JPH06119252A - Information processor - Google Patents

Abstract

PURPOSE:To use a storage device in which the number of times of rewriting is limited also for storing data rewritten frequently by uniformizing the number of times of rewriting of a block in the storage device concerned which can be erased and written electrically by all ships or a block unit, and prolonging virtual service life of the storage device. CONSTITUTION:An area is constituted by setting one or plural blocks being an erasure unit of an electrically writable nonvolatile storage device as one unit. Erasure and write of data are executed for every area, one of the areas of the storage device is set as a management information area to store management information of storage data in the storage device, in all the areas, a storage part for showing whether it is the management information area or not is provided, and in the management information, a storage part in which the number of times of writing of all the areas is stored is provided. In such a way, the storage device in which the number of times of rewriting is limited can be used for storing data rewritten frequency, as well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a word processor,
The present invention relates to a management device for a semiconductor nonvolatile memory device incorporated in an information processing device such as a personal computer.

[0002]

2. Description of the Related Art A memory device (hereinafter referred to as a flash memory) that is electrically erasable and writable in all chips or blocks is non-volatile, so that a power source for holding stored data is unnecessary, and a program Suitable for storing data and data. However, since the number of times of erasing or writing is limited, it cannot be used for the purpose of rewriting frequently.

Conventionally, as a large-capacity, non-volatile storage device, a fixed disk device, which has no prescribed number of rewrites, has been used.

[0004]

The flash memory is
Although it has advantages such as low power consumption, light weight, and excellent impact resistance as compared with the fixed disk, there is a problem that the number of rewriting is limited.

In a normal information processing apparatus, various data such as operation programs, character font data, and various document file data temporarily stored are mixedly stored in a non-volatile storage device. Generally, operating programs and character fonts are rarely rewritten once written. Also, document file data and the like are often rewritten. From this, it is possible to increase the number of times of rewriting of a block having a large number of times of rewriting by making the bias of the number of times of rewriting of each block in the same nonvolatile memory device uniform.

An object of the present invention is to store data for frequent rewriting in a flash memory having a limited number of rewritings by making the number of rewritings of blocks in the flash memory uniform and extending the apparent life of the flash memory. It can also be used.

[0007]

An area is formed by using one or a plurality of blocks, which are erase units of the flash memory, as one unit, and data is erased and written for each area. One of the areas is used as a management information area, and management information of stored data in the flash memory is stored.
In addition, a storage unit (hereinafter referred to as a CD) indicating whether or not the area is a management information area is provided in all the above areas. The management information includes, in addition to information on the usage status and stored data of all areas, a storage unit (hereinafter referred to as WC) that stores the number of times of writing in all areas, a serial number storage unit of the management information area (hereinafter CDSN).

[0008]

Operation: Confirm that nothing is written in the flash memory, and then write various data in each area of the flash memory at the same time as 01H (0 and 1
(A value different from the value at the time of erasing data that includes both) is set.

Next, the management information including the usage status of all areas, information of stored data, etc. and WC of all areas is written. At this time, at the same time, the management information area CD has 10H
(A value different from the value at the time of erasing data and including both 0 and 1 and a value different from the CD in the data area) is written, and 0 is written to CDSN.

With the above, initialization of the flash memory is completed.

At the same time as erasing the contents of the area, the CD in the area is cleared and the initial value is set. For this reason,
The erased area can be distinguished from the data area and the management information area.

In the current semiconductor device technology, the guaranteed number of rewrites for flash memory is 10,000 to 1,000,000.
It is about a time. An appropriate number, such as one to several hundredths, of the guaranteed number of rewrites will be used as the number of area replacements (hereinafter AC
C)). When a write occurs in the flash memory, the management information is used to select the area having the smallest number of rewrites from the areas in which valid data is not stored. Also, the WC of the rewritten area in the management information and the WC of the management information area are incremented to rewrite the management information. At the time of rewriting the management information, if the WC of the management information reaches n times the ACC (n is a positive integer), the area for storing the management information is changed to
Replace with the area with the least number of rewrites in all available areas.

Since the management information area is rewritten every time writing to all areas occurs, the number of times of rewriting increases, but as described above, the management information area is moved every time a certain number of times of rewriting is performed. However, the number of rewrites does not increase only in a fixed area.

This makes it possible to make the number of times of rewriting of blocks in the flash memory uniform and extend the apparent life of the flash memory.

If the deletion of the management information area fails, the value of CDSN is updated and a new management information area is set. Here, there is a possibility that a plurality of CD 10H areas will be created, but if the latest CDSN value is selected as the management information area, it is correct even if the management information area cannot be written and erased. You can select management information.

[0016]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an embodiment of an information processing apparatus according to the present invention.

The CPU 101 is a central processing unit,
It operates according to programs existing in the RAM 102 and the ROM 103, displays on the display device 105, and performs I / O.
The device 106 inputs and outputs data.

The RAM 102 is a randomly readable and writable storage device, and is a CPU 10
Temporarily stores the operating program and data of 1.

The RAM 102 is volatile, and all contents are erased when the power is turned off.

The ROM 103 is a random-accessible read-only storage device, and stores programs for operating the CPU 101 and various data. ROM1
Since 03 is non-volatile, a program that the CPU 101 first executes when the power is turned on is stored.

The display device 105 displays according to a command from the CPU 101.

The I / O device 106 is an input / output device such as a keyboard and a printer, and controls input / output of the information processing device.

The flash memory 104 is a memory device that can be electrically erased and written in all chips or blocks as described above, and stores an operation program, character font data, various temporarily stored document file data, and the like. Various data are stored. In this embodiment, a flash memory is used, which is accessed continuously for each block.

Next, the flash memory 10 according to the present invention.
The control method of No. 4 will be described.

FIG. 2 is an embodiment showing the structure of data stored in the flash memory 104. The flash memory 104 has a data area, a management information area, and an unused area. CD = 01 at the beginning of the data area
H, CD = 10H is written at the beginning of the management information area. Further, in the management information area, the CDSN is written, and information indicating what number management information is stored. The unused area is an area where data is erased but not written, and all bits are 1
Or it is 0.

Next, a method of accessing the flash memory 104 will be described in detail.

FIG. 3 is a flow when writing data for the first time. At 301 and 302, the data area is written, and at 303 and 304, the management information of the written data is written. An area where nothing is written (unused area) has all bits set to 1 or 0, and is distinguished by the value of CD.

FIG. 4 shows the processing when the power is turned on in normal use. Since the management information of the flash memory 104 is frequently used, it is a process to be loaded in the RAM 102 when the power is turned on. When selecting the management information area,
First, in 401, an area of CD = 10H is searched for in all areas. In 402 and 403, if there is a failure in deleting the management information area before, there are a plurality of areas with CD = 10H, so the management information area with the largest CDSN value is selected and loaded into the RAM 102. By this processing, the correct management information written before the power is turned on can be known, and by loading it on the RAM 102, the CPU 101 can quickly use the management information.

FIG. 5 shows a process of reading data from the flash memory 104. In 501, an area where necessary data exists is searched from the management information, and 502
Read on. The reading of data from the flash memory 104 is performed serially, and the CPU 101 uses the RAM 10
Expand to 2. At this time, the CD value can be skipped so that data that spans a plurality of areas can be continuously expanded on the RAM 102. There is no limit to the number of times data can be read from the flash memory.

FIG. 6 shows a process when rewriting the data in the flash memory 104. When writing to the flash memory 104 such as registration of document file data occurs, an area having the smallest WC is selected from management information on the RAM 102 in 601 and a data area is indicated in 602. CD =
Data is written including 01H. In 603, R
The management information of the data area written in the AM 102 is updated, and the management information is written in 604.

Although the data and management information are written in the flow as described above, there are cases where the internal data must be erased from the used area during the writing process.

Next, referring to FIG. 7, FIG. 8 and FIG.
2, 304, 602, and 604, the data and management information write processing will be described in detail.

FIG. 7 shows a data area writing process.

Reference numerals 701 to 705 show the erasing process when the area to be written is already used.
If the data is erased and it fails, the erase process is performed again. If the data cannot be erased after the predetermined number of times (Z + 1), the process shifts to the alarm processing 1 of 710, the area is regarded as unusable in 711, another area is searched for, and data rewriting processing is performed again.

The alarm processing 1 of 710 corresponds to the display device 10.
5 informs the operator that one area has become unusable. At this time, the usable capacity of the flash memory 104, the number of areas that cannot be used, the percentage of areas that cannot be used, and the like may be indicated. The alarm processing 701 may be omitted if it is not necessary.

Reference numerals 706 to 709 represent data write processing. After writing, check if the written data is normal, and if it is not normal, write again. If the writing cannot be performed after the specified number of Z times, the process proceeds to the alarm processing 1 of 710, and the area is regarded as unusable in 711, another area is searched for, and the data rewriting processing is performed again.

FIG. 8 shows the writing process of the management information area. The processing of 701 to 711 is the same as the writing processing of the data area, but the processing of 801 and 802 is added. In 801 and 802, when the value of WC reaches n times the number of area exchanges ACC (n is a positive integer), the management information area is changed to another area with a smaller WC. A process for changing the management information storage area is shown in FIG. 9 as (A).

In FIG. 9, it is confirmed at 901 whether the WC of the management information has reached the guaranteed number of rewrites of the flash memory used. When the guaranteed number of rewrites has been reached, the alarm processing 2 notifies the operator that the display device 105 has reached the guaranteed number of rewrites. At this time, as in the alarm process 1, the flash memory 104
The available capacity, the number of areas that cannot be used, the percentage of areas that cannot be used, and the number of areas that have exceeded the guaranteed number of rewrites may be indicated. The alarm processing 702 may be omitted if not necessary.

When the area of the management information is changed, first, at 903, the area having the smallest WC is selected from the management information, and the data stored in the area selected at 904 is changed up to that point. The management information area is changed to the area in which the management information is stored and the area having the smallest WC selected in 905 is set as the management information area. When the area change is completed, the data area writing process shown in FIG. 7 or the management information writing process shown in FIG. 8 is performed following (B).

As described above, according to the present invention, the management information area is rewritten each time writing to the data area or the management information area occurs. The number of rewrites in the area can be made uniform.

When data is written as described above, the management information of the flash memory is always rewritten to the latest one, so that the management information is stored in the flash memory even if the power is carelessly turned off. The management information does not disappear.

Further, since the number of times of rewriting blocks in the flash memory can be made uniform as described above, when one area becomes unrewritable or the guaranteed number of times of rewriting is reached, the flash memory is used in all areas. The probability of being disabled is increasing. At this time, alarm processing can be performed to notify the operator that the flash memory is about to be replaced, and good operability can be provided.

[0043]

As described above, according to the present invention, by making the number of times of rewriting of blocks in the flash memory uniform and extending the apparent life of the flash memory,
The flash memory, which has a limited number of rewrites, can be used for storing data that is frequently rewritten.

Further, since the management information of the data in the flash memory is stored in the flash memory, it is not necessary to have another non-volatile storage device for storing the management information.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of an information processing apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of data stored in a flash memory.

FIG. 3 is an operation flow when writing data to a flash memory for the first time.

FIG. 4 is a flow chart of management information reading processing when the power is turned on.

FIG. 5 is a data reading process flow.

FIG. 6 is a processing flow when rewriting data.

FIG. 7 is a flow chart of a writing process to a data area.

FIG. 8 is a flow chart of a writing process to a management information area.

FIG. 9 is a processing flow for changing the area of management information.

[Explanation of symbols]

101 ... Central processing unit, 102 ... RAM, 103 ... Flash memory, 104 ... Display device, 105 ... I / O device.

Claims (5)

[Claims] 1. An electrically erasable and writable memory device for all chips or block units, wherein an area is formed by using one or a plurality of blocks, which are the erase units of the memory device, as one unit. In an information processing device for erasing and writing data for each area, one of the areas of the storage device is a management information area,
The management information of the storage data in the electrically writable non-volatile storage device is stored in the area, and a storage unit for indicating whether or not the area is the management information area is provided in all the areas, and the management information is also provided. An information processing device, wherein a storage unit storing the number of writings in all areas is provided in the information processing device. 2. The information processing apparatus according to claim 1, wherein the management information area is changed to an area with the smallest number of writings in all areas every time the number of writings in the area for storing management information exceeds a certain number. An information processing device characterized by: 3. The information processing apparatus according to claim 1, wherein the management information is provided with a serial number, and when the management information cannot be erased, the latest management information is distinguished by the serial number. apparatus. 4. The information processing apparatus according to claim 1, wherein a warning is issued when erasing or writing of data in the electrically writable nonvolatile memory device fails. 5. The information processing apparatus according to claim 1, wherein a warning is issued when the number of times data is rewritten in the electrically writable nonvolatile storage device exceeds the guaranteed number of times of rewriting. apparatus.