JPH0546456A - Access system for read after write type storage medium - Google Patents

Abstract

PURPOSE:To correct and update data stored in a read after write type storage area and to easily manage updated data by sequentially writing updated data in a searched unwritten area and reading out data from a searched written area. CONSTITUTION:The unwritten area following the written area where data is written last out of data storage areas of the read after write type storage medium is searched by a write means of a CPU, and updated data is sequentially written in the searched unwritten area. After this write, the written area where data is written last out of data storage areas is searched by a read means of the CPU 11 to read out data from the searched written area. Consequently, the latest updated data is read when data is read out from data storage areas. Thus, data stored in the read after write type storage medium is corrected and updated by an operator, an the updated data of the read after write type storage medium is easily managed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a write-once type storage medium access system in which storage data cannot be physically modified or updated and is additionally written in a storage area.

[0002]

2. Description of the Related Art Generally, a storage medium such as a hard disk (HD) or floppy disk (FD) is, by its nature, accessed at the same storage location by accessing storage data as shown in FIG. It is easy to physically correct and update. On the other hand, storage media such as optical discs (OD)
The so-called destructive writing method is adopted, and by its nature, data cannot be physically corrected or updated at the same storage location. If correction or update is attempted in this way, a write error will occur.

Therefore, in the conventional write-once type storage medium access method, when the storage data is modified or updated, the update data is updated.
When the updated data is read by writing the management table in another unwritten area and additionally writing the management table, the operator reads the management table on the display screen of the CRT, for example. It is configured to select update data.

[0004]

However, in the above-mentioned conventional write-once type storage medium access method, the update data is not updated.
When reading the data, the operator reads the management table on the display screen of the CRT and selects the latest update data, so that the operator can correct and update the stored data. In addition, there is a problem that it is difficult to manage modification data and update data.

The present invention has been made in view of the above-mentioned conventional problems, and allows an operator to correct and update the storage data of a write-once type storage medium, and to correct the write-once type storage medium. An object of the present invention is to provide an access method of a write-once type storage medium that can easily manage data and update data.

[0006]

In order to achieve the above-mentioned object, the access method for the write-once type storage medium of the first invention of the present application,
Writing means for searching for an unwritten area next to the written area where the data has been written last among the data storage areas of the write-once type storage medium, and writing update data to the searched unwritten area; It is characterized in that it further comprises a reading means for searching a written area where the data is written last in the data storage area and reading the data from the searched written area.

In order to achieve the above-mentioned object, the write-once type storage medium access method of the second invention of the present application is such that, in the above-mentioned first invention, the writing means updates the data in the data storage area.
The data is written together with the management data for the updated data, and the reading means searches for a written area in which the data is finally written based on the written management data. ..

In order to achieve the above-mentioned object, the write method of the write-once type storage medium according to the third aspect of the present invention, in the above-mentioned first or second aspect of the invention, the writing means is the data written in the data storage area. It is characterized in that an unwritten area is searched for by reading the data by DMA transfer.

In order to achieve the above-mentioned object, the write system of the fourth invention of the present application achieves the above-mentioned object. It is characterized in that it is allocated as a data storage area, and update data is written together with a management table including information indicating at least the position of the allocated area.

In order to achieve the above-mentioned object, the write-once type storage medium access method of the fifth invention of the present application is, in the above-mentioned fourth invention, the writing means writes data according to a free area when writing the update data. -Change the storage area allocation,
It is characterized in that a new management table corresponding to the allocation of the changed area is additionally written together with the update data.

In order to achieve the above-mentioned object, the write method of the write-once type storage medium of the sixth invention of the present application, in the above-mentioned first to fifth inventions, the writing means writes the first data to be updated. As a reference, the second data indicating only the portion to be changed / corrected is written in the unwritten area together with the management table indicating the contents of the change / correction, and the reading means is
It is characterized in that the first data, the second data, and the management table are read and expanded into the latest update data.

In order to achieve the above-mentioned object, the access system of the write-once type storage medium of the seventh invention of the present application is the last written one of a plurality of blocks of the first data storage area of the write-once type storage medium. If the data obtained by adding the additional data to the data of one block does not reach the block, the data obtained by the addition is added to the next block of the first block. When the data obtained by writing to the second block reaches the block, the data corresponding to the block is written to the second data storage area of the write-once type storage medium. Writing means for writing the data in excess of the block into the second block;
The data written in the first data storage area, the data is read from the last written block in the first data storage area, and the first and second data storage areas are read. The latest data is obtained by combining the data read from the area.
And a reading means for taking out as a data.

[0013]

According to the first aspect of the invention, the writing means searches for an unwritten area next to the last written area in which data has been written in the data storage area of the write-once type storage medium. Update data is sequentially written in the write area. Further, after the data is written in this way, the reading means searches for the last written area in the data storage area in which the data has been written, and reads the data from the found written area. Therefore, when reading the data from the data storage area, the latest updated data can be read. Therefore, the operator can correct and update the storage data of the write-once storage medium, and can easily manage the update data of the write-once storage medium.

According to the second invention, by the writing means,
The update data is written in the data storage area together with the management data for the update data. Further, after the data is written in this way, the reading means searches for the written area in which the data is written last based on the written management data. Therefore, for example, even when the capacity of the update data exceeds the minimum unit (block), the operator can correct and update the storage data of the write-once storage medium, and the write-once storage medium can be updated. The update data can be easily managed.

According to the third invention, by the writing means,
By reading the data written in the data storage area by DMA transfer, the unwritten area can be searched for at high speed, and thus the updated data can be written at high speed.

According to the fourth invention, by the writing means,
Any free area of the write-once type storage medium is allocated as a data storage area, and update data is written together with a management table containing at least information indicating the allocated area. Therefore, the data storage areas can be allocated according to the operator's preference, and the data storage areas of the write-once type storage medium can be effectively used.

According to a fifth aspect of the present invention, in the above-mentioned fourth aspect of the invention, when the update data is written by the writing means, the allocation of the data storage area is changed in accordance with the empty area, and the update data is stored together with the update data. Since a new management table corresponding to the allocation of the changed area is added, it is possible to change the allocation of the data storage area once set as necessary. The data storage area of the type storage medium can be used more effectively.

According to the sixth aspect of the invention, by the writing means,
The second data indicating only the portion to be changed / modified based on the first data to be updated is written in the unwritten area together with the management table indicating the contents of the change / correction.
Further, after the data is written in this way, the reading means reads the first data, the second data, and the management table and expands them into the latest update data. Therefore, the portion of the first data to be updated that does not need to be changed or modified is used as a part of the latest data even after the update, and as a result, the write-once type The data storage area of the storage medium can be effectively used.

According to the seventh invention, by the writing means,
In the case where the data obtained by adding the additional data to the data of the first block written last among the plurality of blocks of the first data storage area does not fill the block. Writes the data obtained by the addition to the second block next to the first block. On the other hand, when the additionally obtained data reaches the block, the data satisfying the block is written in the second data storage area of the write-once type storage medium and the block is also written. Is written in the second block of the first data storage area. Also, after being written like this,
The reading means reads the data written in the second data storage area, reads the data from the last written second block in the first data storage area, and reads the data. The data read from the first and second data storage areas are combined and taken out as the latest data. Therefore, the read time can be shortened, and the data storage area of the write-once type storage medium can be used more effectively while improving the read efficiency.

From the following examples of the present invention, such effects of the present invention will be more apparent, and further effects of the present invention will be apparent.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a block diagram showing an embodiment of an access device for a write-once storage medium according to the present invention, FIG. 2 is an explanatory diagram showing a storage area of an optical disk of the storage device of FIG. 1, and FIG. FIG. 4 is a flow chart for explaining the operation of the access device for the write-once type storage medium of FIG. 1, showing the address of the storage area.

In FIG. 1, a CPU (Central Processing Unit) 11
Processes the data and commands input via the keyboard 12, and controls the display of the CRT 13 and the writing and reading of the memory 15 via the control circuit 14. The CPU 11 also processes data read by the scanner 17 via the I / F (interface) circuit 16, controls writing and reading of the write-once type storage device 18, and controls the printer 19. Control printing. The memory 15 is, for example, a RAM
(Random access memory), storage device
The numeral 18 is composed of, for example, an optical disk (OD) and its drive device.

The storage area of each file F of the optical disk of the storage device 18 is configured for each block B1 of the minimum unit of 512 bytes or 1024 bytes, for example. -Data is stored. The capacities of the blocks B1 to B1 are different for each storage medium.

First, the CPU 11 responds to the data and commands input via the keyboard 12 by the respective data files F.
The position and size of the area for storing are fixed and allocated. In this case, when there are a plurality of files F to be handled, allocation is performed for that, and the size is determined in consideration of the expected number of updates.

When the data is stored in the optical disk, it is stored from the first block B1 of the area of the file F, and when updating the stored data, the CPU 11
First, the stored data is read from the optical disk to the memory 15 and displayed on the screen of the CRT 13, and is corrected on the memory 15 according to the data and commands input via the keyboard 12.
Then, when registering this update data in the optical disc,
As shown in FIG. 2, the data is transferred from the memory 15 to the optical disk and is finally written in the data storage area (data allocation area) which constitutes the file F out of all the data storage areas 101 of the optical disk. Register the block Bn + 1 next to the block Bn. In this way, when the data is updated on the file F, the written area F1 becomes large and the unwritten area F2 becomes small.

Next, the detailed operation of the update process and the update data read process will be described with reference to FIGS.
In FIG. 3, T is the start address of the file F,
Y is the last address of the written area F1 of the file F, and X is the start address of the unwritten area F2 of the file F.

In the case of the updating process, first, the address T indicating the position of the first block B1 of the file F is set to the read address n (step S1 in FIG. 4), and the data of the read address n is read from the optical disk. Store in memory 15 (step S2). Next, it is determined whether or not the area of the read address n is in the unwritten state (area F2) (step S3), and if it is not in the written state, the read address n is incremented (step S4) and step S2.
Then, the area F2 in the unwritten state is searched. In step S4, it is preferable to check the size of the data area of the file F.

When the area F2 in the unwritten state is obtained, the process branches from step S3 to step S5, the read address n is set to the write address X of the update data, and then the read address n is the first of the above-mentioned storage data. Address T
It is determined whether or not it is larger (step S6). When n> T, the read address n is decremented by 1 (step S7), the read address n is set to the last address Y of the stored data (step S8), and then the start address X of the unwritten area F2. The update data is stored in the area of. Incidentally, in step S7, it is preferable to check the storage data in consideration of the write error.

In step S6, if n≤T, the optical disc is in a completely unwritten state, so step S9
Then, the last address Y of the stored data is set to the address "0" and the data is stored in the area of the write address X.

When reading the updated data, the data is sequentially read from the area of the write address T to search the unwritten area F2 next to the latest updated data,
The data of the written area F1 before this unwritten area F2
Area that has been written by determining whether the data is valid
Read the latest update data of F1.

Therefore, according to the above embodiment, the CPU 11 reads the data written on the optical disk, searches the unwritten area F2 next to the written area F1, and updates the unwritten area F2. -Since the data is sequentially written and the latest update data is read by searching the write area F1 of the latest update data written in the data area of the optical disk, the write-once storage medium for the operator It is possible to correct and update the storage data of the above, and it is possible to easily manage the correction data and the update data of the optical disk. In this case also, the history of update data can be managed, which is convenient.

In the above embodiment, when the area of the update data is obtained, the search is performed from the write address at the head of the file F (steps S1 to S4), but at the end of the file F. The search may be performed from the write address.

In the above embodiment, a non-rewritable storage medium such as an optical disk has been described as an example.
When applied to a rewritable storage medium such as a hard disk, the update data can be sequentially added without erasing the storage data. Therefore, the update data can be added depending on the nature of the data. It is possible to manage the history of
The safety of the computer can be secured. In this case, if the flag indicating the unwritten state is set in a predetermined area of each block of the storage medium, the unwritten area is supported.
It is possible to simplify the processing for switching.

Next, referring to FIGS. 5 to 7, the second embodiment of the present invention will be described.
An example will be described. FIG. 5 is an explanatory view showing a storage area of an optical disc in a second embodiment of the write-once storage medium access device according to the present invention, FIG. 6 is an explanatory view showing addresses of the storage area of FIG. 5, and FIG. 3 is a flowchart for explaining the operation of the access device for the write-once type storage medium of the second embodiment. In the first embodiment, one block B1 ...
Since one data is written to each block, 1 block B1
It is not possible to write data with a capacity exceeding ~,
This embodiment is constructed so that data D having a capacity exceeding one block B1 can be processed.

As shown in FIG. 6 (A), the storage area of each file F of the optical disk of this embodiment is, for example, the smallest unit block B1 of 512 bytes or 1024 bytes as in the first embodiment. Although configured, when the write data D has a capacity of a plurality of blocks B1 to B1, the blocks B1 to B1 are continuously written, and at the end of the write data D, the data size and start position (pointer S ) Etc., the management data of the data is written. In addition, update data
Since the general operation of writing the data D is the same as that of the first embodiment, its detailed description will be omitted.

Next, the operation for reading the update data D will be described with reference to FIGS. 6 (A) and 7. First, FIG.
In step S11 shown in step S12, the storage data is sequentially read for each block B1 to be stored in the memory 15, and the subsequent step S12
, The data of the last management data (address Y)
Search the data size and pointer S,
The pointer S reads all the latest data D.

Therefore, in this embodiment, if the write data D has a capacity of a plurality of blocks B1 ...
Since the management data including the data size, the start position (pointer S), etc. is written at the end of the write data D at the same time as B1 to B1, the data D having a capacity exceeding one block B1 to B1 is written. Can be processed.

As shown in FIG. 6B, in an actual system, in order to deal with an error, etc., a pointer indicating the next block of valid data is included in the start block of data. Is preferred.

Next, a third embodiment will be described with reference to FIGS. FIG. 8 is an explanatory diagram showing DMA (direct memory access) transfer in the third embodiment of the write-once type storage medium access device according to the present invention, and FIG. 9 is a diagram for explaining the operation of the third embodiment. It is a flow chart.
In the second embodiment, since all the storage data in the written area F1 is read into the memory 15 and the head address of the unwritten area F2 is searched, the ready check time, seek time, etc. Although the processing time of the CPU 11 becomes long, the processing time of the CPU 11 is shortened by adding a DMA controller in this embodiment.

First, as shown in FIG. 8, a buffer area (capacity M) of the memory 15 for storing the storage data of the optical disk is secured. It is desirable that the buffer area has a size capable of storing all the data in the allocation area of the optical disk, but if the capacity of the system is limited, the buffer area should be as large as possible.

Then, in FIG. 9, the start block position T (n ← T) of the file F and (step S21), the read data amount H (h ← H) of the file F and (step S22)
), And the buffer capacity M (m ← M) of the memory 15 is set (step S23). Next, when the set buffer capacity m is larger than the read data amount h, the read data amount h is set to the buffer capacity m (step S2
4, S25), D so that all data of the file F is DMA transferred from the optical disk to the buffer area of the memory 15.
The MA controller is controlled (step S26).

Therefore, during this read time, the CPU 11
Can perform other processing. This step
In S26, the DMA controller determines the current read processing block amount a (≤m) and the last read position (error).
When the error occurs, the error occurrence position) b is returned to the CPU 11 as the status.

If all the data is read without causing an error, there is no unwritten block in the allocation area of the file F.
On the other hand, when an error occurs, the data in the unwritten area F2 may be read or the data in the written area F1 may be read.
It can be judged by the status. Therefore, in the former case, the block in which the error has occurred is the head block of the unwritten area F2, and in the latter case, the unwritten area F2 can be reached by further reading the data. it can.

In FIG. 9, if an error occurs, the process proceeds from step S27 to step S28 and the unwritten position
Whether it is F2 or not is determined. If it is not the unwritten position F2, the process proceeds to step S29, where the current read processing block amount a is set as the buffer capacity m of the memory 15 and step S3 is performed.
Go to 0. If no error occurs, step S2
Proceed directly from step 7 to step S30.

In step S30, the read data amount h is set to the remaining read amount (= hm), and step S2
Return to 3 and read the remaining data. Incidentally, step S30
, The read data amount h is the remaining read amount (h
If it is smaller than -m), the unwritten position F2 does not exist in the optical disc, so that the update data cannot be written. Further, in step S28, in the case of the unwritten position F2, the error occurrence position is the start position of the unwritten area F2 as described above, so the error occurrence position b is set to the head write position of the update data. Set to (step
S31).

Therefore, according to the above embodiment, since the storage data is transferred from the optical disk to the memory 15 by the DMA controller, the write position at the beginning of the update data can be reached in a short time. Yes, ready check time and
The processing time can be shortened by omitting the processing time.
Further, the processing efficiency can be improved even when the amount of storage data is small, and further, the CPU 11 can execute other processing during the DMA transfer.

Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 10 (A) is an explanatory view showing the storage area of the optical disc in the first to third embodiments, FIG. 10 (B).
FIG. 14 is an explanatory diagram showing a storage area of an optical disc in the fourth embodiment.

As shown in FIG. 10A, in the first to third embodiments, since the storage area of the optical disk is fixedly allocated for each file F, the storage area is filled with the update data. Then, new update data cannot be written. Therefore, if there is a file that is frequently updated depending on the user, the update data cannot be written even though there is a free area.

Therefore, in the present embodiment, in such a case, the update data can be written by effectively utilizing the free area. As shown in FIG. 10 (B), a management table 20 of an appropriate size is secured from the first block at the beginning of the storage area.
20 is composed of the start block position and size (or end block position) of each file F. Although this management table 20 can be changed as described later,
In FIG. 10 (B), they are fixed and allocated.

The data area of each file F is sequentially secured in an area following the management table 20 with an appropriate size (minimum size normally used + α), and an unused spare area 21 is secured in the rear area. To be done. Then, as shown in the first to third embodiments, the update data is additionally written in the area of the file F, and when the area of the file F becomes full, new update data is written in the spare area 21, The management table 20 is updated and added.

Therefore, according to the present embodiment, since the update data is written in the spare area 21 of the optical disk, it is possible to write the update data when there is a file that is frequently updated according to the user. it can. In this embodiment, the spare area
Although the update data is written in 21, the update data may be written in the free area F2 of another file in which update is not frequently generated.

Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG. 11 is an explanatory diagram showing a storage area of the optical disc in the fifth embodiment. In the fourth embodiment, the data area of each file is secured by being fixed sequentially, but in this embodiment, the data area of each file A and B is not fixed and update data is secured. Regardless of the files A and B, they are additionally written and managed by the management table 20.

As indicated by 20a in FIG. 11, an area of an appropriate size is reserved for the management table 20 from the first block of the optical disk, and the data areas of the files A and B follow this area. It is secured without being fixed. The management table 20 is written with initial values "0" of the start block position and size (or end block position) of each of the files A and B. Then, as shown in 20b, each data of the files A and B is added to the data area to update the management table 20, and the updated data of the files A and B is shown in 20c. Then, the management table 20 is updated by being additionally written in the data area in the order of update.

That is, in the fourth embodiment, since the data area of each file F is fixed and secured sequentially, a useless data area is generated. However, in the fifth embodiment, the update is performed. Since the data is additionally written regardless of the files A and B, the data area of the optical disk can be effectively utilized, and the unwritten position F2 can be reached at high speed by the management table 20. You can If the power is turned off while the update data is being written, the management table 20 is not destroyed and the update data can be written again.

Next, referring to FIGS. 12 to 14, the sixth embodiment of the present invention will be described.
An example will be described. FIG. 12 is an explanatory diagram showing the updating process of the first to fifth embodiments, FIG. 13 is an explanatory diagram showing the updating process of the sixth embodiment, and FIG. 14 is an updating process of the sixth embodiment. FIG. 6 is an explanatory diagram showing a data read process. In the first to fifth embodiments described above, as shown in FIG.
However, in the present embodiment, the
As shown in 13, the data a is modified into the data b,
When the data x is modified to the data y, only the modification data b and y are additionally written in the update area F3, and the modification information dedicated management data only of the modification data b and y are additionally recorded. Is configured.

When the update data is read, the management table and the management information dedicated to the change information are used, and as shown in FIG. If there is a shortage, the storage data is read out to a storage medium that can be physically modified and updated, such as a hard disk, and the latest data can be read by the change information dedicated management data.
Deploy to the data. Therefore, according to this embodiment, since only the correction data b and y are additionally written without additionally writing all the update data of the file A, the data area of the optical disk can be used more effectively.

Next, referring to FIGS. 15 to 19, the seventh embodiment of the present invention will be described.
An example will be described. 15 is an explanatory diagram showing a general write process, FIG. 16 is an explanatory diagram showing a read process of the update data written by the process of FIG. 15, and FIG. 17 is another general write process. 19 is an explanatory diagram showing the storage area of the optical disc in the seventh embodiment, and FIG.
FIG. 19 is an explanatory diagram showing a writing process in the seventh embodiment.

In a general write process, normally, as shown in FIG. 15, when writing data a to d in blocks B1 to B4, an empty area is generated in each block B1 to B4, and Even when additional data e is additionally written, an empty area is generated in the block B5. And such data a to e
When reading the data into the memory 15, as shown in FIG.
The empty areas of the blocks B1 to B5 are taken into consideration by the management table and the data a to e are read so as to be sequential in a packed state.

In another general write process, as shown in FIG. 17, when the data s and t are written in one block B1 and the next data u is written in the next block B2,
When an empty area occurs in the block B2 of the data u, and when the additional data w is written, all the update data s to w
Is added to the following blocks B3 and B4. When such data s to w are read into the memory 15, the update data s to w additionally written in the blocks B3 and B4 are read.

In the writing method as shown in FIG. 15, it takes time to read because the empty areas of the blocks B1 to B5 are taken into consideration when reading, and in the writing method as shown in FIG. -Tas ~ w block B3,
Although the storage area is wasted because it is additionally written in B4, in the seventh embodiment, as shown in FIG. 18, the temporary area F4 for temporarily storing the data and the normal data are stored in the temporary area F4. The normal area F5 for storing the data area is divided into two areas, and the reading time is shortened to effectively use the data area.

In FIG. 19, the data less than the block is
When writing the data a, an empty area is provided and written in the block B1 of the temporary area F4. When the data b whose total amount together with the data a is less than the block is written, an empty area is provided and the data a is written in the block B2 next to the temporary area F4.
Write b. When the total amount of data a and b exceeds the data block c (= data c'up to 1 block + remaining data c "), the data for the block -The blocks a, b, c'in the normal area F5
At the same time as writing to B1, the remaining excess data c ″ is written to the block B3 next to the temporary area F4 by providing an empty area.

Similarly, when writing the data d whose total amount with the data c ″ is less than the block, an empty area is provided and the data c ″ is written in the block B4 next to the temporary area F4. ,
Write d. When the total amount of the data c ″ and d exceeds the block, the data e (= data e ′ reaching up to 1 block + remaining data e ″) is to be written for the block. The data c ", d, and e'are written in the block B2 of the normal area F5, and the remaining excess data e" is provided in the empty area to provide a block B5 next to the temporary area F4.
Write in. When reading the write data a to e, the data a to d of the blocks B1 and B2 of the normal area F5,
e ′ and the data e ″ of the block B5 of the temporary area F4 are read.

That is, basically, when writing to the temporary area F4, data is added to the previous block and written,
Temporary area F4 is written to the full block and excess data is written to the next block of temporary area F4.
The block data is written in the normal area F5. Therefore, the data area can be effectively used, and when the latest data is read, the data in the regular area F5 having no free area is read, so that the reading time can be shortened. ..

In this embodiment, the temporary area F4 and the regular area F5 are not secured for each file, and like the fifth embodiment, the update data is additionally written regardless of the file and the management data is added. The data area can be effectively used if it is configured to be managed by the data. In this case, if the pointer indicating the latest write block position of each file is written in the block of the temporary area, the management becomes simple.

[0065]

As described in detail above, according to the first aspect of the present invention, the writing means is arranged next to the last written area in which the data is written in the data storage area of the write-once type storage medium. Unwritten area, the update data is sequentially written to the searched unwritten area, and the read means searches the written area in which the last data is written in the data storage area, and the searched writing Since the data is read from the reserved area, the operator can correct and update the storage data of the write-once type storage medium, and can easily manage the update data of the write-once type storage medium. ..

According to the second invention, by the writing means,
The update data is written in the data storage area together with the management data for the update data, and the writing means in which the data is finally written by the reading means based on the written management data. Since the completed area is searched, the operator can correct and update the storage data of the write-once type storage medium, and can easily manage the update data of the write-once type storage medium.

According to the third invention, by the writing means,
Since the data written in the data storage area is read by DMA transfer, the update data can be written at high speed.

According to the fourth invention, by the writing means,
Since any free area of the write-once type storage medium is allocated as a data storage area and the update data is written together with the management table containing the information indicating at least the position of the allocated area, the data of the write-once type storage medium is written. -The data storage area can be used effectively.

According to the fifth invention, in the above-mentioned fourth invention, the allocation of the data storage area is changed in accordance with the free area when the update data is written by the writing means, and the update data is stored together with the update data. Since the new management table corresponding to the allocation of the changed area is additionally written, the data storage area of the write-once type storage medium can be used more effectively.

According to the sixth aspect of the invention, by the writing means,
Write the second data indicating only the portion to be changed / modified based on the first data to be updated in the unwritten area together with the management table indicating the contents of the change / correction,
Since the reading means reads the first data, the second data, and the management table and expands them to the latest update data, the data storage area of the write-once storage medium can be effectively used.

According to the seventh invention, by the writing means,
If the data obtained by adding additional data to the data of the first block written at the end of the first data storage area reaches the block, the block is filled. Minute data is written to the second data storage area, and data exceeding the block is written to the second block of the first data storage area, and read by the reading means. The data written in the second data storage area is read out, and the data is read from the last written second block in the first data storage area, and the first and second data storage areas are read out. Since the data read out from the data storage area is combined and taken out as the latest data, the data storage area of the write-once type storage medium can be used more effectively while improving the reading efficiency.

As a result of the above, the operator can correct and update the storage data of the write-once type storage medium, and easily manage the correction data and update data of the write-once type storage medium. It is possible to realize a very convenient write-once type storage medium access method that can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an access device for a write-once storage medium according to the present invention.

FIG. 2 is an explanatory diagram showing a storage area of an optical disc of the storage device of FIG.

FIG. 3 is an explanatory diagram showing addresses of a storage area in FIG.

FIG. 4 is a flowchart for explaining the operation of the access device for the write-once type storage medium of FIG.

FIG. 5 is an explanatory diagram showing a storage area of an optical disc in the second embodiment of the write-once type storage medium access device according to the present invention.

FIG. 6 is an explanatory diagram showing addresses of a storage area in FIG.

FIG. 7 is a flowchart for explaining the operation of the write-once type storage medium access device of the second embodiment.

FIG. 8 is an explanatory diagram showing DMA (Direct Memory Access) transfer in a third embodiment of the write-once type storage medium access device according to the present invention.

FIG. 9 is a flowchart for explaining the operation of the third embodiment.

FIG. 10 is an explanatory diagram showing a fourth embodiment of the present invention.

FIG. 11 is an explanatory diagram showing a storage area of an optical disc according to a fifth embodiment.

FIG. 12 is an explanatory diagram showing update processing of the first to fifth embodiments.

FIG. 13 is an explanatory diagram illustrating update processing according to the sixth embodiment.

FIG. 14 is an explanatory diagram showing a read process of update data according to the sixth embodiment.

FIG. 15 is an explanatory diagram showing a general write process.

16 is an explanatory diagram showing a process of reading the update data written by the process of FIG.

FIG. 17 is an explanatory diagram showing another general writing process.

FIG. 18 is an explanatory diagram showing a storage area of an optical disc according to a seventh embodiment.

FIG. 19 is an explanatory diagram showing a writing process in the seventh embodiment.

FIG. 20 is an explanatory diagram showing update processing of a storage medium capable of physically modifying and changing the storage data.

[Explanation of symbols]

 11 CPU (central processing unit) 18 Storage device (optical disk)

Claims (7)

[Claims] 1. A search is made for an unwritten area next to the last written area in which the data has been written in the data storage area of the write-once type storage medium, and update data is placed in the searched unwritten area. Writing means for writing, and a reading means for reading the written area in which the data is written last in the data storage area and reading the data from the searched written area. Write-once type storage medium access method. 2. The writing means writes update data in the data storage area together with management data for the update data, and the reading means writes in the written management data. 2. The write-once type storage medium access method according to claim 1, wherein a write-completed area in which data is written last is searched for based on the above. 3. The write-once type according to claim 1, wherein the writing unit searches for the unwritten area by reading the data written in the data storage area by DMA transfer. Storage medium access method. 4. The writing means allocates an arbitrary free area of the write-once type storage medium as the data storage area, and updates the management table including information indicating at least the position of the allocated area. 4. The write-once type storage medium access method according to claim 1, wherein data is written. 5. The writing means changes the allocation of the data storage area in accordance with the empty area when writing the updated data, and allocates the area after the change together with the updated data. 5. A write-once type storage medium access method according to claim 4, wherein a new management table corresponding to the above is additionally written. 6. The management table showing the contents of the change / correction of the second data indicating only the portion to be changed / corrected on the basis of the first data to be updated. Along with writing into the unwritten area, the reading means reads the first data, the second data, and the management table and expands them into the latest update data. 5. The write-once type storage medium access method according to any one of 5 above. 7. A data obtained by adding additional data to the data of the last written first block of the plurality of blocks of the first data storage area of the write-once type storage medium. If the data does not fill the block, the data obtained by the addition is written in the second block next to the first block so that the data obtained by the addition can fill the block. In the case of reaching, the writing means for writing the data for filling the block in the second data storage area of the write-once type storage medium and writing the data for the data exceeding the block in the second block. Reading the data written in the second data storage area and reading the data from the last written block in the first data storage area. Data read from the second data storage area An access system for a write-once type storage medium, which comprises: