JPH11191297A - High speed rewritable memory device using nonvolatile memory and method of rewriting data in said memory device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a rewrite time by executing a deleting operation of other memory blocks to be rewritten in next in parallel with writing operation into a certain memory block when plural consecutive data blocks are rewritten. SOLUTION: When it is confirmed that a writing data block D2 into a memory block 320 ended normally, a transfer processing 41 for transferring the data block D3 a buffer memory is executed (processing 10), and a transfer processing 43 for transferring the data D3 to a block 311 of a first rewritable nonvolatile memory (processing 11) and a write processing 44 (processing 12) for successively writing this data D3 into the memory block 311 are successively executed. A similar processing (processing 13-) are executed on the processing for rewriting a fourth data block D4 into a memory block 321. Hereafter, contents of memory blocks are sequentially rewritten. And, it is possible to execute an erase processing 42 in parallel with the write processing 44.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a storage device having a rewritable nonvolatile memory which requires an erasing operation at the time of rewriting stored data and a data rewriting method thereof, and more particularly to a data rewriting speed of the storage device. The present invention relates to a storage device that realizes improvement and a data rewriting method thereof.

[0002]

2. Description of the Related Art An electrically rewritable nonvolatile memory whose stored contents can be electrically rewritten and whose stored contents do not disappear even when the power is turned off is widely used mainly as a storage device of an information processing apparatus. In some rewritable nonvolatile memories, data is rewritten by performing a process of once erasing data and then writing new data. When rewriting data in such a procedure,
A two-stage operation of erasing data and writing data is required, and there is a problem that much time is required until complete rewriting is completed.

[0003] In order to solve such a problem, various techniques have been conventionally proposed. For example, JP-A-5-27
In the technology disclosed in Japanese Patent No. 924, the apparent rewriting speed is improved by providing a buffer memory for temporarily storing data before writing data to the rewritable nonvolatile memory.

[0004]

In order to improve the rewriting speed by providing a buffer memory for temporarily storing data as in the prior art, it is necessary to rewrite a plurality of rewritable nonvolatile memory chips at once. Becomes possible. That is, by temporarily sending the data stored in the buffer memory to a plurality of chips and executing the writing process at the same time, it is theoretically possible to reduce the time spent for writing to a fraction of the number of chips.

However, in order to operate many rewritable nonvolatile memories in parallel and write data stored in the buffer memories to a plurality of memory chips at the same time, more buffer memories are required. This is because, unless data written in the memory chip is left in the buffer memory until the writing is completed normally, if the writing fails, the written data is lost. In order to eliminate such a loss of write data, buffer memories for the number of chips for which write processing is performed are eventually required.

According to the above-mentioned method, in order to shorten the time for writing to a memory chip, the cost of the device increases, the size and weight of the device increase, and the power consumption increases with the increase of the buffer memory. Various adverse effects such as an increase are generated.

In view of the above problems, an object of the present invention is to provide a high-efficiency rewriting process in accordance with the characteristics of a memory chip without increasing the number of buffer memories so that the rewriting time is not increased. Is to shorten.

[0008]

In order to achieve the above object, the present invention has a rewritable nonvolatile memory that requires an erasing operation at the time of data rewriting, and stores data stored in the rewritable nonvolatile memory. In a storage device that handles rewriting processing in units of blocks, when rewriting a plurality of continuous data blocks, an erasing operation of another memory block to be rewritten next is executed in parallel with a writing operation to a certain memory block. I did it.

According to the present invention, there is provided a storage device having a rewritable nonvolatile memory which requires an erasing operation at the time of data rewriting, and performing a process of rewriting data stored in the rewritable nonvolatile memory in block units. A data storage unit for temporarily storing write data before writing data to the nonvolatile memory; and a part or all of the data stored in the data storage unit during rewriting of a plurality of continuous blocks. Data rewriting control means for executing a writing operation of a certain block by transferring the data to the non-volatile memory and erasing another block to be rewritten next.

Further, according to the present invention, in the above-mentioned storage device, if the memory block to which the data is written is defective and the writing is not completed normally, the data stored in the data storage means is transferred to another block. To execute the writing process.

The present invention is directed to a storage device having a rewritable nonvolatile memory which requires an erasing operation at the time of data rewriting, and performing a process of rewriting data stored in the rewritable nonvolatile memory in block units. Data storage means for temporarily storing write data before writing data to the nonvolatile memory; rewritable nonvolatile memory erasing means for erasing a specific memory block of a specific chip of the rewritable nonvolatile memory; A data writing unit that transfers data stored in the data storage unit to a specific memory block of a specific chip of the rewritable nonvolatile memory and writes the data; and controls the memory erasing unit and the data writing unit. Rewriting control means for storing the data of one or more memory blocks in the rewritable nonvolatile memory; When rewriting the memory block with a block, the rewrite control means (1) stores the data to be rewritten in the data storage means and simultaneously erases the contents of the memory block of the rewritable nonvolatile memory to be rewritten. (2) The data stored in the data storage means is transferred to the memory block of the rewritable nonvolatile memory in which the erasing is completed, and the writing is performed, and at the same time, the next rewriting in another chip in which the writing is not performed is performed. Control for erasing the memory block to be performed (3) Control for storing the data to be written next in the data storage means when the writing is completed normally (4) Hereinafter, until all rewriting of a plurality of continuous memory blocks is completed The control for repeatedly executing the processes (2) and (3) is executed.

According to another aspect of the present invention, there is provided a rewritable nonvolatile memory which requires an erasing operation at the time of data rewriting, and a process for rewriting data stored in the rewritable nonvolatile memory. In a data rewriting method of a storage device handled in units, when rewriting a plurality of continuous data blocks, an erasing operation of another memory block to be rewritten next is executed in parallel with a writing operation to a certain memory block. .

According to the present invention, there is provided a rewritable nonvolatile memory which requires an erasing operation at the time of data rewriting, a data storage means, and a data rewriting control means, and performs a process of rewriting data stored in the rewritable nonvolatile memory. In the data rewriting method for a storage device that handles block units, write data is temporarily stored in a data storage unit before writing data to the rewritable nonvolatile memory, and when rewriting a plurality of continuous blocks, the data storage unit stores the write data. A part or all of the stored data is transferred to the rewritable nonvolatile memory to execute a write operation of a certain memory block, and in parallel with this write operation, another block to be rewritten next Execute the deletion of

According to the present invention, in the above data rewriting method for a storage device, the data stored in the data storage means is transferred to another block when the written memory block is defective and the writing is not completed normally. And execute the writing process.

According to the present invention, there is provided a rewritable nonvolatile memory which requires an erasing operation when rewriting data, a data storage means,
A data rewriting method for a storage device having a rewritable nonvolatile memory erasing unit, a data writing unit, and a rewriting control unit, and performing a process of rewriting data stored in the rewritable nonvolatile memory in block units. Before writing data in the rewritable nonvolatile memory, the write data is temporarily stored in the data storage means, and the data to be rewritten is stored in the data storage means, and at the same time, the rewritable nonvolatile memory to be rewritten is Erasing the memory block of the volatile memory, transferring the data stored in the data storage means to the memory block of the rewritable nonvolatile memory that has been erased, and writing the data simultaneously with another chip in which the writing has not been performed. The contents of the memory block to be rewritten next are erased, and the data to be written next is written when writing is completed normally. Stored in the data storage means.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a storage device according to the present invention will be described with reference to the drawings. FIG. 1 shows a configuration example of a storage device for implementing the present invention. In FIG. 1, a storage device 1 having a rewritable nonvolatile memory includes a control unit 10 that controls each unit of the storage device 1 and an interface with a host system, and a plurality of rewritable nonvolatile memories 30.
And a buffer memory 20 for temporarily storing data. The buffer memory 20 is connected to a host system (not shown) via the system bus 2. Further control means 1
0 indicates rewriting control means 11 and non-volatile memory erasing means 1
2 and data writing means 13.

The control means 10 controls each section of the storage device 1 and an interface with the host system. The buffer memory 20 exchanges data between the host system and the rewritable nonvolatile memory, including the rewriting of the rewritable nonvolatile memory 30 by the host system, and moves data stored in the rewritable nonvolatile memory 30. In this case, it works as a data storage means for temporarily storing data. The rewritable nonvolatile memory 30 is configured using, for example, a rewritable nonvolatile memory including an electrically rewritable ROM. The system bus 2 is used to exchange data and control signals with a host system (not shown).

The rewriting means 11 achieves a rewriting control function of controlling the rewritable nonvolatile memory erasing means 12 and the data writing means 13 to store one or more blocks of data in the rewritable nonvolatile memory 30. The rewritable nonvolatile memory erasing means 12 achieves a rewritable nonvolatile memory erasing function for erasing a specific memory block of a specific chip of the rewritable nonvolatile memory 30. Data writing means 13
Achieves a data write function of writing data by transferring data stored in the buffer memory 20 to a specific memory block of a specific chip of the rewritable nonvolatile memory 30.

The system bus 2 is provided on the host system side. When the host system sends a data access request to the storage device 1 via the system bus 2, the control means 10 in the storage device 1 that has received the request requests the rewritable nonvolatile memory storing the data corresponding to the content of the access request. A physical position (memory block) on the memory 30 is determined, and the buffer memory 20 is used as needed to respond to a host access request.

Referring to FIG. 2, the path of data written to the rewritable nonvolatile memory 30 in the storage device 1 shown in FIG. When rewriting data stored in a memory block in each rewritable nonvolatile memory, rewriting is performed at once in units of a group of data. Hereinafter, the unit of the storage area in the rewritable nonvolatile memory that is rewritten for each rewrite unit is referred to as a memory block. The rewritable nonvolatile memory 30 includes a plurality of rewritable nonvolatile memories 31 and 32. Each of the rewritable nonvolatile memories 31 and 32 has a plurality of memory blocks 310, 311 to 320, 321 to 321.
Are arranged in order.

The buffer memory 20 is the same as the buffer memory 20 shown in FIG. 1, but here is a transfer buffer memory functioning particularly as a data buffer used for data transfer. The transfer buffer memory 20 and the rewritable nonvolatile memories 31 and 32 are connected via the data bus 14. Through this data bus 14, the rewritable nonvolatile memories 31, 32 are transferred from the buffer memory 20.
Transfer data to The system bus 2 includes a control unit 1
0 also serves as a data bus of the system, and can be said to be a local bus of the storage device 1.

FIG. 2 shows an example in which the control means 10 controls the two rewritable nonvolatile memories 31 and 32. Generally, the rewritable nonvolatile memory controlled by the control means 10 has two rewritable nonvolatile memories. The number does not need to be one, and may be further increased.

For example, as shown in FIG. 3, three rewritable nonvolatile memories 31 and 3 are connected through an internal data bus 14.
2, 33 can be connected in parallel. In this way, by increasing the number of rewritable non-volatile memories to be processed in parallel, it becomes possible to execute more writing processing to the memory chip in parallel, so that writing performance can be improved. .

The order of the data rewriting process in the rewritable nonvolatile memory by the storage device 1 shown in FIGS. 1 and 2 will be described with reference to FIG. In the figure, the upper part shows the processing for the rewritable nonvolatile memory 31, and the lower part shows the processing for the rewritable nonvolatile memory 32. Each process includes a transfer process 41 for transferring one block of data (hereinafter, referred to as a data block) from the system bus 2 to the transfer buffer memory 20 and a process already written in the memory blocks in the rewritable nonvolatile memories 31 and 32. Erasing processing 42 for erasing data stored therein, transfer processing 43 for transferring data of one data block from the buffer memory 20 to the rewritable nonvolatile memories 31 and 32 through the data bus 14, and rewritable nonvolatile memories 31 and 32.
There is a write process 44 for writing the data transferred to the respective memory blocks, and the time required for each process is indicated by its length. Note that transfer processing 41 to rewrite processing 4
The time width of 4 is not shown in proportion to the actual time required. Further, the processing times of the transfer processing 41 to the rewriting processing 44 are not always constant. Furthermore, “writing” means storing new data in the erased block, and “rewriting” is completed by executing “writing” after executing “erasing”.

First, data D ₁ -D of two or more continuous data blocks are sent from the host system to the storage device 1.
Consider a case where an n rewrite request has occurred. A transfer process 41 for storing the data D ₁ of the first block in the transfer buffer memory 20 via the system bus 2 is executed (process 1). The control unit 10 determines a physical position (memory block) of a memory block to be replaced with data currently stored in the buffer memory 20. In this embodiment, it is assumed that the replaced memory block 310 is in the first rewritable nonvolatile memory 31. The control means 10 issues a command to the first rewritable nonvolatile memory 31 to execute an erasing process 42 for erasing the data D _00-1 already stored in the block 310 (process 2).

After confirming that the data erasure by the process 2 has been completed, the control means 10 executes a transfer process 43 for transferring the data D ₁ in the buffer memory 20 to the rewritable nonvolatile memory 31 (process 3). Subsequently, the write processing 44 for writing the data D ₁ into the memory block 310
Is executed (process 4). Control means 10, the processing 4 holds without erasing the data D ₁ of the buffer 20 until confirms that completely finished. By doing so, the transfer process 43 of process 3 or the write process 44 of process 4
During the execution, even with some error in the storage device 1 is generated and interrupted writing operation, the data D ₁ it is possible to rewrite the rewritable nonvolatile memory again because it is stored in the buffer 20 .

The control means 10 controls the first data block D
Write process 44 to ₁ memory block 310 (process 4)
Until the end of the process, the physical position of the memory block 320 to be rewritten second is determined, and the data D _00-2 already stored in this memory block is erased.
2 is executed (process 5). Here, consecutive memory blocks are alternately allocated to the first rewritable nonvolatile memory 31 and the second rewritable nonvolatile memory 32 in advance. By doing so, the memory block to be rewritten next can be erased in parallel with the writing process to one memory block.

When the writing of the data block D ₁ to the first memory block 310 ends normally, a transfer process 41 for transferring the data D ₂ to the second memory block 320 through the system bus 2 to the buffer memory 20 is executed. (Process 6). Unlike the writing to the first block 310, the erasure of the data _D00-2 already stored in the memory block 320 to be written has already been completed.
A transfer process 43 for immediately transferring the content D ₂ of the buffer memory 20 to the memory block 320 of the second rewritable nonvolatile memory 32 can be executed (process 7), and subsequently, the data D _{2 is transferred} to the memory block 320. Is executed (process 8). Until the writing process 44 in the process 8 completely, the data D ₂ in the buffer memory 20 holds without erasing.

By the end of the write process 44 (process 8) of the memory block 320, the control means 10 determines the physical position of the memory block 311 to be rewritten thirdly, and the physical position of the memory block 311 that has already been stored in this block is determined. Data D _01-1
Is executed (step 9). When the write data block D ₂ in the memory block 320 to verify that successful, the buffer memory 20
To perform the transfer process 41 to transfer the data block D ₃ (process 10), the transfer processing 4 that transfers data D ₃ to the memory block 311 of the first rewritable non-volatile memory 31
1 (process 11), subsequently and sequentially executes the write process 43 (process 12) for writing the data D ₃ to the memory block 311. Similar processing (processing 13 to) is performed for the processing of rewriting the _fourth data block D4 to the memory block 321. Hereinafter, the memory blocks 322 are sequentially
Is rewritten.

By the above processing, in the ordinary simple rewriting processing, the data D _{1 for} four blocks shown in FIG.
When writing to D ₄ is, rewritable nonvolatile memory 3
0 is erased four times and the rewritable nonvolatile memory 30
Write processing 44 to the buffer memory 20
The data transfer process 41 to the non-volatile memory 30 and the data transfer process 43 to the non-volatile memory 30 need to be executed a total of eight times. As is apparent from FIG. Therefore, the erasing process 42 of the rewritable nonvolatile memory 30 is performed four times, the writing process 44 to the rewritable nonvolatile memory 30 is performed once, and the data transfer processes 41 and 43 are performed eight times in total. It is possible to execute a series of data rewriting processes in the execution time. Then, the transfer buffer memory 20 required to execute this processing needs only the capacity of one data block.

Referring to FIG. 5, a storage device 1 according to the present invention will be described.
Another embodiment will be described. The storage device 1 according to this embodiment includes a first rewritable nonvolatile memory 31 and a third rewritable nonvolatile memory 3 divided into a plurality of groups.
3, a second rewritable nonvolatile memory 32, a fourth rewritable nonvolatile memory 34, and a first storage unit capable of storing data having a capacity of one data block.
Buffer memory 201 and second buffer memory 2
02, a first buffer memory 201, and a first rewritable nonvolatile memory 31.
And a data bus 141 connecting the third rewritable nonvolatile memory 33 and a data bus 142 connecting the second buffer memory 202 to the second rewritable nonvolatile memory 32 and the fourth rewritable nonvolatile memory 34. Composed,
It is connected via a system bus 2 to a host system (not shown).

Each of the rewritable nonvolatile memories 31 to 34 has a plurality of memory blocks 310, 311 to 31,
320, 321 to 330, 331 to 340, 341
Is provided.

FIG. 6 shows the order of processing when a rewriting operation is performed in the storage device 1 having the configuration shown in FIG. FIG.
3 is characterized in that two buffer blocks can be simultaneously rewritten by adding one buffer memory compared to the storage device 1 shown in FIG. . In the figure, the upper part shows the processing for the first rewritable nonvolatile memory 31 and the second rewritable nonvolatile memory 32, and the lower part shows the third rewritable nonvolatile memory 33 and the fourth rewritable nonvolatile memory 34. Shows the processing for.

Each process includes a transfer process 41 for transferring data of one data block from the system bus 2 to the first buffer memory 201 and the second buffer memory 202 of the transfer buffer memory 20, respectively, and a rewritable nonvolatile memory. Memory 31, 32 or rewritable nonvolatile memory 3
An erasing process 42 for erasing data written in each memory block in each of the memory blocks 3 and 34; and a first rewritable nonvolatile memory 31 or a third rewritable memory The second buffer memory 202 is connected to the memory block of the rewritable nonvolatile memory
A transfer process 43 for transferring data of one data block to each of the memory blocks of the rewritable nonvolatile memory 32 or the fourth rewritable nonvolatile memory 34, and transferring the data transferred to the rewritable nonvolatile memories 31 to 34. There is a write process 44 for writing to each memory block, and the time required for each process is indicated by its length.

Note that the width of the processing time of the transfer processing 41 to the rewriting processing 44 is not necessarily shown in proportion to the actual time required. Further, the processing time of the transfer processing 41 to the rewrite processing 44 is not always constant. Furthermore, “writing” means storing new data in the erased block, and “rewriting” is completed by executing “writing” after executing “erasing”.

It is assumed that a request for rewriting data D _{1 to} Dn of four or more consecutive blocks to the storage device 1 is issued from the host system. First, the data D ₁ of the first block and the data D ₂ of the second block are transferred to the system bus 2.
Through the first buffer memory 2 of the buffer memory 20
01 and the transfer process 41 stored in the second buffer memory 202 is executed (process 1). At this time, the data D ₁ of the first data block is stored in the first buffer memory 201 and the data D ₂ of the second data block is stored in the second buffer memory 2.
02 is stored.

The control means 10 includes the current buffer memory 20
Determine the physical location of the memory block that will be replaced with the data stored in. Here, it is assumed that the replaced memory blocks are the memory block 310 in the first rewritable nonvolatile memory 31 and the memory block 320 in the second rewritable nonvolatile memory 32.
The control means 10 issues a command to the first rewritable nonvolatile memory 31 and the second rewritable nonvolatile memory 32, and outputs data (D _00-1 , D ₀₀ ) already stored in the memory blocks 310, 320. _00-2 ) is erased (process 2).

After confirming that the data erasure of the memory block to be rewritten has been completed, the control means 10 allows the data D ₁ in the first buffer memory 201 of the buffer memory 20 to be first rewritten via the data bus 141. The data D ₂ in the second buffer memory 202 of the buffer memory 20 is stored in the memory block 310 of the nonvolatile memory 31.
Processing 4 for transferring data to the memory block 320 of the second rewritable nonvolatile memory 32 via the data bus 142.
3 (process 3), and subsequently each data D
_1, executes the write process 44 writes D ₂ to the respective memory blocks (process 4).

The control means 10 operates the buffer 20 until it confirms that the processing of writing the data D ₁ and D ₂ into the memory blocks 310 and 320 (processing 4) has been completed.
The data D ₁ and D ₂ in the first buffer memory 201 and the second buffer memory 202 are held without being erased. By doing so, even if any error occurs in the storage device 1 and the rewriting operation is interrupted during the execution of the transfer process 43 (process 3) or the write process 44 (process 4), rewriting can be performed again. Become.

By the end of the write process 44 (process 4) of the first two data blocks of data D ₁ and D ₂ , the control means 10 controls the third rewritable nonvolatile memory 33 to be rewritten next and The physical positions of the memory blocks 330 and 340 of the fourth rewritable nonvolatile memory 34 are determined,
The data already stored in this memory block (D
_00-3 , D _00-4 ) is erased (process 5). Here, consecutive memory blocks are always allocated in order from the first rewritable nonvolatile memory 31 to the fourth rewritable nonvolatile memory 34. By doing so, the block to be rewritten next can be erased in parallel with the writing process.

When the writing of the data D ₁ and D ₂ to the first two memory blocks 310 and 320 ends normally, the data D ₃ and D ₄ for rewriting the two memory blocks 330 and 340 to be rewritten next are transferred to the system bus 2. Transfer processing 41 for transferring the data to the first buffer memory 201 and the second buffer memory 202 of the buffer memory 20 through the process (process 6). Unlike the first memory blocks 310 and 320, the erasure of the data in the memory blocks 330 and 340 to be written has already been completed this time, so the first buffer memory 201 and the second buffer memory 202 of the buffer memory 20 are immediately D ₃ and D ₄ temporarily stored in
Is transferred to the memory block 330 of the third rewritable nonvolatile memory 33 and the memory block 340 of the fourth rewritable nonvolatile memory 34 (process 7), and subsequently, the data D ₃ , writing process 44 which writes each D ₄ to the memory blocks 330 and 340
Is executed (process 8). Until the write process 44 (process 8) is completed, the first buffer memory 201 and the second buffer memory 202 of the buffer memory 20
The data D ₃ and D ₄ temporarily stored in the memory are kept without being erased.

By the time the rewriting process 44 (process 8) is completed, the control means 10 sets the data (D) already stored in the memory blocks 311 and 321 to be rewritten next.
_01-1 and _D01-2 ) are erased (process 9).

When it is confirmed that the rewrite process 44 (process 8) for the memory blocks 330 and 340 has been completed normally, the first buffer memory 201 of the buffer memory 20 is checked.
And data D to the second buffer memory 202, respectively.
_5, the D ₆ performs the transfer process 41 to transfer (process 10),
Memory block 3 of first rewritable nonvolatile memory 31
11 and a transfer process 43 for transferring data D ₅ and D ₆ to the memory block 321 of the second rewritable nonvolatile memory 32.
(Process 11) and a write process 44 for writing data D ₅ and D ₆ to the memory blocks 311 and 321 (Process 12)
Are sequentially executed. Similar processing is performed for rewriting of the subsequent blocks 331 and 341.

In the example of FIG. 5, not only the parallel processing of the rewriting operation is enabled by the increase of the buffer memory, but also the remaining two rewritable nonvolatile memories are written at the time of the writing operation to the two rewritable nonvolatile memories. By executing the memory erasure in parallel, the data rewriting speed can be further improved.

Referring to FIG. 7, an embodiment in which the time required for erasing processing 42 is longer than the time required for writing processing 44 will be described. In this embodiment, a rewritable nonvolatile memory includes first to eighth eight memory chips, a buffer memory having a storage capacity for two data blocks,
It is assumed that the time required for the erasing process 42 is about four times the time required for the writing process 44. First, a transfer process 41 for transferring data D ₁ and D ₂ for two data blocks to the buffer memory is executed (process 1). Next, an erasing process 42 for erasing the contents of all the rewritable nonvolatile memory chips.
Is executed (process 2). Next, the first data block 310 of the rewritable non-volatile memory 31 performs the transfer process 43 to transfer data D ₁ (process 3), the writing process 4 continue writing data D ₁ to the memory block 310
4 is executed (process 4). Subsequently, the memory block 320 of the second rewritable non-volatile memory 32 to perform the transfer process 43 to transfer data D ₂ together (processing 5),
Memory block 3 of second rewritable nonvolatile memory 32
Executing the write process 44 to write data D ₂ to the 20 (process 6).

After confirming that the writing process of process 4 and the writing process of process 6 have been completed normally, the third rewritable nonvolatile memory 33 and the fourth rewritable nonvolatile memory 3
For write data D _3, D ₄ to 4, transfer process subjected to the transfer of data D _3, D ₄ from the host system 4
1 is executed (processing 7 and processing 8).

At this time, the first rewritable nonvolatile memory 31 and the second rewritable nonvolatile memory 32 execute an erasing process 42 for erasing the memory blocks 311 and 321 to be written next (process 9). , Processing 10).

For the third rewritable nonvolatile memory 33 and the fourth rewritable nonvolatile memory 34, as soon as the processing 5 and the processing 6 are completed, the memory blocks 330 and 34
A transfer process 43 for transferring the data D ₃ and D ₄ to 0 is executed (process 11 and process 12), and subsequently, a write process 44 for writing the data D ₃ and D ₄ to the memory block is executed (process 13 and process). 14). Further, a third rewritable nonvolatile memory 33 and a fourth rewritable nonvolatile memory 34
Then, if there is a data block to be written next, an erasing process 42 for erasing data in the memory blocks 331 and 341 is executed (processes 15 and 16).

Hereinafter, the fifth rewritable nonvolatile memory 35 will be described.
The same processing is performed thereafter. At this time, the processing 9 and the processing 10 as the erasing processing 42 for erasing the memory block 311 of the first rewritable nonvolatile memory 31 and the memory block 321 of the second rewritable nonvolatile memory 32 are compared with the writing processing. Since about four times longer time is required, the erasure ends when the writing of the data D ₇ and D ₈ to the seventh and eighth rewritable nonvolatile memories 37 and 38 ends.
The writing process can be executed immediately. Hereinafter, the memory blocks 36 of the other rewritable nonvolatile memories 36 to 38 will be described.
Similar processing is performed for 0, 361 to 380, and 381 to 38n, and a very efficient rewriting process can be realized.

In the above-described embodiment, all the writing processes succeed and the process can proceed to the next process. However, if the writing process ends in failure, the data is stored in the buffer memory. By temporarily transferring the stored data to another memory block and executing the writing process again from this memory block, the writing process can be executed any number of times until the writing is successful.

[0051]

According to the present invention, in a storage device using an electrically rewritable non-volatile memory which requires an erasing process in block units as a storage medium, it is required to perform high-speed rewriting. By using a storage buffer having a smaller number of blocks than the number of chips to be mounted, it is possible to realize a rewriting performance almost equal to that in a case where a buffer having the same number of blocks as the number of chips to be mounted is provided. In addition, at this time, even if the writing fails, the writing process can be executed any number of times until the writing succeeds without losing the write data. Further, in the case of using a nonvolatile memory in which the time required for erasing is longer than the time for writing data in the same area, the writing process and the erasing process can be executed efficiently, The rewriting process can be realized at high speed with a small buffer memory.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of a configuration of a storage device that implements the present invention.

FIG. 2 is a first data path in the storage device shown in FIG. 1;
The block diagram which shows the example of.

FIG. 3 shows a second data path in the storage device shown in FIG. 1;
The block diagram which shows the example of.

FIG. 4 is a diagram (1) illustrating an order of processing when data rewriting is performed in parallel by the storage device illustrated in FIGS. 1 and 2;

FIG. 5 illustrates a third data path in the storage device illustrated in FIG. 1;
The block diagram which shows the example of.

FIG. 6 is a diagram (2) illustrating an order of processing when data rewriting is performed in parallel by the storage device illustrated in FIGS. 1 and 5;

FIG. 7 is a diagram showing the order of processing for rewriting data at high speed when a memory having a longer erasing time than a writing time is used.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Storage device 2 System bus 10 Data rewriting control circuit 11 Rewriting control means 12 Memory erasing means 13 Data writing means 14, 141, 142 Data bus 20 Buffer memory 30 Rewritable nonvolatile memory 31 First rewritable nonvolatile memory 32 Second rewritable nonvolatile memory 33 Third rewritable nonvolatile memory 34 Fourth rewritable nonvolatile memory 41 Data transfer processing between system bus and buffer memory 42 Data erasing processing of rewritable nonvolatile memory 43 Buffer memory Data transfer processing between rewritable nonvolatile memories 44 Data writing processing of rewritable nonvolatile memory 201 First buffer memory 202 Second buffer memory 310, 311, 320, 321, 330, 331 Memory block

Continued on the front page (72) Inventor Takashi Totsuka 5-2-1, Josuihonmachi, Kodaira-shi, Tokyo In the semiconductor division of Hitachi, Ltd.

Claims (8)

[Claims] 1. A storage device having a rewritable non-volatile memory which requires an erasing operation at the time of data rewriting and handling a process of rewriting data stored in the rewritable non-volatile memory in units of blocks, A storage device characterized in that, when a block is rewritten, an erasing operation of another memory block to be rewritten next is executed in parallel with a writing operation to a certain memory block. 2. A storage device having a rewritable nonvolatile memory which requires an erasing operation at the time of data rewriting and handling a process of rewriting data stored in the rewritable nonvolatile memory in units of blocks, A data storage unit for temporarily storing write data before writing data to a memory; and a rewritable nonvolatile memory for partially or entirely storing data stored in the data storage unit when rewriting a plurality of continuous blocks. A data rewrite control means for executing a write operation of a certain block by transferring the data to another block and erasing another block to be rewritten next. 3. The storage device according to claim 2, wherein the data stored in the data storage means is transferred to another block if the memory block to which the data has been written is defective and writing has not been completed normally. A storage device for transferring and executing a writing process. 4. A storage device comprising a rewritable nonvolatile memory which requires an erasing operation at the time of data rewriting and handling a process of rewriting data stored in the rewritable nonvolatile memory in block units. Data storage means for temporarily storing write data before writing data to the memory; rewritable nonvolatile memory erasing means for erasing a specific memory block of a specific chip of the rewritable nonvolatile memory; Data writing means for transferring data stored in the means to a specific memory block of a specific chip of a rewritable nonvolatile memory for writing, controlling the memory erasing means and the data writing means, and Rewriting control means for storing the data of the above memory block in the rewritable nonvolatile memory; When the memory block is rewritten by the memory, the rewriting control means (1) stores the data to be rewritten in the data storage means and simultaneously erases the contents of the memory block of the rewritable nonvolatile memory to be rewritten. (2) The data stored in the data storage means is transferred to the memory block of the erasable rewritable non-volatile memory for which the erasure has been completed, and at the same time, the data is written to the memory block. Control for erasing a memory block to be executed (3) A storage device which executes control for storing data to be written next in data storage means when writing is completed normally. 5. A data rewriting method for a storage device having a rewritable non-volatile memory which requires an erasing operation at the time of data rewriting and handling a process of rewriting data stored in the rewritable non-volatile memory in block units. A method of rewriting a plurality of data blocks, the method further comprising performing, in parallel with a writing operation to a certain memory block, an erasing operation of another memory block to be rewritten next. 6. A rewritable nonvolatile memory which requires an erasing operation at the time of data rewriting, a data storage means, and a data rewriting control means, wherein a process of rewriting data stored in the rewritable nonvolatile memory is performed in block units. In the data rewriting method of the storage device handled in the above, the write data is temporarily stored in the data storage means before the data is written in the rewritable nonvolatile memory, and the data is stored in the data storage means at the time of rewriting a plurality of continuous blocks. A part or all of the data is transferred to the rewritable nonvolatile memory, and a write operation of a certain memory block is executed. In parallel with this write operation, another block to be rewritten next is erased. A data rewriting method for a storage device. 7. A data rewriting method for a storage device according to claim 6, wherein the data stored in the data storage means is separated when the memory block to which the data has been written is defective and the writing is not completed normally. A data rewriting method for a storage device, wherein the data is rewritten to a block of a storage device and a writing process is executed. 8. A rewritable nonvolatile memory which requires an erasing operation at the time of data rewriting, a data storage means, a rewritable nonvolatile memory erasing means, a data writing means, and a rewriting control means. In a data rewriting method of a storage device which handles a process of rewriting data stored in a nonvolatile memory in units of blocks, temporarily storing write data in the data storage means before writing data to the rewritable nonvolatile memory. The data to be rewritten is stored in the data storage means, and at the same time, the memory block of the rewritable nonvolatile memory to be rewritten is erased, and the data is stored in the memory block of the erased rewritable nonvolatile memory. At the same time as writing data by transferring the data stored in the A data rewriting method for a storage device, wherein the contents of a memory block to be rewritten are erased, and when the writing is normally completed, data to be written next is stored in the data storage means.