The present invention relates to a data managing method for a memory apparatus using an irreversibly write memory.
In a system that uses an electrically erasable memory, with a precondition that data stored therein is rewritten, for a process that correlates logical information and physical information, physical information corresponding to all logical information is required. In addition, as another precondition, a process that correlates logical information and physical information using a redundant portion peculiar to such an electrically erasable memory is required. Moreover, since such an electrically erasable memory has a verify function that verifies written data by itself, it is not necessary to externally verify data.
Unlike with an electrically erasable memory, an irreversibly write memory of which data can be written one time is known. This memory is called a write once type memory or OTP (One Time Programmable ROM). Normally, an irreversibly write memory is non-volatile. In other words, once data is written to an irreversibly write memory, the data cannot be erased. Thus, after the power of an irreversibly write memory is turned off, data stored therein is retained.
When a data managing method for an electrically erasable memory is applied for the forgoing irreversibly write memory, the irreversibly write memory may not be effectively controlled. In addition, a correlation table for logical information and physical information results in a decrease of the memory capacity that the user can use.
It is therefore desirable to provide a data managing method that can be suitably and effectively applied to an irreversibly writeable memory.
An aspect of the present invention is a data managing method for a removable memory apparatus using an irreversibly writeable memory, comprising causing the correlation between logical information and physical information to be fixed.
Another aspect of the present invention is a data managing method for a removable memory apparatus using an irreversibly writeable memory, comprising obtaining the correlation between logical information and physical information by a calculation.
According to these aspects of the present invention, since logical information and physical information are correlated fixedly or by a calculation, it is not necessary to retain physical information corresponding to all logical information. As a result, the storage capacity of the memory can be reduced.
Next, with reference to the accompanying drawings, an embodiment of the present invention will be described.
The memory apparatus 1 has a data processing portion 20 and a memory portion 50. The memory portion 50 is an irreversibly write memory that is called OTP and of which data can be written one time. The memory apparatus 1 is also a non-volatile semiconductor memory. In other words, data that has been written to the memory portion 50 cannot be erased. After the power of the memory apparatus 1 is turned off, the stored data is retained. In the memory portion 50, data is read and written in a predetermined data unit. The memory portion 50 has a boot area from which data is initially read by the host system when the memory is attached thereto. A variety of types of information such as attribute information are pre-recorded in the boot area.
The data processing portion 20 and the communicating portion 30 are connected through internal buses 21 and 32. Likewise, the data processing portion 20 and the memory portion 50 are connected through internal buses 22 and 51. The data processing portion 20 can access memory management information 10 through internal buses 13, 23, and 14. The memory management information 10 contains an unusable block correlation table 11 and mapping reference information 12.
A memory apparatus 1′ shown in
The host system 40 can write data to the memory portion 50, 56 of the memory apparatus 1, 1′ and read data therefrom. An example of the host system 40 is a personal computer. Another example of the host system 40 is a digital electronic camera. A photographed picture is written to the memory apparatus 1, 1′. In addition, a picture is read from the memory apparatus 1, 1′. Another example of the host system 40 is an audio recording/reproducing apparatus. In this case, compressed audio data is written to the memory apparatus 1, 1′. In addition, compressed audio data is read from the memory apparatus 1, 1′.
The unusable block correlation table 11 is created by the data processing portion 20. In the memory apparatus 1 shown in
In the memory apparatus 1′ shown in
Next, with reference to
When the determined result at step S3 represents that the physical block number Nphy matches the i-th unusable block, the flow advances to step S6. At step S6, an i-th substitute block is used instead of the physical block number Nphy. Thereafter, the process is completed. In contrast, when the determined result at step S5 represents that i is equal to or larger than (k−1), the flow advances to step S7. At step S7, the physical block number Nphy is not an unusable block, but a usable block. Thereafter, the process is completed.
When physical block numbers or logical information of the unusable block correlation table are sorted in the ascending order or descending order, the process that references the unusable block correlation table can be performed at high speed.
At step S11, a physical block number Nphy is designated as an object to be processed. At step S12, i is initialized. At step S13, it is determined whether or not an i-th unusable block matches the physical block number Nphy. When they do not match, the flow advances to step S14. At step S14, it is determined whether or not the physical block number Nphy is equal to or smaller than the i-th unusable block.
When the determined result at step S14 represents that the physical block number Nphy is neither equal to nor smaller than the i-th unusable block, the flow advances to step S15. At step S15, i is incremented. At step S16, it is determined whether or not i is equal to or larger than (k−1). At steps S13, S14, S15, and S16, it is determined whether or not the physical block number Nphy is an unusable block number.
When the determined result at step S13 represents that the physical block number Nphy matches the i-th unusable block, the flow advances to step S17. At step S17, an i-th substitute block is used instead of the physical block number Nphy. Thereafter, the process is completed. When the determined result at step S14 represents that the physical block number Nphy is equal to or smaller than the i-th unusable block, the flow advances to step S18. At step S18, the physical block number Nphy is not an unusable block, but a usable block. Thereafter, the process is completed. When the determined result at step S16 represents that i is equal to or larger than (k−1), the flow advances to step S18. At step S18, the physical block number Nphy can be used. Thereafter, the process is completed.
In the process shown in
Next, the mapping reference information 12 of the memory apparatus 1 and 1′ will be described. The mapping reference information 12 contains information necessary for converting logical information into physical information.
The content of the mapping reference information 12 is set when the memory apparatus 1, 1′ is structured. When the logical information unit is the same as the physical information unit and logical address 0 matches physical block number 0 in the memory apparatus 1, the logical-physical conversion criterion 15 and the logical-physical conversion multiplier 16 of the mapping reference information 12 are set to “0” and “1”, respectively. When the logical information unit is twice as large as the physical information unit and logical address 0 corresponds to physical block numbers 4 and 5 in the memory apparatus 1, the logical-physical conversion criterion 15 and the logical-physical conversion multiplier 16 of the mapping reference information 12 are set to “4” and “2”, respectively. When the logical information unit is ¼ times as small as the physical information unit and logical addresses 0, 1, 2, and 3 correspond to physical block number 3 in the memory apparatus 1, the logical-physical conversion criterion 15 and the logical-physical conversion multiplier 16 of the mapping reference information 12 are set to “3” and “'¼”, respectively.
When the logical information unit is the same as the physical information unit thereof, the number of physical blocks per cell of the memory portion is 1024, and logical address 0 corresponds to physical block number 2 in the memory apparatus 1′, the logical physical conversion criterion 15, the logical physical conversion multiplier 16, and the physical block number 17 per cell of the mapping reference information 12 are set to “2”, “1”, and “102”, respectively.
With the forgoing mapping reference information 12, a converting process from logical information into physical information is performed. In the system that uses the memory apparatus 1 shown in
Nphy=Nlog×NMUL+NBASE
where NBASE is a designated value of the logical physical conversion criterion 15 and NMUL is a designated value of the logical-physical conversion multiplier 16.
In the system that uses the memory apparatus 1′ shown in
Nphy=(Nlog×NMUL+NBASE)% NBLKNUM
(% represents an operation that obtains the remainder.)
Ncell=(Nlog×NMUL+NBASE)÷NBLKNUM
where NBASE is a designated value of the logical physical conversion criterion 15, NMUL is a designated value of the logical-physical conversion multiplier 16, and NBLKNUM is a designated value per cell.
The forgoing converting process from logical information into physical information is performed by the data processing portion 20. Alternatively, the converting process may be performed by the host system 40. In this case, as an initializing process, the host system 40 should read and retain the content of the memory management information 10 from the memory apparatus 1, 1′.
At step S23, the data processing portion 20 calculates the physical block number Nphy corresponding to the logical address Nlog and the designated values NBASE and NMUL of the mapping reference information 12. At step S24, the data processing portion 20 determines that the physical block number Nphy is not an unusable block with reference to the unusable block correlation table 11. This process corresponds to the process shown in
At step S27, the physical block number Nphy is read from the memory portion 50. The read data is denoted by DATA (Nphy). DATA (Nphy) is supplied to the data processing portion 20 (at step S28). DATA (Nphy) is supplied from the data processing portion 20 to the communicating portion 30 (at step S29). The communicating portion 30 supplies the read data DATA (Nphy) to the host system 40 (at step S30).
Steps S24, S25, S26, S27, S28, S29, and S30 shown in
At step S43, the data processing portion 20 determines that the physical block number Nphy is not an unusable block with reference to the unusable block correlation table 11. At step S44, it is determined whether or not the physical block number Nphy is an unusable block. When the physical block number Nphy is an unusable block, the flow advances to step S45. At step S45, a substitute block number is used instead of the physical block number Nphy.
At step S46, the physical block number Nphy is read from the memory portion 50. The read data is denoted by DATA (Nphy). DATA (Nphy) is supplied to the data processing portion 20 (at step S47). The data processing portion 20 supplies DATA (Nphy) to the communicating portion 30 (at step S48). The communicating portion 30 supplies the read data DATA (Nphy) to the host system 40 (at step S49).
At step S53, the data processing portion 20 calculates physical information Nphy and Ncell corresponding to NGlobalphy and designated values NBASE, NMUL, and NBLKNUM of the mapping reference information 12. At step S54, the data processing portion 20 determines that the physical information Nphy, Ncell is not an unusable block with reference to the unusable block correlation table 11. At step S55, it is determined whether or not Nphy, Ncell is an unusable block. When Nphy, Ncell is an unusable block, the flow advances to step S56. At step S56, a substitute block number is used instead of Nphy, Ncell.
At step S57, physical information Nphy. Ncell is read from the memory portion 56. The read data is denoted by DATA (Ncell, Nphy). DATA (Ncell, Nphy) is supplied to the data processing portion 20 (at step S58). The data processing portion 20 supplies DATA (Ncell, Nphy) to the communicating portion 30 (at step S59). The communicating portion 30 supplies the read data DATA (Ncell, Nphy) to the host system 40 (at step S60).
Immediately after the writing process is completed, the reading process is performed with the physical block number Nphy (at step S74). The read data is denoted by DATAR (Nphy). At step S75, DATAR (Nphy) is compared with DATAW (Nphy) (write data). When they match, assuming that the writing process has been normally completed, the process is completed (at step S76).
When the determined result at step S75 represents that the read data matches the write data, it is determined that the writing process has not been normally performed. At step S77, the physical block number Nphy is added to the unusable block correlation table. At step S78, the data processing portion 20 decides a substitute block corresponding to the physical block number Nphy. At step S79, the substitute block is designated as a content of the unusable block correlation table. At step S80, the physical block number Nphy is substituted with the designated substituted block number. Thereafter, the flow returns to step S71.
It should be noted that the present invention is not limited to the forgoing embodiment. In other words, without departing from the spirit of the present invention, various modifications and applications of the forgoing embodiment are available. For example, when the contents of the unusable block correlation table have been sorted in the ascending order, it is determined whether or not a physical block number of a block to be processed is larger (smaller) than ½ of the maximum physical block number. Corresponding to the determined result, the determination order of whether or not an objective block is an unusable block may be selected. In other words, the ascending order or descending order is selected.
According to the present invention, since the correlation table does not contain logical information and physical information for all blocks, the storage capacity of the irreversibly write memory open to the user can be increased. In addition, according to the present invention, since a conversion between logical information and physical information can be performed by a calculation, even if mapping information is lost, data can be accessed to some extent.
Filing Document | Filing Date | Country | Kind | 371c Date |
---|---|---|---|---|
PCTJP01/08971 | 10/12/2001 | WO | 00 | 10/21/2002 |
Publishing Document | Publishing Date | Country | Kind |
---|---|---|---|
WO0231661 | 4/18/2002 | WO | A |
Number | Name | Date | Kind |
---|---|---|---|
5226168 | Kobayashi et al. | Jul 1993 | A |
5963738 | Yamaki et al. | Oct 1999 | A |
5968187 | Robinson | Oct 1999 | A |
6282645 | Yamaki | Aug 2001 | B1 |
6341085 | Yamagami et al. | Jan 2002 | B1 |
6446177 | Tanaka et al. | Sep 2002 | B1 |
6675276 | Schulze et al. | Jan 2004 | B2 |
20030210587 | Yamagami et al. | Nov 2003 | A1 |
Number | Date | Country |
---|---|---|
3-97050 | Apr 1991 | JP |
3-156524 | Jul 1991 | JP |
4-133149 | May 1992 | JP |
2000-11677 | Jan 2000 | JP |
2000-285001 | Oct 2000 | JP |
WO-9732253 | Sep 1997 | WO |
WO-0050997 | Aug 2000 | WO |
Number | Date | Country | |
---|---|---|---|
20030131194 A1 | Jul 2003 | US |