are addresses of logical sectors, do not always exist physically side by side. This is because the correspondence between the logical address and the physical address is rewritten when a space in which a part of the medium is damaged and reading and writing cannot be performed is replaced with another alternative space. That is, in the media card, the physically discontinuous area is made to appear as a logically continuous sector by rewriting the correspondence table between the physical address and the logical address.

On the other hand, in this file system, Allocation Descriptor is used to indicate the file allocation area.
You are using r. In this Allocation Descriptor, the area is represented by a combination of the allocation start position and the allocation size.If the allocation area is discrete, the number of Allocation Descriptors that describe it increases, and the overhead of file management information increases. Will increase. Therefore, it is necessary that the allocated area be a continuous area as much as possible.

As a method of solving this problem, there is a method of rewriting a correspondence table between physical addresses and logical addresses. FIG. 12 shows an example of rewriting the correspondence table. In this example,
The data of file1 exists at physical addresses 0 and 2, and the data of file2 exists at physical address 1. In the correspondence table 1201, since the physical address 1203 and the logical address 1202 have the same value, the data of file2 is also sandwiched between the data of file1 on the logical address. Therefore, when the correspondence table is rewritten, the data position does not change at the physical address 1213, but the data is continuous at the logical address 1212. In this way, one Allocation Des
It is possible to express the area with criptor.

In the above-described file system, the method of using the Space Bitmap as the area management has been described. Space Bi
The advantage of tmap is that the size is fixed length in proportion to the size of the area to be managed, but on the contrary, when the area to be managed becomes large, a large Bitmap is required. On the other hand, the Space Table can be efficiently managed when the area to be managed is continuous, and the management information increases when the area is discrete. Therefore, when the management area is made continuous using the above method, the management can be performed more efficiently by using the Space Table.

<7. AV Attributes> Next, the operation of a file when editing a digital work will be described. When editing a file such as a character, a part of the file is changed, overwritten or added, and written to a media card. However, for music data and video data, the size to edit such as when recording is undecided,
You do not edit the file directly. For example MD
In the case of (MiniDisc), a new file (= track) is first created for recording. After that, when connecting music to one music, the newly created file is combined with another file to make one file. When dividing between music, an operation of dividing one file into two files is performed. As described above, the music data has different properties from the character data, and thus the editing operation method as a file is greatly different.

Therefore, whether the file system needs to split or combine the file in advance and music data that does not need to be overwritten or added, or character data that does not need to be split and combined but needs to be overwritten or added As a method of this determination, information indicating the AV attribute is inserted in the File Entry for music data and moving image data files, and the AV attribute information is not inserted for the other character data. A of File Entry of file
The determination can be made by referring to the V attribute. As a result, the file system does not need to prepare all functions such as division, combination, overwriting, and appending as functions for the file, and only needs to prepare the necessary minimum functions depending on whether the data is music data or character data. In other words, when a portable recording / reproducing apparatus is considered, the amount of memory can be reduced as compared with preparing all functions.

As described above, the data structure of the digital work recording medium according to the present invention and the file system of the device for accessing the recording medium have been described based on the embodiments. However, the present invention is not limited to these embodiments. Of course, it is not limited. That is, (1) the digital work medium is a media card using a flash memory, but any other nonvolatile memory such as a bubble memory may be used as long as it is a nonvolatile memory. (2) Although the erase size of the flash memory is 16 KB and the sector size is 512 bytes, the present invention is not limited to this size. (3) UDF was extended as a file system.
The content of the present invention may be extended using TFS or a unique file system. (4) The Volume Structure is placed at the beginning and end of the media card, but may be anywhere within the media card. (5) Although the AV attribute is described in the File Entry of the file system, the location of the AV attribute may be a UDF extended attribute, or the application may notify the file system of the AV attribute in advance.

[0041]

As is clear from the above description, the digital copyrighted work recording medium according to the present invention writes data to the flash memory with a size equal to or larger than the erase size, so that writing can be performed at high speed. By performing the erasing process in advance, high-speed writing can be performed without erasing data.

Further, the block area for managing the file arrangement information can be minimized by continuously assigning the logical block and the physical block in the media card by changing the correspondence.

Also, by providing the AV attribute, the minimum necessary functions of the file system can be implemented, so that the memory saving which is essential for a portable type can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing an operation of saving data in a media card according to an embodiment of the present invention;

FIG. 2 is a configuration diagram of a UDF according to an embodiment of the present invention.

FIG. 3 shows a file structure according to an embodiment of the present invention.
Configuration diagram

FIG. 4 is a configuration diagram of a volume format according to an embodiment of the present invention;

FIG. 5 is a configuration diagram of a management area of a UDF according to the embodiment of the present invention;

FIG. 6 is a configuration diagram of a Space Bitmap according to an embodiment of the present invention.

FIG. 7 shows an Unallocated Sp in one embodiment of the present invention.
Configuration diagram of ace Bitmap and Freed Space Bitmap

FIG. 8 shows a Fragment Space in one embodiment of the present invention.
Configuration diagram of Bitmap

FIG. 9 is a flowchart of an operation of allocating between Space Bitmaps according to an embodiment of the present invention.

FIG. 10 shows a Fragment Spa according to an embodiment of the present invention.
ce Bitmap allocation operation flow chart

FIG. 11 is a flowchart of an area allocation operation at the time of file creation in one embodiment of the present invention.

FIG. 12 is a diagram illustrating an operation of changing a logical block and a physical block in a media card according to an embodiment of the present invention.

[Explanation of symbols]

200, 202, 400, 440, 500, 540 Volume structure (VolumeStructure) 201, 300, 420, 520 File structure (File
Structure 301, 421 File Set Descri
ptor) 302,422 Terminating Descriptor 303 Space Bitmap Descriptor
ptor) 304 File Entry (root)
) 305 Root directory data
(root)) 306 File Entry (File Entry (fil
e1)) 307 File 1 data (Data (file1)) 308 File 2 file entry (File Entry (fil
e2)) 309 Data of file 2 (Data (file2)) 320 File identification descriptor of parent directory (File Id
entifier Descriptor (parent)) 321 File Identifier of File 1 (File Identif
ier Descriptor (file1)) 322 File Identifier Descriptor (File Identif
ier Descriptor (file2)) 423 Space Bitmap 424 Reserved 501 Partition Descriptor 502 Partition Contents Use 503 Header (Unallocated Space Bitmap) 504 Bitmap (Unallocated Space Bitmap) ) 510,610 Unallocated space table (Unallocated S)
pace Table) 511, 611, 631 Unallocated space bitmap (U
nallocated Space Bitmap) 512,612 Partition Integri Table
ty Table) 513,613 Allocable space table (Freed Space
Table) 514, 614, 634 Allocatable space bitmap
(Freed Space Bitmap) 515,616 Reserved 615,635 Fragment space bitmap (Fragm
ent Space Bitmap) 701, 801 Descriptor Tag 702 Number of Bits 703 Number of Bytes 704 Allocation Starting Positio
n) 705, 805 Bitmap 802 Bitmap size (Bitmap Size) 803 Number of bitmaps (Number of Bitmaps) 804 Fragment Position 1201, 1211 Correspondence table 1202, 1212 Logical block 1203, 1213 Physical block

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Nobuyuki Eno 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Junichiro Soeda 1006 Kadoma Kadoma Kadoma City, Osaka Prefecture F inside Matsushita Electric Industrial Co., Ltd. Terms (reference) 5B035 AA00 BB09 BC05 CA29 5B058 CA26 KA33 YA20 5B060 AA02 AA06 AB26 AC11 5B082 AA11 AA13 DE04 EA01

Claims (9)

[Claims] 1. A logical block of a file system which handles digital copyrighted work data as a file, and a data area of the file has an A size equal to the erase size of the nonvolatile memory.
A file system having two types of logical block structures, a V block, a file entry for managing file names and file attributes, and a management information area for managing free areas of all blocks, a management block having the same size as a sector size. 2. A file system that handles digital copyrighted work data as a file manages a logical block in a nonvolatile memory as a free list of blocks that need to be erased for writing, and the logical block has already been erased. A file system with a structure that manages blocks as an erased free list. 3. By assigning an AV attribute to a file of digital copyrighted work data to be divided / combined, in the case of the AV attribute, the division / combination processing unit operates, and the additional recording / overwrite processing unit is disabled. A file system having an AV attribute determination function to perform 4. A file system having a function of changing the correspondence between a logical block and a physical block in a nonvolatile memory and continuously assigning the logical block arrangement of a file. 5. The file system according to claim 1, further comprising a function of allocating the data of the management block from the AV block and, if there is a vacancy in the management block, performing continuous allocation as the AV block. . 6. A file system including two or more copies of a volume management area for managing all logical blocks in a nonvolatile memory. 7. The file system according to claim 6, wherein an identification number is provided in the volume management area and a copy of the volume management area. 8. The file system according to claim 7, wherein the volume management area is an integral multiple of an erase size of the nonvolatile memory. 9. The file system according to claim 1, wherein the nonvolatile memory has an active element for performing mutual authentication with a device that accesses the nonvolatile memory. .