JPH11305954A - Semiconductor memory device and reloading control method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten time required for a processing corresponding to a reloading instruction. SOLUTION: A semiconductor disk device is constituted by providing a host interface 12, a microcontroller 14, a buffer memory 16, a storage medium 18 and a block position managing part 20. The storage medium 18 is equipped with plural sets (N sets) of a pair of semiconductor memory chips. When a reloading instruction is inputted to one semiconductor memory chip, data in all sectors consisting of a block including the sector of a reloading object are transferred to the buffer memory 16. In the buffer memory 16, the data in the sector of the reloading object are reloaded, and data transferred to the buffer memory 16 are transferred to the block in the erased area of the other semiconductor memory chip.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductor memory device and a method for controlling rewriting of the semiconductor memory device.

[0002]

2. Description of the Related Art Conventionally, there has been proposed a semiconductor disk device using a nonvolatile semiconductor memory such as a flash memory which retains stored information even when the power is turned off as an auxiliary storage device of a main storage device. . FIG. 14 (A)
As shown in FIG. 1, the semiconductor disk device is configured to include a host interface 12, a microcontroller 14, a buffer memory 16, and a storage medium 15 composed of a flash memory.

[0003] A microcontroller 14 controls data transfer between the host and the semiconductor disk device via the host interface 12.

As shown in FIG. 14B, the storage medium 15 is provided with a plurality of (for example, eight) blocks composed of a plurality of (for example, eight) sectors 30A to 30H, and the erasing operation is performed in block units. . One sector is a minimum unit for performing data rewriting or the like.
It is composed of 12 bytes.

The operation of the semiconductor disk device when a data rewrite command is output from the host will be described with reference to FIG.

[0006] When a data rewrite command output from the host is input, the microcontroller 14 calculates a sector to be rewritten. That is, it specifies in which block of the storage medium 15 the sector to be rewritten exists.

Next, the data of all the sectors 30A to 30H constituting the block including the sector to be rewritten is transferred to the buffer memory 16. As a result, the data of the block including the sector to be rewritten is read and written to the buffer memory 16. All sectors 30A to 30H constituting a block including the sector to be rewritten
Is transferred to the buffer memory 16, the data in the sector to be rewritten in the buffer memory 16 is rewritten according to the instruction from the host.

Subsequently, the data in the block of the storage medium 15 to which the data has been transferred to the buffer memory 16 is erased. In the storage medium 15, since the erasing operation is performed in units of blocks, for example, one block has eight sectors 30A to 3A.
In the case of 0H, data for 8 sectors is simultaneously erased.

Further, the data transferred to the buffer memory 16 is transferred to a corresponding block of the storage medium 15. That is, the data is transferred again to the block from which the data has been erased.
As a result, the data of the block including the sector whose data has been rewritten is rewritten.

[0010]

However, in the prior art, prior to re-transferring the data of the block including the sector whose data has been rewritten in the buffer memory, the data of the block as the transfer destination is temporarily erased. Then you have to transfer. As a result, there is a problem that it takes a long time to process a data rewrite instruction.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a semiconductor memory device and a semiconductor memory device rewrite control method which can reduce the time required for processing a rewrite instruction. I do.

[0012]

According to a first aspect of the present invention, there is provided a semiconductor memory device comprising: a pair of semiconductor storage media capable of erasing data in units of blocks each including a plurality of sectors; A block position management unit that stores block position management information indicating a block position of data stored in the semiconductor storage medium, a buffer memory that temporarily stores data, and a rewrite command for a sector of one semiconductor storage medium are input. In this case, the block position including the sector to be rewritten is determined based on the block position management information of the block position management unit, and the data in the buffer memory of the block including the sector to be rewritten of the one semiconductor storage medium is written to the buffer memory. Transfer, rewriting of data in a sector to be rewritten based on a rewrite instruction, Square of the transfer of data to the erased block of the semiconductor storage medium, and has a control unit for controlling the erasure of data in block units in the one semiconductor storage medium.

In the semiconductor storage medium according to the first aspect of the present invention, data can be erased in units of a block composed of a plurality of sectors. A flash memory can be used as the semiconductor storage medium. Further, the semiconductor storage device includes a block position management unit that stores block position management information indicating a block position of data stored in the semiconductor storage medium, and a buffer memory that temporarily stores data. The block position management unit stores block position management information in which each data is stored. The data temporarily stored in the buffer memory includes data related to a rewrite command (for example, a command, a sector number to be rewritten, rewrite data, etc.) and data stored in a semiconductor storage medium.

Further, the semiconductor memory device is provided with a control unit for controlling a process for the rewrite command when a rewrite command for a sector of one semiconductor storage medium of the pair of semiconductor storage media is input. The control unit determines the block position including the sector to be rewritten based on the block position management information of the block position management unit, and transfers the data to the buffer memory of the block including the sector to be rewritten in one semiconductor storage medium, Rewriting of data in a sector to be rewritten based on a rewriting instruction, transfer of data from the buffer memory to an erased block of the other semiconductor storage medium, and transfer of data in block units transferred from one semiconductor storage medium to the buffer memory. It controls erasure and the like.

According to the first aspect of the present invention, when rewriting data, data can be read from one semiconductor storage medium, the data can be rewritten in the buffer memory, and the rewritten data can be transferred to the other semiconductor storage medium. The time required for processing the data rewrite instruction from the server can be reduced.

According to a second aspect of the present invention, in the first aspect of the present invention, there is further provided an erased block control means for performing equalization of the number of the erased blocks in the pair of semiconductor storage media. It is characterized by. The erased block control means may be provided in the control unit of the first aspect of the present invention, or may be provided separately from the control unit.

When a rewrite command for a sector of one semiconductor storage medium of a pair of semiconductor storage media is continuously input, for example, the erased block to which the data of the block including the sector to be rewritten is to be transferred is replaced by the other. May not be present in the semiconductor storage medium. In this case, data transferred from one semiconductor storage medium to the buffer memory cannot be transferred to the other semiconductor storage medium.
Therefore, the semiconductor memory device according to the second aspect of the present invention includes:
Erased block control means for equalizing the number of erased blocks in a pair of semiconductor storage media is provided.

The erased block control means transfers the data of the block of the other semiconductor storage medium in which the erased block does not exist to the erased block of the one semiconductor storage medium, and thereafter transfers the data of one semiconductor storage medium of the other semiconductor storage medium. The data of the block whose data has been transferred to the medium is erased in block units to generate an erased block. This makes it possible to equalize the number of erased blocks.

A third aspect of the present invention is characterized in that, in the second aspect of the present invention, the number of erased blocks is equalized when an idle state for a predetermined time or more is recognized.

When the number of erased blocks is equalized after the rewrite instruction is input, the processing for the input rewrite instruction is interrupted during the execution of the equalization. Therefore, in the invention according to claim 3, when the idle state for a predetermined time or more is recognized, that is, when the host does not access the semiconductor memory device for the predetermined time or more, the number of erased blocks is equalized. Execute. That is, the number of erased blocks is equalized before the rewrite command is input. Thus, the processing for the rewrite instruction can be performed without interrupting the processing for the rewrite instruction.

According to a fourth aspect of the present invention, when a rewrite command is input to a sector of one semiconductor storage medium of a pair of semiconductor storage media capable of erasing data in units of blocks constituted by a plurality of sectors. The data of the sector to be rewritten is rewritten in the buffer memory while the data of the block including the sector to be rewritten of the one semiconductor storage medium is temporarily transferred to the buffer memory for storing the data. Is transferred to the erased block of the other semiconductor storage medium together with the data of the sector not to be rewritten, and after the transfer of the data to the other semiconductor storage medium is completed, the transferred data in the one semiconductor storage medium is transferred in block units. It is characterized by erasing.

According to the fourth aspect of the present invention, when a rewrite command for a sector of one of the semiconductor storage media of the pair of semiconductor storage media is input, first, all of the blocks constituting the block including the sector to be rewritten. The process of sequentially transferring the data of the sector to the buffer memory is started. If the data transferred to the buffer memory is data of a sector to be rewritten, the data is rewritten based on the rewrite data specified by the rewrite instruction, and the rewritten data is transferred to the erased block of the other semiconductor storage medium. If the data is not to be rewritten, the data is transferred to the erased block of the other semiconductor storage medium without rewriting.
Thus, the rewritten data can be written to the erased block without waiting for the end of the erase operation of the block in one semiconductor storage medium. At this time, the transfer of data to the buffer memory of the block including the sector to be rewritten is performed in parallel with the transfer of data from the buffer memory to the erased block of the other semiconductor storage medium. As a result, the time required for processing the rewrite instruction can be reduced.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, a rewrite command is input to a sector of one of the pair of semiconductor storage media and an erased block is stored in the other semiconductor storage medium. In the case where no data exists, data is transferred after generating an erased block in the other semiconductor storage medium.

According to a fifth aspect of the present invention, similarly to the second aspect, when there is no erased block in a semiconductor storage medium to which data is to be transferred, each of the pair of semiconductor storage media is Performs the equalization of the number of erased blocks. By performing the equalization, an erased block is generated in the semiconductor storage medium to which data is to be transferred. After equalizing the number of erased blocks, data transfer is started.

Therefore, data can always be written in the erased block without waiting for the end of the erase operation of the block in one semiconductor storage medium, and the data can be transferred to the buffer memory of the block including the sector to be rewritten. Is performed in parallel with the transfer of data from the buffer memory to the erased block of the other semiconductor storage medium, so that the time required for processing a rewrite instruction can be reduced.

According to a sixth aspect of the present invention, in the fourth or fifth aspect, when the idle state for a predetermined time or more is recognized, the number of erased blocks in the pair of semiconductor storage media is reduced. It is characterized in that equalization is performed.

According to a sixth aspect of the present invention, similarly to the third aspect, when it is recognized that the idle state before the rewrite command is input has continued for a predetermined time or more,
The number of blocks of each erased block of the pair of semiconductor storage media is equalized. Thus, the erased block does not exist in the semiconductor storage medium to which the data of the block including the sector to be rewritten should be transferred when the process for the rewritten instruction is performed, so that the process for the rewritten instruction can be performed smoothly. As a result, the processing for the rewrite instruction is not interrupted, so that the time required for the processing can be further reduced.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, the semiconductor disk device 10 according to the first embodiment includes a host interface 12, a microcontroller 14, a buffer memory 16, a storage medium 18, and a block position management unit 20. It is composed of

The microcontroller 14 has a host interface 1 between the host and the semiconductor disk device 10.
2 to control data exchange performed via the control unit 2.

As shown in FIG. 2, the storage medium 18 includes a plurality of pairs (N) of semiconductor memory chips A ₁ and B _1.
Pairs) are provided. These semiconductor memory chips A ₁
ＡA _N , B ₁ ＢB _N are constituted by non-volatile semiconductor memory chips such as flash memories that can retain stored data even when the power is turned off.

Further, a pair of semiconductor memory chips A ₁ -A
_N, B ₁ .about.B _N is different ports 22A, 22
It is connected to the buffer memory 16 via B.

Semiconductor memory chips A _{1 to} A _N , B _{1 to} B
_N has a stored area 26 in which data is stored and an erased area 28 in which no data is stored. Each of the stored area 26 and the erased block 28 includes blocks 26A, 26B,... Composed of a plurality of (eight in this embodiment) sectors 30A to 30H as shown in FIG. , 28A, 28B,
・ ・ Is provided. Note that, in FIG. 3 and FIG. 5 described later, the sectors 30A to 30H in which data is stored are indicated by oblique lines.

Next, a control routine by the microcontroller 14 according to the first embodiment will be described with reference to FIG.

First, in step 100, a rewrite command output from the host is fetched and the buffer memory 16
To memorize. As a result, the command of the rewrite command, the sector number to be rewritten, and the rewrite data are stored in the buffer memory 16. In the next step 102, a rewrite target sector is calculated based on the block position management information of the block position management unit 20. That is,
The sector to be rewritten is the block 2 of the stored area 26.
6A, 26B,...

In the following, as shown in FIGS. 6A and 6B, the sector to be rewritten is the semiconductor memory chip A.
This block 26A is included in _one block 26A.
The case of transferring the data of the sector 30A~30H constituting the A block 28A of the erased area 28 of the semiconductor memory chip B ₁ via the buffer memory 16 will be described as an example.

In step 104, sectors 30A to 30A constituting block 26A including the sector to be rewritten are
The transfer of the H data to the buffer memory 16 is started.
Thereby, the sectors 30A to 30A constituting the block 26A are
The 30H data is sequentially transferred to the buffer memory 16 for each sector.

Subsequently, in step 106, the semiconductor memory chip B ₁ paired with the semiconductor memory chip A _{1 in} which the block 26A including the sector to be rewritten exists.
It is determined whether or not the erased area 28 exists. In step 106, if the erased area 28 is determined to be present in the semiconductor memory chip B ₁ represents,
Move to step 108.

In step 108, it is determined whether or not the transfer of data for one sector has been completed. If it is determined in step 108 that the transfer of data for one sector has been completed, it is determined whether or not the data transferred in step 110 is data of a sector to be rewritten.
If it is determined in step 110 that the data of the sector to be rewritten has been transferred to the buffer memory 16, the process proceeds to step 11 according to the rewrite command from the host.
In step 2, the data in the sector to be rewritten is rewritten, and the process proceeds to step 114. On the other hand, in step 110,
If it is determined that data in a sector other than the sector to be rewritten has been transferred to the buffer memory 16, the process proceeds to step 114 without rewriting the data.

[0040] In the next step 114, transfers the data of a sector that has been transferred to the buffer memory 16 in block 28A of the semiconductor memory chip B ₁ of the erased area 28.

[0041] At step 116, it determines whether all the data of the sector 30A~30H constituting the block 26A including sector to be rewritten which data rewriting is performed is transferred to block 28A of the semiconductor memory chip B ₁ I do. If it is determined in step 116 that there is a sector for which data transfer has not been completed, the transfer of the data of the next sector to the buffer memory 16 is instructed, and the process proceeds to step 108. On the other hand, sectors 30A to 30A constituting block 26A including the sector to be rewritten
If it is determined that all the data of 30H has been transferred to the block 28A, the process proceeds to step 118. When the transfer of the data from the buffer memory 16 to the block 28A is completed, the rewritten data is written in this block 28A and forms a part of the stored area 26 (in FIG. A block formed as a part of the area 26 is indicated by reference numeral 26X).

[0042] Since the transfer of data from the semiconductor memory chip A ₁ block 26A to the buffer memory 16, and the transfer of data from the buffer memory 16 to the semiconductor memory chip B ₁ block 28A is performed for each sector, 1 block of data transfer from the semiconductor memory chip a ₁ to the buffer memory 16, and the buffer memory 16
From one block of data to the semiconductor memory chip B ₁ transfer is performed in parallel (see FIG. 5).

In the next step 118, the block 26 of the semiconductor memory chip A ₁ transferred to the buffer memory 16
A data is erased. As a result, the block 26A is in a state where no data is stored, and is newly formed as a part of the erased area 28 (in FIG. 6B, the block formed as a part of the erased area 28 is denoted by a code. 28X). In step 120, the block position management information by the block position management unit 20 is updated. In other words, the transferred data is stored ends this control routine that has been stored in the block 26X semiconductor memory chip B _1.

[0044] In contrast, the erased area 28 is determined not to exist in the semiconductor memory chip B ₁ which is a semiconductor memory chip A ₁ and pair present block 26A including sector to be written in step 106 In this case, the process proceeds to step 122. Step 122
Steps 126 to 126 are the same as those in Step 10 described above.
Steps 8 to 112 are the same as those described above, and a description thereof will be omitted.

[0045] At step 128, it is determined whether all the data of the sector 30A~30H constituting the block 26A including the rewritten sector of the semiconductor memory chip A ₁ is transferred to the buffer memory 16. If it is determined in step 128 that there is a sector for which data transfer has not been completed, the transfer of the data of the next sector to the buffer memory 16 is instructed, the process proceeds to step 122, and the above-described processing is repeated. Execute. On the other hand, if it is determined that all the data of the sectors 30A to 30H constituting the block 26A including the sector to be rewritten have been transferred, the process proceeds to step 130.

In step 130, the buffer memory 16
Area 26 of semiconductor memory chip A ₁ transferred to
Of the block 26A is erased. Next Step 1
32, the sector 30 stored in the buffer memory 16
Transferring data A~30H in the semiconductor memory chip A ₁ block 26A. That is, after erasing the data in the block 26A, the data is transferred and written to the same block 26A again.

As described above, since the storage medium 18 is provided with a plurality of pairs (N sets) of the semiconductor memory chips A ₁ and B ₁ , one of the paired semiconductor memory chips A ₁ and B ₁ is provided. Transfer of data from the buffer memory 16 to the block in the erased area of the other semiconductor memory chip of the paired semiconductor memory chip without waiting for the end of the data erasing operation in the block of the stored area of FIG. And the data transfer from the block in the stored area of one semiconductor memory chip to the buffer memory is performed in parallel with the data transfer from the buffer memory to the block in the erased area of the other semiconductor memory chip. Can reduce the time required for processing the rewrite instruction output from.
[Second Embodiment] Next, a second embodiment will be described. Since the second embodiment has substantially the same configuration as that of the first embodiment, the same reference numerals are given to the same components in FIGS. 7 to 10, and the detailed description is omitted.

As shown in FIG. 8A, the first embodiment
In one embodiment, for example, one semiconductor memory chip A₁Or
From the other semiconductor memory chip via the buffer memory 16.
B ₁If data is transferred continuously to
Semiconductor memory chip B₁Block of erased area 28
28A, 28B,... Gradually decrease. Finally
Is the other semiconductor memory as shown in FIG.
Chip B₁No erased area 28 exists. There
In the semiconductor disk device according to the second embodiment,
Can be rewritten as described below, as shown in FIG.
Control microcontroller 14A and erased block
And a lock control unit 40.

Next, a control routine by the microcontroller 14A of the second embodiment will be described with reference to FIG. In the control routine of FIG. 9, the same parts as those of the control routine of the first embodiment (see FIG. 4) are denoted by the same reference numerals, and description thereof will be omitted. Further, the second embodiment will be described using the same example as the first embodiment.

In step 102, the rewrite target
After calculating the sector, the next step 106 is to rewrite
Semiconductor having a block 26A including a target sector
Memory chip A₁Semiconductor memory chip paired with
B₁It is determined whether or not the erased area 28 exists.
In this step 106, the semiconductor memory chip B ₁
When it is determined that the erased area 28 does not exist in the
Then, the process proceeds to step 130. In step 130
Is an erased block consisting of a microcomputer, etc.
A signal instructing the execution of the equalization process to the
Power.

Here, the equalization processing will be described with reference to FIG.

When the signal output from the microcontroller 14A is input to the erased block control unit 40,
The routine shown in FIG. 10 is started, and in step 140, the semiconductor memory chip B _{1 in which the} erased area 28 does not exist.
Blocks 26A, 26 in which data is stored from
The data of B and 26C is transferred to the buffer memory 16.
Next, in step 142, the buffer memory 16 to the transferred block 26A, 26B, block 28 of the erased area 28 of the 26C data semiconductor memory chips A ₁
A, 28B and 28C. Then, step 14
At 4, a block 26A of the semiconductor memory chip B ₁ which transfers data to the buffer memory 16, 26B, erases the 26C data, and updates the block position management information of the block position management unit 20. Thus, a new erased area is formed in the semiconductor memory chip B ₁ (see FIG. 8 (C)). The number of blocks to be transferred and erased may be equal to or larger than the number of blocks to be rewritten.

In step 132 of the control routine of FIG. 9, it is determined whether or not the equalization processing has been completed. this is,
Consideration is given to temporarily suspending the processing for the rewrite command during the execution of the equalization processing in the erased block control unit 40. If it is determined in step 132 that the equalization processing has been completed, step 104
Then, the same processing as in the first embodiment is executed.

[0054] When the erased area 28 in the semiconductor memory chip B ₁ should transfer data is not present in this way, the erased area 2 by performing the equalization process
8 is generated, the erase operation of the other semiconductor memory chip from the buffer memory is always performed without waiting for the end of the data erase operation in the block of the stored area of one semiconductor memory chip of the pair of semiconductor memory chips. Transfer of data to the block of the area can be started, and data transfer from the block of the stored area of one semiconductor memory chip to the buffer memory is performed from the buffer memory to the block of the erased area of the other semiconductor memory chip. Is performed in parallel with the data transfer, so that the time required for processing the rewrite command output from the host can be reduced.

In the above description, an example is described in which the erased block control unit 40 is provided separately from the microcontroller 14A.
May be executed by the microcontroller 14A. [Third Embodiment] Next, a third embodiment will be described. The third embodiment is different from the first embodiment and the second embodiment.
Since the configuration is substantially the same as that of the embodiment, the same components are denoted by the same reference numerals, and detailed description is omitted.

In the above-described second embodiment, when the erased area does not exist in the semiconductor memory chip paired with the semiconductor memory chip in which the block including the sector to be rewritten exists, the erased block control unit The process of equalizing the number of blocks in the erased area is being executed. However, since the equalization processing is performed after the rewrite instruction is input, it is necessary to temporarily suspend the processing for the rewrite instruction during the execution of the equalization processing. Therefore, the third
In the semiconductor disk device according to the embodiment, as shown in FIG. 11, a microcontroller 14B for executing a rewriting process described below is provided, and an erased block control unit 40 composed of a microcomputer or the like is provided with a timer. 42, and the process of equalizing the number of blocks in the erased area 28 is executed when a predetermined idle state or more is recognized.

A control routine of the microcontroller 14B according to the third embodiment will be described with reference to FIG.
The same parts as those in the control routine in FIGS. 4 and 9 are denoted by the same reference numerals, and description thereof will be omitted.

First, in step 150, it is determined whether a rewrite command has been input. If it is determined in step 150 that the rewrite command has not been input, that is, if the semiconductor disk device is in the idle state, the process proceeds to step 152. Step 152
Then, an idle signal is output to the erased block control unit 40. This activates the routine shown in FIG. Here, the operation of the erased block control unit 40 after outputting the idle signal will be described with reference to FIG.

First, at step 160, the idle signal
After the output of, whether a predetermined time has elapsed by the timer 42 or the like
Determine whether or not. As a result, the semiconductor disk device
The duration of the idle state can be determined.
If the predetermined time has elapsed in step 160,
If it is determined, the process proceeds to step 162 and the semiconductor
Memory chip A₁Number of blocks in the erased area 28 of
Semiconductor memory chip B ₁Block of erased area 28
Performs a number equalization process. For equalization processing,
Since the second embodiment is the same as the second embodiment (see FIG. 10), its explanation will be omitted.
Omitted.

In step 154 of the control routine shown in FIG. 12, it is determined whether or not the equalization processing has been completed. If it is determined in step 154 that the equalization processing has been completed, the processing shifts to step 100 and performs the same processing as described above. That is, in the semiconductor disk device according to the third embodiment, equalization processing is executed before a rewrite command is input.

Thus, the processing can be smoothly performed without temporarily interrupting the processing for the rewrite command from the host. Therefore, the time required for processing the rewrite instruction can be further reduced.

In the third embodiment, the timer 4 for recognizing the continuation of the idle state of the semiconductor disk device is set.
2 has been described in which the operation of the erased block control unit 40 is directly controlled. However, a timer is provided in the microcontroller to determine whether or not a predetermined time has elapsed in the idle state. 4
A signal for causing the equalization processing to be zero may be output. Further, the determination whether the idle state has passed for a predetermined time and the equalization processing may be executed by the microcontroller.

In this embodiment, the case where the equalization processing is executed so that the number of blocks in the erased area in each of the pair of semiconductor memories becomes the same has been described as an example. It is not limited to the same.

Further, the case where the block of the stored area and the erased area of the semiconductor memory chip is composed of eight sectors has been described as an example, but the numerical value is not limited to this.

[0065]

As described above, according to the first and fourth aspects of the present invention, since a pair of semiconductor storage media are provided, the buffer can be provided without waiting for the end of the data erasing operation in one of the semiconductor storage media. The transfer of data from the memory to the erased block of the other semiconductor storage medium can be started, and the data transfer from one semiconductor storage medium to the erased block of the other semiconductor storage medium can be started. Since the data transfer is performed in parallel with the data transfer, the time required for processing the rewrite command output from the host can be shortened.

According to the second and fifth aspects of the present invention, the equalization processing for generating the erased blocks in the pair of semiconductor storage media is performed, so that even if the erased blocks do not exist, the data can be deleted. It has an excellent effect that transfer can be performed.

Further, according to the third and sixth aspects of the present invention, when the idle state for a predetermined time or more is recognized, the equalization processing for generating the erased block is performed, so that the processing for the rewrite instruction is smoothly performed. It has an excellent effect that it can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of a semiconductor disk device according to a first embodiment.

FIG. 2 is a schematic configuration diagram showing an internal configuration of a storage medium.

FIG. 3 is a configuration diagram illustrating details of a semiconductor memory chip provided in a storage medium.

FIG. 4 is a flowchart showing a control routine of the semiconductor disk device according to the first embodiment.

FIG. 5 is an explanatory diagram showing a process for a rewrite instruction.

6A is a schematic configuration diagram illustrating a semiconductor memory before a rewrite command is output, and FIG. 6B is a schematic configuration diagram illustrating the semiconductor memory after a process for the rewrite command is completed.

FIG. 7 is a schematic block diagram of a semiconductor disk device according to a second embodiment.

FIG. 8A shows a semiconductor memory before a rewrite command is output, and FIG. 8B shows a semiconductor memory in which data transfer from one semiconductor memory chip to another semiconductor memory chip is continuously performed; (C) is a schematic configuration diagram showing the semiconductor memory after the equalization process is performed by the erased block control unit.

FIG. 9 is a flowchart showing a control routine of the semiconductor disk device according to the second embodiment.

FIG. 10 is a flowchart illustrating an equalization processing routine in an erased block control unit.

FIG. 11 is a schematic block diagram of a semiconductor disk device according to a third embodiment.

FIG. 12 is a flowchart showing a control routine of the semiconductor disk device according to the third embodiment.

FIG. 13 is a flowchart illustrating an operation routine of an erased block control unit.

FIG. 14 is a schematic block diagram of a conventional semiconductor disk device.

FIG. 15 is an explanatory diagram showing processing for a rewrite command in a conventional semiconductor disk device.

[Explanation of symbols]

18 storage medium (semiconductor storage media) 20 block position managing section 26 the stored area 28 erased area (erased block) 40 erased block controller (erased block control means) 42 Timer A ₁ ~A _N, B ₁ ~ _BN semiconductor memory chip

Claims (6)

[Claims] 1. A pair of semiconductor storage media capable of erasing data in units of blocks each composed of a plurality of sectors, and block position management information indicating a block position of data stored in the semiconductor storage medium. A block position management unit, a buffer memory for temporarily storing data, and, when a rewrite instruction for a sector of one of the semiconductor storage media is input, a rewrite target based on the block position management information of the block position management unit. Determining a block position including a sector, transferring the data of the block including the sector to be rewritten of the one semiconductor storage medium to the buffer memory, rewriting data of the sector to be rewritten based on a rewrite command, Transfer of data to the erased block of the other semiconductor storage medium, and A control unit that controls erasure of data in block units in the one semiconductor storage medium. 2. The semiconductor memory device according to claim 1, further comprising an erased block control means for equalizing the number of said erased blocks in said pair of semiconductor storage media. 3. The semiconductor memory device according to claim 2, wherein the number of erased blocks is equalized when an idle state for a predetermined time or more is recognized. 4. When a rewrite command is input to a sector of one semiconductor storage medium of a pair of semiconductor storage media capable of erasing data in units of blocks constituted by a plurality of sectors, the one semiconductor storage medium While temporarily transferring the data of the block including the sector to be rewritten on the medium to the buffer memory for storing data, the buffer memory rewrites the data of the sector to be rewritten, and replaces the rewritten data of the sector not to be rewritten. Transferring the data together with the data to an erased block of the other semiconductor storage medium, and after transferring the data to the other semiconductor storage medium, erasing the transferred data in the one semiconductor storage medium in block units. Control method of a semiconductor memory device to be rewritten. 5. A rewrite command for a sector of one of the semiconductor storage media of the pair of semiconductor storage media is input,
5. The rewrite control of a semiconductor memory device according to claim 4, wherein, when the erased block does not exist in the other semiconductor storage medium, the data is transferred after generating the erased block in the other semiconductor storage medium. Method. 6. The system according to claim 4, wherein when an idle state for a predetermined time or longer is recognized, the number of erased blocks in the pair of semiconductor storage media is equalized. Rewriting control method for a semiconductor memory device.