JP2009157807A - Memory controller, flash memory system provided with memory controller, and method for controlling flash memory - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide technology for managing association between a logical page (or a logical sector region) and a physical page (or a physical sector region) in order to efficiently obtain the association between the logical page (or the logical sector region) and the physical page (or the physical sector region). <P>SOLUTION: A memory controller is configured to prepare page management information (or sector management information) showing association between a physical page (or a physical sector region) in a physical block with a series of data written therein and a logical page (or a logical sector region) in a logical block corresponding to the physical block. The prepared page management information (or the prepared sector management information) is written in a physical page (or a physical sector region) following the physical page (or the physical sector region) with final data of the series of data written therein. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a memory controller, a flash memory system including the memory controller, and a flash memory control method.

  Conventionally, data corresponding to each logical page given from the host system is not stored in the host system without fixing the correspondence between the logical page included in the logical block and the physical page included in the physical block corresponding to the logical block. There is known a method of writing to physical pages in a physical block in the order given by (see, for example, Patent Document 1). In such a writing method, since data given from the host system is written in order from the head to a page in which data in the physical block is not written, data can be easily rewritten. On the other hand, when data is read, since the correspondence between the logical page and the physical page is not fixed, it is necessary to grasp the correspondence between the logical page and the physical page.

JP 2005-196736

  If information specifying the logical page (or logical sector area) such as the number of the logical page (or logical sector area) corresponding to the redundant area of each physical page is written, the logical page (or logical page) is written based on this information. The correspondence relationship between the sector area) and the physical page (or physical sector area) can be grasped.

  However, the information specifying the logical page (or logical sector area) is sequentially read from each physical page where data is written, and the correspondence between the logical page (or logical sector area) and the physical page (or physical sector area) is determined. To grasp, processing efficiency is not good.

  Therefore, the present invention provides a logical page (or logical sector area) and a physical page (or physical sector) that can efficiently grasp the correspondence between the logical page (or logical sector area) and the physical page (or physical sector area). The purpose is to provide the management technology of the correspondence relationship of (region).

A memory controller according to the first aspect of the present invention comprises:
A memory controller that controls access to a flash memory that is erased in units of physical blocks including a plurality of physical sector areas, based on an access instruction given from a host system,
A block management means for managing a correspondence relationship between a logical block composed of a plurality of logical sector areas and the physical block;
Empty sector area search means for searching for the beginning of the physical sector area in which data in the physical block corresponding to the logical block to which the logical access area specified as the area to be accessed by the access instruction belongs is not written;
A series of data instructed to be written to the logical access area by the access instruction is transferred from the head physical sector area to which the data detected by the free sector area search means is not written, to the physical address at the end. Data writing means for sequentially writing toward the sector area;
Sector management information indicating a correspondence relationship between the physical sector area in the physical block in which the series of data is written by the data writing unit and the logical sector area in the logical block corresponding to the physical block, Sector management information writing means for writing to the physical sector area next to the physical sector area in which the end data of the series of data is written;
Is provided.

  In a preferred embodiment, the sector management information writing means applies the physical management to all the physical sector areas to which data in the physical block in which the series of data has been written by the data writing means. When the logical sector areas in the logical block corresponding to the block correspond in order from the top, the sector management is performed in the physical sector area next to the physical sector area in which the end data of the series of data is written. Do not write information.

  In a preferred embodiment, the sector management information writing means includes sector management information creating means. The sector management information creating means, when instructed to write the series of data to the logical access area by the access instruction, in the physical block corresponding to the logical block to which the logical access area belongs When the sector management information is stored in the physical sector area at the end where data is written, based on the sector management information, the next physical sector area to which the end data of the series of data is written The sector management information to be written in the physical sector area is created.

  In a preferred embodiment, the sector management information creating means corresponds to the logical block to which the logical access area belongs when the access instruction is instructed to write the series of data to the logical access area. If the sector management information is not stored in the physical sector area at the end where data in the physical block is written, the physical sector area in which data in the physical block is written is stored. The logical sector area in the logical block corresponding to the physical block is considered to correspond in order from the beginning, and the physical sector area next to the physical sector area in which the end data of the series of data is written The sector management information to be written in is created.

  In a preferred embodiment, the data stored in the physical sector area in the physical block corresponding to the logical block to which the logical access area specified by the access instruction belongs is written into the data in the physical block. And a data reading means for reading based on the sector management information stored in the last physical sector area.

  In a preferred embodiment, the data reading means writes the data in the physical block when the sector management information is not stored in the physical block corresponding to the logical block to which the logical access area belongs. It is assumed that the logical sector area in the logical block corresponding to the physical block corresponds to the physical sector area corresponding to the physical block in order from the top, and data is read out.

A memory controller according to the second aspect of the present invention comprises:
A memory controller that controls access to a flash memory that is erased in units of physical blocks including a plurality of physical pages, based on an access instruction given from a host system,
Block management means for managing a correspondence relationship between a logical block composed of a plurality of logical pages and the physical block;
Empty page search means for searching for the top of the physical page in which data in the physical block corresponding to the logical block to which the logical access page designated as the logical page to be accessed belongs by the access instruction belongs,
A series of data instructed to be written to the logical access page by the access instruction is transferred from the first physical page to which the data detected by the empty page search unit is not written to the last physical page. Data writing means for sequentially writing toward the
Page management information indicating a correspondence relationship between the physical page in the physical block in which the series of data is written by the data writing unit and the logical page in the logical block corresponding to the physical block; Page management information writing means for writing to the physical page next to the physical page in which the end data of the data is written;
Is provided.

  In a preferred embodiment, the page management information writing unit is configured to apply the physical block to all the physical pages in which data in the physical block in which the series of data is written by the data writing unit is written. The page management information is not written to the physical page next to the physical page in which the end data of the series of data is written when the logical pages in the logical block corresponding to .

  In a preferred embodiment, the page management information writing means includes page management information creating means. The page management information creation means, when instructed to write the series of data to the logical access page by the access instruction, in the physical block corresponding to the logical block to which the logical access page belongs When the page management information is stored in the last physical page in which data is written, the physical next to the physical page in which the last data of the series of data is written based on the page management information The page management information written on the page is created.

  In a preferred embodiment, the page management information creation means corresponds to the logical block to which the logical access page belongs when the access instruction is instructed to write the series of data to the logical access page. When the page management information is not stored in the last physical page in which the data in the physical block is written, the physical page in which the data in the physical block is written The page management that considers that the logical pages in the logical block corresponding to the physical block correspond in order from the top, and writes to the physical page next to the physical page to which the end data of the series of data is written Create information.

  In a preferred embodiment, data stored in the physical page in the physical block corresponding to the logical block to which the logical access page specified by the access instruction belongs is written into the data in the physical block. And a data reading means for reading based on the page management information stored in the last physical page.

  In a preferred embodiment, the data reading means writes the data in the physical block when the page management information is not stored in the physical block corresponding to the logical block to which the logical access page belongs. For the physical page, the logical pages in the logical block corresponding to the physical block are considered to correspond in order from the top, and data is read out.

  A flash memory system according to a third aspect of the present invention includes a memory controller according to any one of the first and second aspects, and a flash memory accessed by the memory controller.

A method for controlling a flash memory according to the fourth aspect of the present invention includes:
A flash memory control method in which erasure is performed in units of physical blocks including a plurality of physical sector areas based on an access instruction given from a host system,
A block management step for managing a correspondence relationship between a logical block composed of a plurality of logical sector areas and the physical block;
A free sector area search step for searching for the beginning of the physical sector area in which data in the physical block corresponding to the logical block to which the logical access area designated as the access target area by the access instruction belongs is not written;
A series of data instructed to be written to the logical access area by the access instruction is transferred from the first physical sector area to which the data detected in the free sector area search step is not written to the last physical sector. A data writing step of sequentially writing toward the sector area;
Sector management information indicating a correspondence relationship between the physical sector area in the physical block in which the series of data is written in the data writing step and the logical sector area in the logical block corresponding to the physical block, Sector management information writing step for writing to the physical sector area next to the physical sector area in which the end data of the series of data is written;
Is provided.

A control method of a flash memory according to the fifth aspect of the present invention is:
A flash memory control method in which erasure is performed in units of physical blocks including a plurality of physical pages based on an access instruction given from a host system,
A block management step for managing a correspondence relationship between a logical block composed of a plurality of logical pages and the physical block;
A free page search step of searching for the top of the physical page in which data in the physical block corresponding to the logical block to which the logical access page designated as the logical page to be accessed by the access instruction belongs is not written;
A series of data instructed to be written to the logical access page by the access instruction is transferred from the first physical page to which the data detected in the empty page search step is not written to the last physical page. A data writing step of sequentially writing toward the
Page management information indicating a correspondence relationship between the physical page in the physical block in which the series of data is written in the data writing step and the logical page in the logical block corresponding to the physical block; A page management information writing step for writing to the physical page next to the physical page in which the end data of the data is written;
Is provided.

  Correspondence between logical page (or logical sector area) and physical page (or physical sector area) that can efficiently grasp the correspondence between logical page (or logical sector area) and physical page (or physical sector area) Management technology can be provided.

  Hereinafter, some embodiments of the present invention will be described in detail with reference to the drawings.

  <First Embodiment>.

  FIG. 1 is a block diagram schematically showing a flash memory system 1 according to the first embodiment of the present invention.

  As shown in FIG. 1, the flash memory system 1 includes a flash memory 2 and a memory controller 3 that controls the flash memory 2.

  The flash memory system 1 is connected to the host system 4 via the external bus 13. The host system 4 is composed of a CPU (Central Processing Unit) for controlling the entire operation of the host system 4, a companion chip for transferring information to and from the flash memory system 1, and the like. The host system 4 may be various information processing apparatuses such as a personal computer and a digital still camera that process various types of information such as characters, sounds, and image information.

  As shown in FIG. 1, the memory controller 3 includes a microprocessor 6, a host interface block 7, a work area 8, a buffer 9, a flash memory interface block 10, an ECC (Error Collection Code) block 11, and a ROM. (Read Only Memory) 12. The memory controller 3 is connected to the flash memory 2 via the internal bus 14. The memory controller 3 constituted by these functional blocks is integrated on one semiconductor chip. Hereinafter, each functional block will be described.

  The host interface block 7 exchanges data, address information, status information, external commands and the like with the host system 4. The external command is a command for the host system 4 to instruct the flash memory system 1 to execute processing. Data or the like supplied from the host system 4 to the flash memory system 1 is taken into the flash memory system 1 (for example, the buffer 9) using the host interface block 7 as an entrance. Data supplied from the flash memory system 1 to the host system 4 is supplied to the host system 4 through the host interface block 7 as an exit.

  The host interface block 7 includes a command register R1, a sector number register R2, and an LBA register R3. Information given from the host system 4 is written in the command register R1, the sector number register R2, and the LBA register R3. External commands such as a write command and a read command are written in the command register R1. The number of sectors in the access target area is written in the sector number register R2. LBA (Logical Block Address) (described later) of the access target area is written in the LBA register R3.

  The work area 8 is a work area for temporarily storing data necessary for controlling the flash memory 2, and is composed of a plurality of SRAM (Static Random Access Memory) cells. The work area 8 stores, for example, an address conversion table (described later) indicating the correspondence between logical blocks and physical blocks.

  The buffer 9 holds the data read from the flash memory 2 until the host system 4 can receive the data. The buffer 9 holds data to be written to the flash memory 2 until the flash memory 2 is in a writable state.

  The flash memory interface block 10 exchanges data, address information, status information, internal commands, and the like with the flash memory 2 via the internal bus 14. Here, the internal command is a command for the memory controller 3 to instruct the flash memory 2 to execute processing, and the flash memory 2 operates in accordance with the internal command given from the memory controller 3.

  The ECC block 11 generates an error correction code (ECC) added to data to be written to the flash memory 2 and is included in the read data based on the error correction code added to the read data. Detect and correct errors.

  The ROM 12 is a non-volatile storage element that stores a program that defines a processing procedure performed by the microprocessor 6. For example, a program that defines a processing procedure such as creation of an address conversion table is stored.

  The microprocessor 6 controls the overall operation of the memory controller 3 in accordance with a program stored in the ROM 12. For example, the microprocessor 6 causes the flash memory interface block 10 to execute processes based on a command set that defines various processes read from the ROM 12.

  The flash memory 2 is a NAND flash memory. The NAND flash memory includes a register and a memory cell array in which a plurality of memory cells are two-dimensionally arranged. The memory cell array includes a plurality of memory cell groups and word lines. Here, the memory cell group is a group in which a plurality of memory cells are connected in series. Each word line is for selecting a specific memory cell in the memory cell group. Data is written from the register to the selected memory cell or data is read from the selected memory cell to the register between the selected memory cell and the register via the word line.

  In the NAND flash memory, a data read operation and a data write operation are performed in units of pages (physical pages), and a data erase operation is performed in units of blocks (physical blocks). A physical block is composed of a plurality of pages (physical pages). For example, one physical page includes a user area of a predetermined size (for example, 2048 bytes) and a redundant area of a predetermined size (for example, 64 bytes), and one physical block has a predetermined number (for example, 64). It consists of physical pages. The user area is an area for storing data given from the host system 4, and is configured by a predetermined number (for example, four) of physical sector areas (storage areas in units of 512 bytes). The redundant area is an area for storing additional data such as an error correction code (ECC), logical address information, and a block status (flag).

  FIG. 2 shows a storage area included in one physical page of the NAND flash memory used in this embodiment.

  The user area 25 is an area for storing data given from the host system 4. The redundant area 26 is an area for storing additional data such as an error correction code (ECC), logical address information, and a block status (flag).

  In the present embodiment, as shown in FIG. 2, the user area 25 is used by being divided into one sector (for example, 512 bytes) physical sector area 60 (60a-60d). The redundant area 26 is divided into a common redundant area 50 having a predetermined size (for example, 8 bytes) and a divided redundant area 70 (70a to 70d) having a predetermined size (for example, 14 bytes). Information managed for each physical block such as logical address information and block status (flag) is written in the common redundant area 50 of the first physical page of each physical block.

  The four physical sector areas 60a-60d and the four divided redundant areas 70a-70d have a one-to-one correspondence set in advance. In the present embodiment, the physical sector area 60a is the divided redundant area 70a, the physical sector area 60b is the divided redundant area 70b, the physical sector area 60c is the divided redundant area 70c, and the physical sector area 60d is the divided redundant area 70d. It corresponds. In the divided redundant areas 70a to 70d, information managed for each physical sector area 60 (60a to 60d) such as an error correction code added to data stored in the corresponding physical sector areas 60a to 60d is written. It is.

  As described above, in a NAND flash memory in which one physical page is configured by a user area of m sectors and one physical block is configured by n physical pages, one physical block is m × It can also be handled as a NAND flash memory composed of n physical sector areas (areas per sector). In other words, the NAND flash memory used in the present embodiment can be handled as a NAND flash memory composed of 256 physical sector areas (areas of one sector unit). In the following description, a serial number assigned to a physical sector area in a physical block is referred to as a physical sector number (PSN). For example, when one physical block is composed of 256 physical sector areas, # 0 to # 255 are assigned as PSNs to 256 physical sector areas in each physical block.

  The logical address information is information for determining the correspondence between physical blocks and logical blocks. Therefore, for a physical block having no corresponding logical block such as a physical block from which stored data has been erased, logical address information is not stored in the redundant area 26 (in the common redundant area 50 of the first physical page). .

  The block status (flag) is a flag indicating pass / fail of the physical block. For the initial defective physical block, a block status (flag) indicating a defective block (physical block in which data cannot be normally written) is written by the manufacturer. Some manufacturers also write a block status (flag) indicating the initial defective physical block in the user area.

  The address space on the host system 4 side is managed by an LBA (Logical Block Address) which is a serial number assigned to an area (hereinafter referred to as a logical sector area) divided in units of sectors (512 bytes). In address management performed in the memory controller, a logical block is formed by a plurality of logical sector areas, and one or a plurality of physical blocks are allocated to the logical block.

  In the present embodiment, as shown in FIG. 3, a group of 256 logical sector areas with continuous LBAs is defined as a logical block, and a serial number is assigned to this logical block. Hereinafter, a serial number assigned to a logical block is referred to as a logical block number (LBN). For example, the 256 logical sector areas of LBA # 0- # 255 belong to the logical block of LBN # 0, and the 256 logical sector areas of LBA # 256- # 511 belong to the logical block of LBN # 1. . As described above, the 2048,000 logical sector areas of LBA # 0 to # 20479999 belong to one of 8000 logical blocks of LBN # 0 to # 7999.

  Further, a logical zone is formed by collecting a plurality of logical blocks, and serial numbers are assigned to the logical zones. Hereinafter, the serial number assigned to the logical zone is referred to as a logical zone number (LZN). In the example of FIG. 3, logical zones are formed by sequentially allocating logical blocks having consecutive LBNs to different logical zones. For example, the logical block of LBN # 0 is in the logical zone of LZN # 0, the logical block of LBN # 1 is in the logical zone of LZN # 1, and the logical block of LBN # 2 is in the logical zone of LZN # 2. Sort to logical zone # 7. Similarly, the logical block of LBN # 8 is assigned to the logical zone of LZN # 0, the logical block of LBN # 9 is assigned to the logical zone of LZN # 1, and the logical block of LBN # 10 is assigned to the logical zone of LZN # 2. Go. In this way, 8 logical zones composed of 1000 logical blocks are formed.

  In the example of FIG. 3, a logical zone is formed, but a physical zone is not formed. Regardless of which logical zone, the entire range of physical blocks is assigned to each logical zone. Therefore, the logical zone is simply a unit for creating an address conversion table, and any logical block may be assigned to any physical block.

  This address conversion table is a table describing the correspondence between logical blocks and physical blocks, and is created in units of logical blocks assigned to each logical zone. This address conversion table is stored in the flash memory 2. In addition, in order to manage the area in the logical block and the area in the physical block that have a correspondence relationship, the correspondence relation between the logical sector area and the physical sector area 60 is grasped by a method described later (note that the second sector described later In the embodiment, the correspondence between a logical page (described later) and a physical page is grasped).

  Note that the physical blocks in the flash memory include innate defective blocks that are defective from the time of shipment. Furthermore, even if a physical block is a non-defective product at the time of shipment, there is a physical block (acquired defective block) that deteriorates after use and becomes a defective block. Therefore, in this embodiment, 8192 physical blocks are assigned to 8000 logical blocks.

  In the first embodiment, the correspondence between 256 logical sector areas included in a logical block and 256 physical sector areas 60 included in a physical block is managed in units of sectors. One physical page includes four physical sector areas 60. The NAND flash memory according to the first embodiment is a NAND flash memory that can execute data writing for each physical page separately for each physical sector area 60. In other words, data writing to the four physical sector areas 60 included in one physical page can be executed four times.

  In the write process of the first embodiment, the host system 4 writes a command code indicating a write command to the command register R1, writes the number of sectors of data to be written to the sector number register R2, and writes to the LBA register R3. The LBA corresponding to the top data for starting writing is written. Based on the information written in the sector number register R2 and the LBA register R3, the logical access area that is the access target area is determined, and the data in the physical block corresponding to the logical block including the logical access area is written. Data given from the host system 4 is written from the head of the physical sector area 60 that is not.

  When the logical access area determined based on the information written in the sector number register R2 and the LBA register R3 extends over a plurality of logical blocks, there are a plurality of physical blocks to which data is written. Therefore, when the logical access area extends over a plurality of logical blocks, the area is divided for each logical block to which the logical access area belongs, and data write processing is performed. For example, when the logical access area extends over two logical blocks (the first logical block and the second logical block), the write processing for the physical block corresponding to the first logical block and the second logical block Write processing is performed on the physical block corresponding to the block. Data instructed to be written to the logical access area belonging to the first logical block is written to the physical sector area 60 in which data in the physical block corresponding to the first logical block is not written. The data instructed to be written to the logical access area belonging to the second logical block is written to the physical sector area 60 where data in the physical block corresponding to the second logical block is not written.

  In the following description, in the data writing process of one sector or a plurality of sectors executed based on information given from the host system 4 (that is, information written in the command register R1, the sector number register R2, and the LBA register R3), The data to be written is called “a series of data”. For example, when the value written in the sector number register R2 is n (n is an integer of 1 or more), data in which LBAs for n sectors are continuous corresponds to a series of data. When the logical access area extends over a plurality of logical blocks, a series of data is divided for each logical block. For example, when the logical access area extends over two logical blocks (the first logical block and the second logical block), the number of sectors in the logical access area belonging to the first logical block is p sectors, If the number of sectors in the logical access area belonging to the logical block 2 is q sectors, even if the value written in the sector number register R2 is n (n = p + q), the series of data is a series of p sectors. The data is divided into a series of data of q sectors.

  The host system 4 indicates the address of the data to be written or the address of the data to be read by LBA. That is, the LBA discriminated based on the information written in the sector number register R2 and the LBA register R3 (when the value written in the sector number register R2 is 1), or the range where the LBA is continuous (sector number register R2 When the value written in (2) is 2 or more), the address indicating the write destination of the data to be written or the address indicating the read source of the data to be read is obtained.

Here, when the number of logical sector areas included in one logical block is 2 ⁱ (for example, 256 when i = 8), the lower i bits of the LBA (for example, lower when i = 8) 8 bits) corresponds to the serial number assigned to the logical sector area in the logical block. Hereinafter, the serial number assigned to the logical sector area in the logical block is referred to as “logical sector number (LSN)”. On the other hand, the serial number assigned to the physical sector area 60 in the physical block is referred to as “physical sector number (PSN)”. Further, the upper bits of the LBA excluding the lower i bits of the LBA (for example, the lower 8 bits when i = 8) correspond to the LBN (logical block number) described above. Therefore, it corresponds to the LBN of the LBA of the first logical sector area and the last logical sector area in the logical access area (the range where the LBA continues) determined based on the information written in the sector number register R2 and the LBA register R3. If the value indicated by the bit of the part to be processed is the same, the logical access area does not extend over a plurality of logical blocks.

  Hereinafter, an outline of writing in the present embodiment will be described.

  The memory controller 3 writes a series of data given together with the write instruction to the flash memory 2 in accordance with a write instruction (write command and write destination address) given from the host system 4. In this write processing, a logical block to which a write-destination logical sector area belongs is specified, and a series of data is written to a physical block corresponding to the logical block (or a physical block newly allocated to the logical block). It is. A series of data is written in the physical sector area 60 in the physical block in order from the top (that is, in order from the smallest PSN). Therefore, when writing a series of data, the end of the physical sector area where the data in the physical block is written is searched. Then, a series of data is sequentially written from the physical sector area 60 next to the last physical sector area 60. In other words, a series of data is sequentially written from the first physical sector area in which data in the physical block is not written.

  In the present embodiment, information indicating the correspondence between the logical sector area and the physical sector area 60 (hereinafter referred to as “sector management information”) in the physical sector area 60 next to the physical sector area 60 in which the end data of a series of data is written. For example, a table indicating the correspondence between the logical sector area and the physical sector area 60 is written. In other words, the sector management information is written in the user area 25 (physical sector area 60) in the same manner as a series of data given together with a write instruction from the host system 4. Accordingly, the correspondence between the logical sector area and the physical sector area 60 is grasped by searching the end of the physical sector area 60 in which data in the physical block is written and reading the sector management information from the physical sector area 60. be able to. In this embodiment, the sector management information is, for example, a table having 256 records corresponding to the logical sector numbers of 256 logical sector areas (see, for example, FIG. 5A described later).

  It should be noted that the latest sector management information regarding the correspondence between the logical sector area and the physical sector area 60 needs to be stored in the last physical sector area 60 in which data in the physical block is written. Therefore, when writing a series of data, the sector management information is read from the last physical sector area 60 in which the data in the physical block to which the series of data is written is written, and the latest sector in which the sector management information is updated is read. The management information is written in the physical sector area 60 next to the physical sector area 60 in which the end data of the series of data is written. In this sector management information update, the contents of the read sector management information are updated for the portion corresponding to the series of data to be written. When sector management information is written in the physical sector area 60, it is possible to determine whether or not the data stored in the physical sector area 60 at the end where the data in the physical block is written is the sector management information. Therefore, in this embodiment, a flag (hereinafter referred to as “management flag”) means that the sector management information is written in the divided redundant area 70 corresponding to the physical sector area 60 to which the sector management information is written. Write. Thus, if the management flag is stored in the divided redundant area 70 corresponding to the last physical sector area 60 in which the data in the physical block is written, the data stored in the last physical sector area 60 is stored. Is sector management information, and if the management flag is not stored, it can be seen that the data stored in the physical sector area 60 at the end is the end data of a series of data.

  Further, when a plurality of series of data is continuously written in the same physical block, the work area is not read out from the last physical sector area 60 in which the data in the physical block is written. The information regarding the correspondence relationship between the logical sector area and the physical sector area 60 held in FIG. 8 may be used as it is.

  Further, when all the data written in the physical block is stored in each physical sector area 60 in the order of the logical sector area (LSN order) from the data corresponding to the head logical sector area, The sector management information may not be written in the physical sector area 60 next to the physical sector area 60 in which the end data of the series of data is written. When the sector management information is not written in the last physical sector area 60 in which the data in the physical block is written as described above, that is, in the last physical sector area 60 in which the data in the physical block is written. If the end data of a series of data is written to the physical block, it is determined that the data is stored in the physical block in the order of the logical sector area (LSN order) from the data corresponding to the head logical sector area. The correspondence relationship between the logical sector area and the physical sector area 60 is grasped.

  When all of the data for a plurality of sector areas given together with the write instruction given from the host system 4 cannot be written to the empty sector area in the write destination physical block, the last physical sector area 60 in the physical block The data given from the host system 4 is written up to the physical sector area 60 one sector area before, and the last physical sector area 60 is a sector indicating the correspondence between the logical sector area and the physical sector area 60 at that time. Write management information. For the remaining data, another physical block is newly allocated, written in the physical sector area 60 in the physical block, and in the physical sector area 60 next to the physical sector area 60 in which the tail data of the remaining data is written. Sector management information indicating the correspondence between the logical sector area and the physical sector area 60 at that time is written. When two physical blocks are allocated to one logical block in this way, the two physical blocks are combined with the physical block allocated later (second physical block). Sector management information indicating the correspondence between the logical sector area and the physical sector area 60, that is, sector management information including information indicating the correspondence between the logical sector area and the physical sector area 60 in the first physical block is written. . In the first physical block, the physical sector area 60 next to the physical sector area 60 in which the end data of the series of data is written is one sector in the last physical sector area 60 of the first physical block. In the case of the previous physical sector area 60, the next series of data is written not from the last physical sector area 60 but from the first physical sector area 60 of the second physical block.

  As described above, when all of the data for a plurality of sector areas given together with the write instruction given from the host system 4 cannot be written in the empty sector area in the write destination physical block (first physical block) The data that could not be written to the physical block (first physical block) is written to the newly allocated physical block (second physical block). In such a case, since the head data written to the newly allocated physical block (second physical block) does not correspond to the head logical sector area, the newly allocated physical block (second physical block) In the writing process for (block), sector management information is always written. Accordingly, when data for a plurality of sector areas given together with a write instruction given from the host system 4 is written across two physical blocks, the sector is stored in the last physical sector area 60 of the first physical block. It is not necessary to write management information. When reading the data stored in each physical sector area 60 from the physical block, the sector management information is read from the last physical sector area 60 where the data in the physical block is written, and the logical sector is based on this sector management information. The correspondence between the area and the physical sector area 60 is grasped.

  A specific example of writing in the present embodiment will be described below with reference to FIGS. As described above, a series of data is written in order from the smallest PSN. Hereinafter, a series of data written in the nth (n is a natural number) is referred to as an “nth series of data”.

  First, from the first write instruction from the host system 4, 16 logical sector areas of LBA # 0 to # 15 (logical sectors of LSN # 0 to # 15 in the logical block of LBN # 0) are used as logical access areas. Area). Since there is no physical block corresponding to the logical block to which this logical access area belongs, a new physical block is allocated to this logical block. Since no data has been written yet in this physical block, the first physical sector area 60 (PSN # 0 physical sector area) in the physical block is used as the first physical sector area 60 in which no data in the physical block is written. 60) is specified. A series of data given from the host system 4 is written from the top physical sector area 60 (PSN # 0 physical sector area 60). As a result, the first series of data corresponding to the 16 logical sector areas of LSN # 0- # 15 is written to the 16 physical sector areas 60 of PSN # 0- # 15 (FIG. 4A). reference). When this writing process is started, the LSN value of the logical sector area corresponding to the head data of a series of data matches the PSN value of the physical sector area to which the head data is written. Thus, it can be determined that a series of data is written in the order of the logical sector areas (LSN order) from the data corresponding to the top logical sector area.

  At this stage, all the data written in the physical block is stored in each physical sector area 60 in the order of LSN from the data corresponding to the head logical sector area (LSN # 0 logical sector area). Yes. That is, in all the physical sector areas 60 in which data in the physical block is written, the PSN of the physical sector area 60 and the LSN of the logical sector area corresponding to the data stored in the physical sector area 60 are the same number. It is. Accordingly, the sector in the physical sector area 60 (PSN # 16 physical sector area 60) next to the physical sector area 60 (PSN # 15 physical sector area 60) in which the end data of the first series of data is stored is stored. Do not write management information.

  Next, from the second write instruction from the host system 4, 16 logical sector areas of LBA # 16- # 31 (logics of LSN # 16- # 31 in the logical block of LBN # 0) are used as logical access areas. (Sector area) is specified. Further, the physical sector area 60 of PSN # 15 is specified as the last physical sector area 60 in which data in the physical block is written. A series of data given from the host system 4 is written from the physical sector area 60 (physical sector area 60 of PSN # 16) next to the identified last physical sector area 60 (physical sector area 60 of PSN # 15). . As a result, the second series of data corresponding to the 16 logical sector areas of LSN # 16- # 31 is written to the 16 physical sector areas 60 of PSN # 16- # 31 (FIG. 4A). reference). Since the sector management information is not written in the last physical sector area 60 (the physical sector area 60 of PSN # 15) where the data in the physical block is written when this writing process is started, at this time, It can be determined that a series of data is written in the order of the logical sector areas (LSN order) from the data corresponding to the first logical sector area in the physical sector area 60 in the physical block. Further, since the LSN value of the logical access area corresponding to the head data of the series of data written by this writing process matches the PSN value of the physical sector area to which the head data is written, this series of data It can be determined that this state is maintained even after writing.

  Even at this stage, the PSN of the physical sector area 60 and the LSN of the logical sector area corresponding to the data stored in the physical sector area 60 are the same in all the physical sector areas 60 in which data in the physical block is written. It is the same number. Therefore, the physical sector area 60 (PSN # 32 physical sector area 60) next to the physical sector area 60 (PSN # 31 physical sector area 60) in which the end data of the second series of data is stored is also stored. Sector management information is not written.

  Next, from the third write instruction from the host system 4, 32 logical sector areas of LBA # 48- # 79 (logics of LSN # 48- # 79 in the logical block of LBN # 0) are used as logical access areas. (Sector area) is specified. Further, the physical sector area 60 of PSN # 31 is specified as the last physical sector area 60 in which data in the physical block is written. A series of data given from the host system 4 is written from the physical sector area 60 (physical sector area 60 of PSN # 32) next to the identified end physical sector area 60 (physical sector area 60 of PSN # 31). . As a result, the third series of data corresponding to the 32 logical sector areas of LSN # 48- # 79 is written into the 32 physical sector areas 60 of PSN # 32- # 63 (FIG. 4A). reference). Since the sector management information is not written in the last physical sector area 60 (the physical sector area 60 of PSN # 31) where the data in the physical block is written when this writing process is started, at this time, It can be determined that a series of data is written in the order of the logical sector areas (LSN order) from the data corresponding to the first logical sector area in the physical sector area 60 in the physical block. However, since the LSN value of the logical access area corresponding to the head data of the series of data written by this writing process does not match the PSN value of the physical sector area to which the head data is written, this series of data After writing, it can be determined that this state is not maintained.

  At this stage, a part of all physical sector areas 60 in which data in the physical block is written (that is, 32 physicals PSN # 32- # 63 in which the third series of data is stored). In the sector area 60), the PSN of the physical sector area 60 and the LSN of the logical sector area corresponding to the data stored in the physical sector area 60 have different numbers. In this case, the memory controller 3 uses the sector management information indicating the correspondence between all the physical sector areas 60 (physical sector areas 60 of PSN # 0 to # 63) in which data in the physical block is written and the logical sector areas. Create # 0. Here, since sector management information is not written in the last physical sector area 60 (PSN # 31 physical sector area 60) before the third series of data is written (corresponding to the last physical sector area 60). Since the management flag is not written in the divided redundant area 70), new sector management information is created. Specifically, a table creation area having 256 records respectively corresponding to LSN # 0-255 is secured on the work area 8, and the PSN is written into this table creation area. In the case of sector management information # 0, as shown in FIG. 5A, 32 physical sector areas in which a third series of data is written in 32 records corresponding to LSN # 48-79. PSN # 32- # 63 corresponding to 60 is written. Further, the physical sector area 60 before the physical sector area 60 of PSN # 32 in which the top data of the third series of data is written is in the order of the logical sector area from the data corresponding to the top logical sector area. It is determined that data is stored, and PSN # 0-31 is written in 32 records corresponding to LSN # 0- # 31. Thereby, the creation of the sector management information # 0 is completed. The memory controller 3 uses the created sector management information # 0 as the physical sector area 60 (next to the physical sector area 60 (physical sector area 60 of PSN # 63) in which the end data of the third series of data is written. Write to PSN # 64 physical sector area 60). Further, the management flag is written in the divided redundant area 70 corresponding to the physical sector area 60 (PSN # 64 physical sector area 60) in which the sector management information # 0 is written.

  As will be described later, for the physical block in which the sector management information has been written even once, each time a series of data is written to the physical block, the next to the physical sector area 60 in which the end data of the series of data is written. Sector management information is written in the physical sector area 60.

  Next, from the fourth write instruction from the host system 4, 32 logical sector areas of LBA # 16- # 47 (logics of LSN # 16- # 47 in the logical block of LBN # 0) are used as logical access areas. (Sector area) is specified. Further, the physical sector area 60 of PSN # 64 is specified as the last physical sector area 60 in which data in the physical block is written. A series of data given from the host system 4 is written from the physical sector area 60 (physical sector area 60 of PSN # 65) next to the identified last physical sector area 60 (physical sector area 60 of PSN # 64). . As a result, a fourth series of data corresponding to the 32 logical sector areas of LSN # 16- # 47 is written into the 32 physical sector areas 60 of PSN # 65- # 96 (FIG. 4A). reference). Since the sector management information is written in the last physical sector area 60 (the physical sector area 60 of PSN # 64) in which data in the physical block is written when this writing process is started, at this time, It can be determined that a series of data is not written in the order of the logical sector area (LSN order) from the data corresponding to the first logical sector area in the physical sector area 60 in the physical block.

  Further, since the sector management information # 0 is written in the last physical sector area 60 (PSN # 64 physical sector area 60) before the fourth series of data is written (the last physical sector area 60). Sector management information # 0 is read out, and sector management information # 1 is created based on sector management information # 0. That is, the contents of sector management information # 0 are updated for the portion corresponding to the fourth series of data. Specifically, as shown in FIG. 5B, 32 physical sector areas in which a fourth series of data is written in records corresponding to LSN # 16- # 47 in sector management information # 0. Sector management information # 1 is created by writing PSN # 65- # 96 corresponding to 60. The created sector management information # 1 is stored in the physical sector area 60 (PSN # 97 physical physical area) next to the physical sector area 60 (PSN # 96 physical sector area 60) in which the end data of the fourth series of data is written. Write to sector area 60). Also, the management flag is written in the divided redundant area 70 corresponding to the physical sector area 60 (PSN # 97 physical sector area 60) in which the sector management information # 1 is written.

  Thereafter, similarly, the fifth to eighth series of data and the sector management information # 2 to # 5 are written in the same physical block.

  That is, the fifth series of data corresponding to the 32 logical sector areas of LBA # 0 to # 31 (the logical sector areas of LSN # 0 to # 31 in the logical block of LBN # 0) are stored in the physical block. Data is written from the physical sector area 60 (PSN # 98 physical sector area 60) next to the last physical sector area 60 (PSN # 97 physical sector area 60) in which data is written (FIGS. 4A and 4). (See (B)). Also, sector management information # 2 is created based on sector management information # 1 written in the last physical sector area 60 (PSN # 97 physical sector area 60) before the fifth series of data is written. To do. Specifically, as shown in FIG. 5C, 32 physical sector areas in which a fifth series of data is written in records corresponding to LSN # 0- # 31 in the sector management information # 1. By writing PSN # 98-129 corresponding to 60, sector management information # 2 is created. The created sector management information # 2 is stored in the physical sector area 60 (the physical sector area of the PSN # 130) next to the physical sector area 60 (the physical sector area 60 of the PSN # 129) in which the end data of the fifth series of data is written. Write to sector area 60).

  Next, a sixth series of data corresponding to the 16 logical sector areas of LBA # 16- # 31 (the logical sector area of LSN # 16- # 31 in the logical block of LBN # 0) is stored in the physical block. Is written from the physical sector area 60 (PSN # 131 physical sector area 60) next to the last physical sector area 60 (PSN # 130 physical sector area 60) in which data is written (see FIG. 4B). . Also, sector management information # 3 is created based on sector management information # 2 written in the last physical sector area 60 (PSN # 130 physical sector area 60) before the sixth series of data is written. To do. Specifically, as shown in FIG. 6A, 16 physical sector areas in which a sixth series of data is written in records corresponding to LSN # 16- # 31 in the sector management information # 2. By writing PSN # 131-146 corresponding to 60, sector management information # 3 is created. The created sector management information # 3 is stored in the physical sector area 60 (physical sector area 60 of PSN # 147) next to the physical sector area 60 (physical sector area 60 of PSN # 146) in which the end data of the sixth series of data is written. Write to sector area 60).

  Next, the seventh series of data corresponding to the 16 logical sector areas of LBA # 64- # 79 (the logical sector area of LSN # 64- # 79 in the logical block of LBN # 0) is stored in the physical block. Is written from the physical sector area 60 (PSN # 148 physical sector area 60) next to the last physical sector area 60 (PSN # 147 physical sector area 60) in which data is written (see FIG. 4B). . Also, sector management information # 4 is created based on sector management information # 3 written in the last physical sector area 60 (PSN # 147 physical sector area 60) before the seventh series of data is written. To do. Specifically, as shown in FIG. 6B, 16 physical sector areas in which a seventh series of data is written in records corresponding to LSN # 64- # 79 in sector management information # 3. By writing PSN # 148-163 corresponding to 60, sector management information # 4 is created. The created sector management information # 4 is stored in the physical sector area 60 (the physical sector area of PSN # 164) next to the physical sector area 60 (the physical sector area 60 of PSN # 163) in which the end data of the seventh series of data is written. Write to sector area 60).

  Next, the eighth series of data corresponding to the 16 logical sector areas of LBA # 80- # 95 (the logical sector area of LSN # 80- # 95 in the logical block of LBN # 0) is stored in the physical block. Is written from the physical sector area 60 (PSN # 165 physical sector area 60) next to the last physical sector area 60 (PSN # 164 physical sector area 60) in which data is written (see FIG. 4B) . Also, sector management information # 5 is created based on sector management information # 4 written in the last physical sector area 60 (PSN # 164 physical sector area 60) before the eighth series of data is written. To do. Specifically, as shown in FIG. 6C, 16 physical sector areas in which an eighth series of data is written in records corresponding to LSN # 80- # 95 in the sector management information # 4. The sector management information # 5 is created by writing PSN # 165- # 180 corresponding to 60. The created sector management information # 5 is stored in the physical sector area 60 (physical sector area of PSN # 181) next to the physical sector area 60 (physical sector area 60 of PSN # 180) in which the end data of the eighth series of data is written. Write to sector area 60).

  After that, when reading data stored in each physical sector area 60 from the physical block, the memory controller 3 reads the physical sector area 60 (PSN # 181 physical data) at the end where the data in the physical block is written. The sector management information # 5 is read from the sector area 60), and the correspondence between the logical sector area and the physical sector area 60 is grasped based on the sector management information # 5. Here, since the sector management information # 5 written in the physical sector area 60 of PSN # 181 indicates the latest correspondence between the logical sector area and the physical sector area 60, refer to the sector management information # 5. It is possible to grasp the latest correspondence relationship between the logical sector area and the physical sector area 60 simply by doing so. That is, according to the present embodiment, the correspondence relationship between the logical sector area and the physical sector area 60 can be grasped efficiently.

  If the first series of data is written and before the third series of data is written (that is, when no sector management information is written), the data is read from the physical block. Sometimes, the memory controller 3 determines that data is stored in the order of the logical sector area from the data corresponding to the leading logical sector area, and can grasp the correspondence between the logical sector area and the physical sector area 60. it can.

  The above is the description of the first embodiment.

  The sector management information is preferably a table showing the correspondence between the logical sector area and the physical sector area 60 as described above, but as a modification, each series of data written in the physical block Start logical sector number (hereinafter referred to as “SLSN”) which is the logical sector number of the logical sector area corresponding to the head data of the data and the number of sector areas in which the series of data is written (from the sector area where the head data is written to the end data) May be information indicating a sector count value that is the number of sector areas up to the sector area to be written (hereinafter referred to as “SCNT”). Further, information indicating the physical sector number (PSN) of the physical sector area where the head data of each series of data is written may be added to these pieces of information. When such information is written, a table showing the correspondence between the logical sector area and the physical sector area 60 is created based on this information.

  For example, FIGS. 7A to 7F show sector management information # 0 ′ to # 5 ′, which are modifications of the sector management information # 0 to # 5, respectively. In the sector management information # 0 ′ to # 5 ′, the set of the nth SLSN and SCNT corresponds to the nth series of data. Note that a part of a series of data written in the order of the logical sector area (LSN order) from the data corresponding to the first logical sector area in the physical sector area 60 in the physical block is a plurality of series of data. The information corresponding to the information may be integrated into one. For example, the portions corresponding to the first-second series of data may be combined into one, and SLSN may be # 0 and SCNT may be 32.

  In this modification, a table indicating the latest correspondence relationship between the logical sector area and the physical sector area 60 is created based on the latest sector management information. Specifically, a record corresponding to 256 logical sector numbers of LSN # 0 to # 255 is given with priority given to the correspondence relationship between the logical sector area and the physical sector area 60 corresponding to a series of data written later. The physical sector number (PSN) is written. The correspondence relationship between the logical sector area and the physical sector area 60 is grasped based on the combination of SLPN and SCNT.

  For example, a target table as shown in FIG. 6C is created based on the sector management information # 5 ′. In creating this table, a physical sector number (PSN) is written in each record based on the correspondence between the logical sector area and the physical sector area 60 corresponding to each series of data. The writing of the physical sector number (PSN) is performed in order from the one corresponding to the previously written series of data. Even if the physical sector number (PSN) is already written in the write destination record, the physical sector number (PSN) is written later. The physical sector number (PSN) is overwritten. Accordingly, a table is created in which the correspondence between the logical sector area and the physical sector area 60 corresponding to a series of data written later is prioritized.

  <Second Embodiment>.

  Hereinafter, a second embodiment of the present invention will be described. In that case, the difference from the first embodiment will be mainly described, and the description of the common points with the first embodiment will be omitted or simplified.

  In the second embodiment, logical sector areas in a logical block, which are grouped in units of sectors equal to the capacity of the user area 25 included in one physical page 60 in order from the top, are treated as logical pages. The correspondence relationship between the logical page included in the logical block and the physical page included in the physical block is managed in units (number of sectors equal to the capacity of the user area 25 included in one physical page). In the following description, a serial number assigned to a physical page in each physical block is referred to as a physical page number (PPN). A serial number assigned to a logical page in each logical block is called a logical page number (LPN).

  In the present embodiment, one physical page is configured by the user area 25 of 4 sectors (2048 bytes) (4 physical sector areas 60 are included in one physical page), and 64 physical blocks are included. NAND type flash memory composed of physical pages is used. As shown in FIG. 2, with respect to the four physical sector areas 60 included in each physical page, the first physical sector area 60a, the second physical sector area 60a, and second They are referred to as a physical sector area 60b, a third physical sector area 60c, and a fourth physical sector area 60d. Here, the first physical sector area 60a included in the physical page of PPN # 0 corresponds to the physical sector area of PSN # 0, and the second physical sector area 60b included in the physical page of PPN # 0 is PSN # 1. Corresponding to the physical sector area, the third physical sector area 60c included in the physical page of PPN # 0 corresponds to the physical sector area of PSN # 2, and the fourth physical sector area 60d included in the physical page of PPN # 0 is included. This corresponds to the physical sector area of PSN # 3. The first physical sector area 60a, the second physical sector area 60b, the third physical sector area 60c, and the fourth physical sector area 60d included in the physical page of PPN # 1 include the physical sector areas of PSN # 4- # 7. The first physical sector area 60a, the second physical sector area 60b, the third physical sector area 60c, and the fourth physical sector area 60d included in the physical page of the PPN # 63 have the same corresponding relationship. The physical sector areas of PSN # 252- # 255 correspond to each other.

  Each logical page includes four logical sector areas. The LPN # 0 logical page includes LSN # 0- # 3 logical sector areas, the LPN # 1 logical page includes LSN # 4- # 7 logical sector areas, and so on. The allocated logical page of LPN # 63 includes the logical sector area of LSN # 252- # 255. The four logical sector areas included in each logical page are divided into four physical sector areas (first physical sector area 60a, second physical sector area 60b, third physical sector area 60c, and fourth physical area included in each physical page. The physical sector area 60d) is assigned in order from the smallest LSN.

  In the second embodiment, the correspondence relationship between the logical page and the physical page changes, but the relative relationship between the four physical sector areas 60 in the physical page and the four logical sector areas in the logical page changes. do not do. Therefore, in the second embodiment, by managing the correspondence between logical pages and physical pages, 256 logical sector areas included in the logical block and 256 physical sector areas 60 included in the physical block are Correspondence can be managed. That is, as in the present embodiment, if four physical sector areas 60 are included in one physical page, the physical sector area so that the lower 2 bits of the PSN and the lower 2 bits of the LSN always match. Correspondence between 60 and the logical sector area is defined. That is, the data corresponding to the LSN whose lower 2 bits are 00 is stored in the first physical sector 60a, the data corresponding to the LSN whose lower 2 bits are 01 is stored in the second physical sector 60b, and the lower 2 bits are 10 The data corresponding to the LSN is stored in the third physical sector, and the data corresponding to the LSN having the lower 2 bits of 11 is stored in the fourth physical sector. The logical page number (LPN) corresponds to the upper 6 bits of the 8-bit LSN, and the physical page number corresponds to the upper 6 bits of the 8-bit PSN.

  Hereinafter, an outline of writing in this embodiment will be described.

  The memory controller 3 writes a series of data given together with the write instruction to the flash memory 2 in accordance with a write instruction (write command and write destination address) given from the host system 4. In this writing process, the logical block to which the logical page to be written belongs is specified, and a series of data is written to the physical block corresponding to the logical block (or a physical block newly assigned to the logical block). . A series of data is written to the physical pages in the physical block in order from the top (that is, in order from the smallest PPN). Therefore, when writing a series of data, the end of the physical page in which the data in the physical block is written is searched. Then, a series of data is sequentially written from the physical page next to the last physical page. In other words, a series of data is sequentially written from the first physical page in which data in the physical block is not written.

  In the present embodiment, information indicating the correspondence between a logical page and a physical page (hereinafter referred to as “page management information”), such as logical A table indicating the correspondence between pages and physical pages is written. That is, the page management information is written in the user area 25 of the physical page, like the series of data given from the host system 4 together with the write instruction. Therefore, the correspondence between the logical page and the physical page can be grasped by searching the end of the physical page in which data in the physical block is written and reading the page management information from the physical page. In the present embodiment, the page management information is, for example, a table having 64 records respectively corresponding to the logical page numbers of 64 logical pages (for example, see FIG. 9A described later).

  Note that the latest page management information related to the correspondence between the logical page and the physical page needs to be stored in the last physical page in which the data in the physical block is written. Therefore, when writing a series of data, the page management information is read from the last physical page in which the data in the physical block to which the series of data is written is written, and the latest page management information updated with this page management information Are written in the physical page next to the physical page in which the end data of the series of data is written. In the update of the page management information, the content of the read page management information is updated for a portion corresponding to a series of data to be written. Note that when page management information is written to a physical page, in order to be able to determine whether or not the data stored in the physical page at the end where the data in the physical block is written is page management information. In the embodiment, a flag (hereinafter referred to as “management flag”) indicating that page management information has been written is written in the common redundant area 50 of the physical page to which page management information is written. Thus, if the management flag is stored in the common redundant area 50 of the last physical page in which the data in the physical block is written, the data stored in the last physical page is the page management information. If the management flag is not stored, the data stored in the last physical page is the last data of a series of data.

  Further, when a plurality of series of data is continuously written in the same physical block, the page management information is not read from the last physical page in which the data in the physical block is written, and the work area 8 is read. The information regarding the correspondence between the logical page and the physical page that is held may be used as it is.

  If all data written in a physical block is stored in each physical page in the order of logical pages (LPN order) from the data corresponding to the first logical page, a series of data The page management information may not be written in the physical page next to the physical page in which the tail data is written. If page management information is not written to the last physical page in which data in the physical block is written in this way, that is, a series of data in the last physical page in which data in the physical block is written. Is written in the physical block, it is determined that data is stored in the logical page order (LPN order) from the data corresponding to the first logical page. To understand the correspondence of

  If all of the data for a plurality of pages given together with the write instruction given from the host system 4 cannot be written to the empty pages in the write destination physical block, one page before the last physical page in the physical block The data given from the host system 4 is written up to the physical page, and page management information indicating the correspondence between the logical page and the physical page at that time is written into the last physical page. For the remaining data, another physical block is newly allocated, written to the physical page in the physical block, and the physical page next to the physical page in which the last data of the remaining data is written is the current logical page. And page management information indicating the correspondence between physical pages. When two physical blocks are allocated to one logical block in this way, the two physical blocks are combined with the physical block allocated later (second physical block). Page management information indicating the correspondence between logical pages and physical pages, that is, page management information including information indicating the correspondence between logical pages and physical pages in the first physical block is written. In the first physical block, the physical page next to the physical page in which the end data of the series of data is written is the physical page one page before the last physical page of the first physical block. In this case, the next series of data is written not from the last physical page but from the first physical page of the second physical block.

  When reading the data stored in each physical page from the physical block, the page management information is read from the last physical page where the data in the physical block is written, and the logical page and physical page are read based on this page management information. Know the correspondence.

  A specific example of writing in the present embodiment will be described below with reference to FIGS. As described above, a series of data is written in order from the smallest PPN. Hereinafter, a series of data written in the nth (n is a natural number) is referred to as an “nth series of data”. Further, in the following description, one logical page to be accessed (one logical page from the logical page to which the logical sector area corresponding to the first data of the series of data belongs to the logical page to which the logical sector area corresponding to the last data of the series of data belongs) Or a plurality of logical pages) is called a “logical access page”. In this specific example, it is assumed that a physical block of PBA # 7 is allocated to the logical block as shown in FIG.

  First, eight logical pages LPN # 0- # 7 in a logical block of LBN # 0 are specified as logical access pages from the first write instruction from the host system 4. Further, since there is no physical block corresponding to the logical block of LBN # 0, the physical block of PBA # 7 is allocated corresponding to the logical block of LBN # 0. Since data is not yet written in this physical block, the first physical page in the physical block of PBA # 7 (physical page of PPN # 0) is the first physical page in which no data in the physical block is written. Is identified. A series of data given from the host system 4 is written from this first physical page (physical page of PPN # 0). As a result, the first series of data corresponding to the eight logical pages of LPN # 0 to # 7 is written to the eight physical pages of PPN # 0 to # 7 (see FIG. 8A). When starting this writing process, the LPN value of the logical page corresponding to the head data of a series of data matches the PPN value of the physical page to which the head data is written. It can be determined that a series of data is written in the order of logical pages (LPN order) from the data corresponding to the first logical page.

  At this stage, all the data written in the physical block of PBA # 7 is stored in each physical page in the order of the LPN from the data corresponding to the first logical page (LPN # 0 logical page). Yes. Accordingly, the page management information is not written to the physical page (PPN # 8 physical page) next to the physical page (PPN # 7 physical page) in which the tail data of the first series of data is stored.

  Next, from the second write instruction from the host system 4, eight logical pages LPN # 8- # 15 in the logical block of LBN # 0 are specified as logical access pages. Further, the physical page of PPN # 7 is specified as the last physical page in which the data in the physical block of PBA # 7 corresponding to the logical block of LBN # 0 is written. A series of data given from the host system 4 is written from the physical page (physical page of PPN # 8) next to the identified last physical page (physical page of PPN # 7). As a result, the second series of data corresponding to the eight logical pages of LPN # 8- # 15 is written to the eight physical pages of PPN # 8- # 15 (see FIG. 8A). When this writing process is started, the page management information is not written in the last physical page (PPN # 7 physical page) in which data in the physical block is written. It can be determined that a series of data is written in the physical page order (LPN order) from the data corresponding to the first logical page in the physical page. Further, since the LPN value of the logical page corresponding to the top data of the series of data written by this writing process matches the PPN value of the physical page to which the top data is written, this series of data is written. After that, it can be determined that this state is maintained.

  Even at this stage, in all the physical pages in which data in the physical block of PBA # 7 is written, the PPN of the physical page and the LPN of the logical page corresponding to the data stored in the physical page have the same number. is there. Accordingly, the page management information is not written in the physical page (physical page of PPN # 16) next to the physical page (physical page of PPN # 15) in which the tail data of the second series of data is stored.

  Next, from the third write instruction from the host system 4, 16 logical pages LPN # 16- # 31 in the logical block of LBN # 0 are specified as logical access pages. Also, the physical page of PPN # 15 is specified as the last physical page in which the data in the physical block of PBA # 7 corresponding to the logical block of LBN # 0 is written. A series of data given from the host system 4 is written from the physical page (physical page of PPN # 16) next to the identified last physical page (physical page of PPN # 15). As a result, the third series of data corresponding to the 16 logical pages of LPN # 16- # 31 is written to the 16 physical pages of PPN # 16- # 31 (see FIG. 8A). When this writing process is started, the page management information is not written in the last physical page (PPN # 15 physical page) in which data in the physical block is written. It can be determined that a series of data is written in the physical page order (LPN order) from the data corresponding to the first logical page in the physical page. Further, since the LPN value of the logical page corresponding to the top data of the series of data written by this writing process matches the PPN value of the physical page to which the top data is written, this series of data is written. After that, it can be determined that this state is maintained.

  Even at this stage, in all the physical pages in which data in the physical block of PBA # 7 is written, the PPN of the physical page and the LPN of the logical page corresponding to the data stored in the physical page have the same number. is there. Therefore, the page management information is not written to the physical page (physical page of PPN # 32) next to the physical page (physical page of PPN # 31) in which the tail data of the third series of data is stored.

  Next, from the fourth write instruction from the host system 4, 16 logical pages LPN # 48- # 63 in the logical block of LBN # 0 are specified as logical access pages. Further, the physical page of PPN # 31 is specified as the last physical page in which data in the physical block of PBA # 7 corresponding to the logical block of LBN # 0 is written. A series of data given from the host system 4 is written from the physical page (physical page of PPN # 32) next to the identified last physical page (physical page of PPN # 31). As a result, the fourth series of data corresponding to the 16 logical pages of LPN # 48- # 63 is written to the 16 physical pages of PPN # 32- # 47 (see FIG. 8A). When this writing process is started, page management information is not written in the last physical page (physical page of PPN # 31) in which data in the physical block is written. It can be determined that a series of data is written in the physical page order (LPN order) from the data corresponding to the first logical page in the physical page. However, since the LPN value of the logical page corresponding to the top data of the series of data written by this writing process does not match the PPN value of the physical page to which the top data is written, this series of data is written. After that, it can be determined that this state is not maintained.

  At this stage, a part of all physical pages in which data in the physical block of PBA # 7 is written (that is, 16 PPN # 32 to # 47 in which the fourth series of data is stored) The physical page PPN and the logical page LPN corresponding to the data stored in the physical page have different numbers. In this case, the memory controller 3 creates page management information # 0 indicating the correspondence between all physical pages (PPN # 0 to # 47 physical pages) in which data in the physical block is written and logical pages. . Here, since the page management information is not written in the last physical page (PPN # 31 physical page) before the fourth series of data is written (the management flag in the common redundant area 50 of the last physical page). ) Is created, page management information is newly created. Specifically, a table creation area having 64 records respectively corresponding to LPN # 0-63 is secured on the work area 8, and the PPN is written into this table creation area. In the case of page management information # 0, as shown in FIG. 9A, 16 physical pages in which a fourth series of data has been written in 16 records corresponding to LPN # 48-63. Write the corresponding PPN # 32- # 47. In addition, data is stored in the order of logical pages from the data corresponding to the first logical page in the physical page before the physical page of PPN # 32 in which the first data of the fourth series of data is written. Therefore, PPN # 0-31 is written in 32 records corresponding to LPN # 0- # 31. Thereby, the creation of the page management information # 0 is completed. The memory controller 3 uses the created page management information # 0 as the physical page (PPN # 48 physical page) next to the physical page (PPN # 47 physical page) in which the tail data of the fourth series of data is written. ). Further, the management flag is written in the common redundant area 50 of the physical page (PPN # 48 physical page) in which the page management information # 0 is written.

  As will be described later, for a physical block in which page management information has been written even once, each time a series of data is written to the physical block, the physical page next to the physical page in which the end data of the series of data is written To write page management information.

  Next, from the fifth write instruction from the host system 4, 16 logical pages LPN # 32- # 47 in the logical block of LBN # 0 are specified as logical access pages. Further, the physical page of PPN # 48 is specified as the last physical page in which the data in the physical block of PBA # 7 corresponding to the logical block of LBN # 0 is written. A series of data given from the host system 4 is written from the physical page (physical page of PPN # 49) next to the identified last physical page (physical page of PPN # 48).

  However, in this case, a series of data given from the host system 4 cannot be written in all the empty pages in the physical block of PBA # 7. Because the series of data given from the host system 4 is data for 16 pages, the number of free pages in the physical block of PBA # 7 is 15 pages of PPN # 49- # 63, This is because one page is insufficient. Further, since the page management information is written in the last physical page (PSN # 48 physical page) in which data in the physical block is written, at this time, the top in the physical sector area 60 in the physical block. It can be determined that a series of data is not written in the order of the logical sector areas (LPN order) from the data corresponding to the logical sector areas. Therefore, it is possible to determine that two pages are insufficient in consideration of a physical page to which page management information is written.

  Therefore, in this case, the data given from the host system 4 up to the physical page one page before the last physical page (physical page of PPN # 63) in the physical block of PBA # 7 (physical page of PPN # 62). Write. In the last physical page (physical page of PPN # 63) in the physical block of PBA # 7, page management information # 1 indicating the correspondence between the logical page and the physical page at that time is written. For the remaining data, as shown in FIG. 8B, another physical block (physical block of PBA # 16) is newly allocated to the logical block of LBN # 0, and the head in the physical block of PBA # 16 To the physical page (PPN # 2 physical page) next to the physical page (PPN # 1 physical page) in which the last data of the remaining data is written. Page management information # 2 representing the correspondence between the logical page and the physical page at the time is written. As a result, among a series of 16 pages of data provided from the host system 4, a series of 14 pages of data is transferred to the fifth physical page of PPN # 49- # 62 in the physical block of PBA # 7. A series of data is written as a series of data (see FIG. 8A), and the series of data for the remaining two pages is the sixth series of data on the physical pages of PPN # 0- # 1 in the physical block of PBA # 16. (See FIG. 8B). Note that, as described above, when all the data given together with the write instruction from the host system 4 cannot be written to the empty page in the physical block of PBA # 7, all the data of PBA # 16 to which all the data is newly allocated are written. You may make it write in a physical block.

  The page management information # 1 and # 2 described above are created as follows.

  That is, since page management information # 0 is written in the last physical page (PPN # 48 physical page) before the fifth series of data is written (in the common redundant area 50 of the last physical page). Since the management flag is written), the page management information # 0 is read, and the page management information # 1 is created based on the page management information # 0. Specifically, as shown in FIG. 9B, 14 physical pages 60 in which a fifth series of data is written in records corresponding to LPN # 32- # 45 in page management information # 0. The page management information # 1 is created by writing the PPN # 49-62 corresponding to. The created page management information # 1 is stored in the physical page (physical page of PPN # 63) next to the physical page (physical page of PPN # 62) in which the end data of the fifth series of data is written. A management flag is written in the common redundant area 50 of the physical page (physical page of PPN # 63) in which the page management information # 1 is written.

  The page management information # 2 is created using the page management information # 1 held in the work area 8. Specifically, as shown in FIG. 10A, two physical pages 60 in which a sixth series of data is written in records corresponding to LPN # 46- # 47 in page management information # 1. PPN # 0-1 corresponding to is written. In addition, the old block flag (described as “old block F” in the figure) is written in all records other than the records corresponding to these LPNs # 46- # 47. The old block flag indicates that the PPN written in each record is the PPN of the physical page in the old block (physical block PBA # 7 in this specific example) or the new block (PBA # 16 in this specific example). This is information for determining whether it is a PPN of a physical page in the physical block). That is, the PPN written in the record in which the old block flag is written is determined to be the PPN of the physical page in the old block (physical block of PBA # 7 in this specific example). In other words, by referring to the page management information # 2, the data corresponding to the logical pages of LPN # 46- # 47 is written in the new block (in this specific example, the physical block of PBA # 16). It can be seen that the data corresponding to the logical page is written in the old block. The page management information # 2 created as described above is the physical page next to the physical page (the physical page of PPN # 1 in the new block) in which the end data of the sixth series of data is written. The management flag is set in the common redundant area 50 of the physical page (physical page of PPN # 2 in the new block) written to (physical page of PPN # 2 in the new block) and the page management information # 2 is written. Written.

  In this specific example, the fact that the physical block of PBA # 7 and the physical block of PBA # 16 correspond to the same logical block (logical block of LBN # 0) means that the logical address written in these physical blocks This can be determined by referring to the information. In order to determine the new / old relationship of these physical blocks, it is preferable to write a serial number in the common redundant area 50 of the first physical page in order to determine the new / old relationship. Further, the PBA of the old block may be written in the common redundant area 50 of the first physical page of the new block or the common redundant area 50 of the physical page in which the page management information is written. In this way, the PBA of the old block can be grasped by referring to those common redundant areas 50.

  Thereafter, when a series of data is given from the host system 4, the series of data and the latest page management information are written in the physical block of the new block PBA # 16.

  For example, the seventh series of data corresponding to the 16 logical pages of LBA # 0 to # 15 is the last physical page in which data in the physical block of PBA # 16 is written (physical page of PPN # 2). ) From the next physical page (PPN # 3 physical page). Also, page management information # 3 is created based on page management information # 2 written in the last physical page (PPN # 2 physical page) before the seventh series of data is written. Specifically, as shown in FIG. 10 (B), the page management information # 2 includes 16 physical pages in which a seventh series of data is written in records corresponding to LPN # 0 to # 15. The corresponding PPN # 3-18 is written, and the old block flag written in the record corresponding to the LPN # 0- # 15 is erased. The page management information # 3 created in this way is used as the physical page (PPN # 19 physical page) next to the physical page (PPN # 18 physical page) in which the end data of the seventh series of data is written. ).

  After that, when data is read from the old block or new block assigned to the logical block, the memory controller 3 starts from the last physical page in which the data in the new block is written (physical page of PPN # 19). The page management information # 3 is read, and the correspondence between the logical page and the physical page is grasped based on the page management information # 3. Here, since the page management information # 3 written in the physical page of PPN # 3 in the new block indicates the latest correspondence between the logical page and the physical page, the page management information # 3 is referred to. Only the latest correspondence relationship between the logical page and the physical page can be grasped. Specifically, data corresponding to the logical pages of LPN # 0- # 15 and # 46- # 47 are written in the new block, and data corresponding to other logical pages are written in the old block. I can grasp that. That is, according to the present embodiment, it is possible to efficiently grasp the correspondence between the logical page and the physical page.

  If the first series of data is written and before the fourth series of data is written (that is, if no page management information is written), the physical block (the old block or When reading data from the new block), the memory controller 3 determines that the data is stored in the order of logical pages from the data corresponding to the first logical page, and grasps the correspondence between the logical page and the physical page. be able to.

  The above is the description of the second embodiment.

  The page management information is preferably a table indicating the correspondence between logical pages and physical pages as described above, but as a modification, the top data of each series of data written in the physical block LPN (hereinafter referred to as “SLPN”) of the logical page corresponding to, and the number of pages in which the series of data is written (the page count which is the number of pages from the page where the first data is written to the page where the last data is written) Value (hereinafter referred to as “PCNT”), it may be information indicating a physical block to which a physical page to which the series of data is written belongs. Furthermore, information indicating the physical page number (PPN) of the physical page in which the top data of each series of data is written may be added. When such information is written, a table indicating the correspondence between logical pages and physical pages is created based on this information.

  For example, FIGS. 11A to 11D show page management information # 0 ′ to # 3 ′, which are modifications of the page management information # 0 to # 3, respectively. In the page management information # 0 ′ to # 3 ′, the nth SLPN and PCNT set corresponds to the nth series of data. In the page management information # 2 ′ and 3 ′ written in the new block, an old block flag is associated with a set of SLPN and PCNT corresponding to a series of data written in the old block. For a portion where a series of data is written in the logical page order (LPN order) from the data corresponding to the first logical page to the physical page in the physical block, the portion corresponding to a plurality of series of data May be combined into one piece of information. For example, the portions corresponding to the first to third series of data may be combined into one, and SLPN may be # 0 and PCNT may be 32.

  In this modification, a table indicating the latest correspondence between logical pages and physical pages is created based on the latest page management information. Specifically, the records corresponding to the 64 logical page numbers (LPN) of LPN # 0 to # 63 are given priority in correspondence with the logical page and physical page corresponding to a series of data written later. The physical page number (PPN) is written. The correspondence relationship between the logical page and the physical page is grasped based on the set of SLPN and PCNT.

  For example, a table as shown in FIG. 10B is created based on the page management information # 3 ′. In this table creation, a physical page number (PPN) is written in each record based on the correspondence between the logical page and physical page corresponding to each series of data. The writing of the physical page number (PPN) is performed in order from the one corresponding to the previously written series of data. Even if the physical page number (PPN) is already written in the write destination record, the physical page number (PPN) is written later. The physical page number (PPN) is overwritten. Therefore, a table is created that prioritizes the correspondence between logical pages and physical pages corresponding to a series of data written later.

  As mentioned above, although several embodiment of this invention was described, these are the illustrations for description of this invention, Comprising: It is not the meaning which limits the scope of the present invention only to these embodiment. Of course, various modifications can be made without departing from the scope of the present invention.

  For example, in the above embodiment, the number of physical sector areas included in the logical block area and the physical block included in the logical block is the same. However, the number of logical sector areas included in the logical block may be smaller than the number of physical sector areas included in the physical block. In this way, even after data corresponding to all logical sector areas included in the logical block is stored in the physical block, the rewrite data of the data is changed to the empty area (data is written in the physical block). The data can be stored in a physical sector area or physical page that is not present. This makes it possible to efficiently rewrite data. For example, when the number of logical sector areas included in the logical block and the number of physical sector areas included in the physical block are both given by powers of 2, the number of logical sector areas included in the logical block Is 128, and the number of physical sector areas included in the physical block is 256.

  In addition, for example, the write process may end before the sector management information (page management information) is written due to power shutdown, so the divided redundant area 70 corresponding to the physical sector area 60 in which the sector management information has been written. It is preferable to write an end mark indicating that the writing process has ended normally in the common redundant area 50 of the physical page in which the page management information is written. In addition, when it is not necessary to write sector management information (page management information) (all physical sector areas 60 (physical pages) in which data in a physical block is written are logical in the logical block corresponding to the physical block). In the case of corresponding to the sector area (logical page) in order from the head), the divided redundant area 70 corresponding to the physical sector area 60 in which the end data of the series of data is written (the end data of the series of data is written). This end mark is written in the common redundant area 50) of the physical page.

1 is a block diagram showing a schematic configuration of a flash memory system according to a first embodiment of the present invention. It is a figure which shows the structure of the physical page of flash memory. It is a figure which shows the correspondence of a logical block and a physical block. FIG. 4A shows an example of a result of writing to the first half portion of 256 physical sector areas in the physical block. FIG. 4B shows an example of the result of writing to the latter half of the 256 physical sector areas in the physical block. FIG. 5A shows the contents of sector management information # 0 shown in FIG. FIG. 5B shows the contents of sector management information # 1 shown in FIG. FIG. 5C shows the contents of the sector management information # 2 shown in FIG. FIG. 6A shows the contents of sector management information # 3 shown in FIG. FIG. 6B shows the contents of the sector management information # 4 shown in FIG. FIG. 6C shows the contents of the sector management information # 5 shown in FIG. FIG. 7A shows a modification of the sector management information # 0 shown in FIG. FIG. 7B shows a modification of the sector management information # 1 shown in FIG. FIG. 7C shows a modification of the sector management information # 2 shown in FIG. FIG. 7D shows a modification of the sector management information # 3 shown in FIG. FIG. 7E shows a modification of the sector management information # 4 shown in FIG. FIG. 7F shows a modification of the sector management information # 5 shown in FIG. FIG. 8A shows an example of the result of writing to one physical block PBA # 7 assigned to the same logical block. FIG. 8B shows an example of the result of writing to the other physical block PBA # 16 assigned to the same logical block. FIG. 9A shows the contents of the page management information # 0 shown in FIG. FIG. 9B shows the contents of the page management information # 1 shown in FIG. FIG. 10A shows the contents of the page management information # 2 shown in FIG. FIG. 10B shows the contents of the page management information # 3 shown in FIG. FIG. 11A shows a modification of the page management information # 0 shown in FIG. FIG. 11B shows a modification of the page management information # 1 shown in FIG. FIG. 11C shows a modification of the page management information # 2 shown in FIG. FIG. 11D shows a modification of the page management information # 3 shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Flash memory system, 2 ... Flash memory, 3 ... Memory controller, 6 ... Microprocessor

Claims (11)

A memory controller that controls access to a flash memory that is erased in units of physical blocks including a plurality of physical sector areas, based on an access instruction given from a host system,
A block management means for managing a correspondence relationship between a logical block composed of a plurality of logical sector areas and the physical block;
Empty sector area search means for searching for the beginning of the physical sector area in which data in the physical block corresponding to the logical block to which the logical access area specified as the area to be accessed by the access instruction belongs is not written;
A series of data instructed to be written to the logical access area by the access instruction is transferred from the head physical sector area to which the data detected by the free sector area search means is not written, to the physical address at the end. Data writing means for sequentially writing toward the sector area;
Sector management information indicating a correspondence relationship between the physical sector area in the physical block in which the series of data is written by the data writing unit and the logical sector area in the logical block corresponding to the physical block, Sector management information writing means for writing in the physical sector area next to the physical sector area in which the end data of the series of data is written;
A memory controller comprising: The sector management information writing unit is configured to output the logical block corresponding to the physical block to all the physical sector areas in which data in the physical block in which the series of data has been written by the data writing unit is written. When the logical sector areas in the block correspond in order from the top, the sector management information is not written in the physical sector area next to the physical sector area in which the end data of the series of data is written,
The memory controller according to claim 1. The data stored in the physical sector area in the physical block corresponding to the logical block to which the logical access area specified by the access instruction belongs is changed to the end of the data in which the data in the physical block is written. Further comprising data reading means for reading based on the sector management information stored in the physical sector area,
The memory controller according to claim 1, wherein the memory controller is a memory controller. When the sector read information is not stored in the physical block corresponding to the logical block to which the logical access area belongs, the physical read area is written with data in the physical block. On the other hand, the logical sector area in the logical block corresponding to the physical block is considered to correspond in order from the top, and data is read.
The memory controller according to claim 3. A memory controller that controls access to a flash memory that is erased in units of physical blocks including a plurality of physical pages, based on an access instruction given from a host system,
Block management means for managing a correspondence relationship between a logical block composed of a plurality of logical pages and the physical block;
Empty page search means for searching for the top of the physical page in which data in the physical block corresponding to the logical block to which the logical access page designated as the logical page to be accessed belongs by the access instruction belongs,
A series of data instructed to be written to the logical access page by the access instruction is transferred from the first physical page to which the data detected by the empty page search unit is not written to the last physical page. Data writing means for sequentially writing toward the
Page management information indicating a correspondence relationship between the physical page in the physical block in which the series of data is written by the data writing unit and the logical page in the logical block corresponding to the physical block; Page management information writing means for writing to the physical page next to the physical page in which the end data of the data is written;
A memory controller comprising: The page management information writing unit includes the logical block corresponding to the physical block for all the physical pages in which data in the physical block in which the series of data has been written by the data writing unit is written. The page management information is not written to the physical page next to the physical page in which the end data of the series of data is written,
The memory controller according to claim 5. The data stored in the physical page in the physical block corresponding to the logical block to which the logical access page specified by the access instruction belongs is changed to the last physical in which the data in the physical block is written. Data reading means for reading based on the page management information stored in the page;
The memory controller according to claim 5, wherein the memory controller is a memory controller. When the page management information is not stored in the physical block corresponding to the logical block to which the logical access page belongs, the data reading means is stored in the physical page in which data in the physical block is written. On the other hand, it is assumed that the logical pages in the logical block corresponding to the physical block correspond in order from the top, and data is read.
The memory controller according to claim 7. A memory controller according to any one of claims 1 to 8,
And a flash memory system accessed by the memory controller. A flash memory control method in which erasure is performed in units of physical blocks including a plurality of physical sector areas based on an access instruction given from a host system,
A block management step for managing a correspondence relationship between a logical block composed of a plurality of logical sector areas and the physical block;
A free sector area search step for searching for the beginning of the physical sector area in which data in the physical block corresponding to the logical block to which the logical access area designated as the access target area by the access instruction belongs is not written;
A series of data instructed to be written to the logical access area by the access instruction is transferred from the first physical sector area to which the data detected in the free sector area search step is not written to the last physical sector. A data writing step of sequentially writing toward the sector area;
Sector management information indicating a correspondence relationship between the physical sector area in the physical block in which the series of data is written in the data writing step and the logical sector area in the logical block corresponding to the physical block, Sector management information writing step for writing to the physical sector area next to the physical sector area in which the end data of the series of data is written;
A method of controlling a flash memory, comprising: A flash memory control method in which erasure is performed in units of physical blocks including a plurality of physical pages based on an access instruction given from a host system,
A block management step for managing a correspondence relationship between a logical block composed of a plurality of logical pages and the physical block;
A free page search step of searching for the top of the physical page in which data in the physical block corresponding to the logical block to which the logical access page designated as the logical page to be accessed by the access instruction belongs is not written;
A series of data instructed to be written to the logical access page by the access instruction is transferred from the first physical page to which the data detected in the empty page search step is not written to the last physical page. A data writing step of sequentially writing toward the
Creating page management information indicating a correspondence relationship between the physical page in the physical block in which the series of data is written in the data writing step and the logical page in the logical block corresponding to the physical block; A page management information writing step for writing to the physical page next to the physical page in which tail data of the series of data is written;
A method of controlling a flash memory, comprising:

Images