JPH09319666A - Semiconductor file memory device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the erasure of data even at the time of power supply stop during write by defining a 2nd address corresponding to the 1st address of write request before write as an auxiliary area for write corresponding to the 2nd address writing data into the 1st write requested address. SOLUTION: At the time of formatting a file storage device, an address translation table 9 is prepared and all the 2nd addresses of blocks included in the auxiliary area for reload are set to an auxiliary area table 13 for write. '0' showing the leading position of that auxiliary area table 13 for write is set to an auxiliary area pointer 11 for write and the 2nd address at the position of '0' shown by that auxiliary area pointer 11 for write is updated to the 2nd address corresponding to the 1st write requested address before write. Thus, the erasure of data can be prevented even when trouble such as power supply stop is generated during write.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor file storage device.

[0002]

2. Description of the Related Art A call processing program in a telephone exchange,
A conventional hard disk drive (hereinafter referred to as HDD) is used as a file storage device for storing station data, billing information, and the like.
It was common to use HDDs, but HDDs require replacement and maintenance work due to wear of mechanical parts, etc.
In recent years, electrically operating semiconductor memories are being used as file storage devices.

In a semiconductor memory, which is readable and writable and retains stored contents even when power is turned off, represented by a non-volatile EEPROM or flash memory, a write area must be erased and then written before a write operation. If a failure such as power failure occurs after the previous erasure or during writing, the write data and the existing data stored in the write area will be erased, so that it can be used as a file storage device that requires high reliability. In order to protect data erasure, measures are essential.

As a data protection measure at the time of writing to a file storage device using an EEPROM or a flash memory, there is a system in which a backup power supply is provided in the system to prevent power-off itself during writing.

[0005]

It is necessary to erase the write area before the write operation. In flash memory, the erase area is generally larger than the write unit area. Therefore, when rewriting data, the data in the erase unit area is temporarily stored in the buffer memory, which is a temporary storage area, and the write unit area is Although the erase unit area containing the data is written after erasing, if a failure such as power failure occurs after erasing the data and before or during writing, the data stored in the volatile buffer memory will be lost and the reliability of the device will be lost. Therefore, some measures are required to use a flash memory as a file memory of an exchange that requires high reliability.

In the prior art shown above, the power failure itself is prevented and the data is protected at the time of writing. However, this method requires maintenance and replacement of the backup power source,
Not economically desirable.

An object of the present invention is to realize a highly reliable file storage device using a semiconductor memory with an economical structure and a simple control system.

[0008]

According to the present invention, when writing to a semiconductor memory device, the actual physical position of the semiconductor memory chip corresponding to a first address indicating a virtual position from the CPU with respect to the file storage device. , Instead of directly writing to the second address, write to the second address in the write spare area that does not correspond to the first address, and after writing is complete, write to the first address that requested Makes the second address in which the data is written correspond to the second address, and the second address corresponding to the first address for which the write request has been made before the writing is set as the write spare area.

By the above means, even if a failure such as power failure occurs during writing, existing data is protected and the reliability of the device is improved.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A private telephone exchange (hereinafter referred to as PB) will be described below as an embodiment of a semiconductor file storage device according to the present invention.
As an example of a file storage device used for X), a flash memory is used to configure the file storage device, and a detailed description will be given with reference to the drawings.

FIG. 1 is a block diagram of a PBX using a semiconductor file storage device according to the present invention. The PBX connects terminals that desire communication from among many terminals (telephones, etc.) to enable communication, and the extension circuit 1 connected between the terminals to the subscriber's terminal (extension). And a call line switch 2 installed between a telephone line (generally a public telephone network) and an office line trunk 3 which is an interface with a telephone station (generally a public telephone network). The control device 4 connects the call line switch 2 and the like. It controls the PBX and is equipped with a semiconductor file storage device according to the present invention as will be described later. FIG. 2 is a block diagram of the control device 4 of the PBX shown in FIG. 1, and a central processing control unit (hereinafter CPU) that controls the PBX.
5, a main memory (MM) 6 composed of a volatile memory for storing the operation program and data of the CPU 5, and C
The semiconductor file storage device 7 according to the present invention stores the program and data of the PU 5.

The PBX is generally used continuously for 24 hours, and the file storage device used therein is
Data is rewritten frequently after being energized for 24 hours. For this reason, in the conventional mechanically operated HDD, it is necessary to replace the HDD every certain period due to the limit of the durability of the mechanical portion, so that maintenance-free is desired in operation maintenance. It is suitable to use the semiconductor file storage device including a flash memory, which is a semiconductor memory device that does not operate mechanically as shown. In the flash memory, it is necessary to erase the write area before the write operation. Generally, the erase unit area is wider than the write unit area. It is stored in the buffer memory which is a temporary storage area, and the erase unit area including the write unit area is written after erasing, but it is volatile if a failure such as power failure occurs after erasing data, before writing or during writing. Since the data stored in the memory and the existing data before writing are lost and the reliability of the device is deteriorated, high reliability cannot be realized by simply using the flash memory as the file storage device of the exchange. Therefore, the semiconductor file storage device according to the present invention becomes effective. The semiconductor file storage device according to the present invention will be described below.

FIG. 3 is a block diagram showing an example of the hardware configuration of the semiconductor file storage device of the present invention. In the file storage device of the present invention, the processor 8 for controlling the file storage device and the first address indicating the virtual positioning of the file storage device from the CPU 5 shown in FIG. Address conversion table 9 for converting into a second address which is a specific position, and a rewriting spare area table 13 for storing a second address for each block which is the minimum erase unit of the flash memory in the rewriting spare area, Of the second addresses stored in the rewriting spare area table 13, for rewriting indicating the storage position in the rewriting spare area table 13 of the second address of the block used as the spare area for rewriting first. A spare area pointer 11 and a buffer memory 10 for temporarily storing data to be read from and written to the flash memory Was constructed by flash memory 12 actually stores programs and data. FIG. 4 is a table explanatory view showing a configuration example of the address conversion table 9.
It was created and used as follows. First, the processor formats the file storage (default)
At times, the second address block of the flash memory 12 is sequentially erased, written, and read to check whether the block can be used normally (format check).
A second address indicating a normal block is assigned to the first address. Here, a block whose check result is not normal is not used thereafter. This allocation is repeated, and when the allocation of the second address to the maximum first address is completed, the address conversion table 9 is completed. When the CPU 5 accesses the file storage device with the first address indicating the virtual position, the processor 8 refers to the address conversion table 9 and indicates the second address corresponding to the first address. Access the actual physical location of the flash memory chip.

Next, the operation of the semiconductor file storage device according to the present invention will be described with reference to FIGS. FIG. 5 is a flowchart of the writing process of the semiconductor file storage device, and FIG. 6 is a data transition diagram of the writing process of the semiconductor file storage device.

First, when the file storage device is formatted (initial setting), the address conversion table 9 is created as described above, and all the second addresses of blocks included in the rewriting spare area are written in the spare area table for writing. 1
3 is set, and “0” indicating the start position of the write spare area table 13 is set in the write spare area pointer 11.

Next, the write processing operation will be described with reference to FIGS.

(A) When the CPU 5 issues a write request to the file storage device, the write data is temporarily stored in the buffer memory 10 (FIGS. 5A and 6).
(A)｝.

(B) Erase the block that is the second address at the position indicated by the write spare area pointer 11 in the write spare area table 13 (FIGS. 5B and 6).
(B)}.

(C) The write data in the buffer memory 10 is written in the erased spare area for rewriting {FIG.
(C), FIG. 6 (c)}.

(D) The address conversion table 9 so that the second address corresponding to the first address for which the write request has been made corresponds to the second address at which the data has been written.
To update. The second address at the position indicated by the write spare area pointer 11 in the write spare area table 13 is updated to the second address corresponding to the first address for which the write request was made before the writing. The write spare area pointer 11 is updated to indicate the next table position {FIG. 5 (d), FIG. 6 (d)}.

In the write processing of the semiconductor file storage device according to the present invention, the write data from the CUP 5 is written in the write spare area, and the existing data in the second address corresponding to the first address for which the write request is made until the end of writing is Since it is stored as it is, there is no concern about data loss even if a failure such as power failure occurs during writing to the semiconductor file storage device that uses flash memory that requires erasing before writing, and reliability is greatly improved. ing. That is, the semiconductor file storage device according to the present embodiment is very effective as a PBX file storage device.

[0022]

According to the present invention, at the time of writing to the semiconductor file storage device, the write data is not written to the second address corresponding to the first address but is written to the write spare area, and after the writing is completed. The first address is made to correspond to the second address which was originally the write-use spare area in which writing was performed, and the second address which was originally made to correspond.
Since the address of is used as the spare area for writing, existing data of the writing source is protected even if a failure such as power failure occurs during writing.

[Brief description of drawings]

FIG. 1 is a PB using a semiconductor file storage device of the present invention.
Block diagram of X.

FIG. 2 is a block diagram of a PBX controller according to the present invention.

FIG. 3 is a block diagram showing a configuration of a semiconductor file storage device of the present invention.

FIG. 4 is an explanatory diagram of an address conversion table of the semiconductor file storage device of the present invention.

FIG. 5 is a flowchart of a writing process of the semiconductor file storage device of the present invention.

FIG. 6 is an explanatory diagram of data transition of write processing of the semiconductor file storage device of the present invention.

[Explanation of symbols]

 5 ... Central control device, 6 ... Main memory device, 7 ... Semiconductor file memory device, 8 ... Processor, 9 ... Address conversion table, 10 ... Buffer memory, 11 ... Write spare area pointer, 12 ... Flash memory, 13 ... Write Spare area table.

Claims (3)

[Claims] 1. A semiconductor file storage device comprising a processor, a main storage device, and a storage device configured by using a plurality of electrically rewritable and nonvolatile nonvolatile semiconductor memory elements. A second address for inputting a first address for accessing the file storage device from the processor and indicating a physical position of the semiconductor memory element forming the file storage device corresponding to the first address is provided. Address conversion means for converting to an address, a control processor for controlling the file storage device, and one or more predetermined capacities as spare areas for writing other than the second address area corresponding to the first address When a write request is issued from the processor to the file storage device, the control is provided. The processor writes write data in the write spare area, writes the second address corresponding to the first address for which a write request has been made in the write spare area, and writes the write data in the write spare area. The second address corresponds to the second address corresponding to the first address for which a write request has been made.
The semiconductor file storage device is characterized in that 2. A management table for storing all the second addresses included in the write spare area is provided as a management means for the write spare area of the file storage device, and the management table is stored in the file storage device from the processor. When a write request is issued to the control processor, the control processor
The second address stored in the table is used as a spare area for writing, and after the writing is completed, the second address corresponding to the first address for which a write request is made.
2. The second address of the write spare area where the write data is written in the write spare area is set to the second address corresponding to the first address for which the write request is made. Semiconductor file storage device. 3. A management table managing means for managing the spare write area of the semiconductor file storage device is provided with a pointer indicating a table position used as the spare write area in the management table. The order and the amount of change of the stored second address to be used as a write spare area are variable.
Alternatively, the semiconductor file storage device according to item 2.