JPH10188584A - Memory control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a memory control device limitlessly rewritable, by setting an area for storing a use state to EEPROMS of being used and spare systems permitting a finite count of rewritings, switching to the spare system when the use state is against regulations, and displaying the fact. SOLUTION: A flag/pointer area for writing an address of a block being used and a count filed for storing a count of reloadings are set on an EEPROM 1 of a system used at present. Only one block is used at al times, and a next block is used when the count of reloadings to the block reaches a regulated value. When all blocks of the EEPROM 1 of the current system are used up, a swithcing control circuit 3 sets a fresh block to an EEPROM 2 of a spare system and switches a spare system used heretofore to be a fresh current system after data of a final block of the current system are transferred. A computer 7 controls the total operation by a memory control means 6 of software and informs a user of use states of the EEPROMs 1, 2 through a display 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a storage controller, and more particularly, to a storage controller using an EEPROM.

[0002]

2. Description of the Related Art When a power supply of an electronic device equipped with a computer circuit including a CPU, a memory and embedded software and a man-machine interface (MMI) is turned on, the same state as when the power supply of the device was turned off last time is obtained. In order to start up, it is necessary to keep storing state data even when the state of the apparatus is turned off. On the other hand, when the power is connected (during use of the apparatus), it is necessary to rewrite the memory to the latest state (data) every time the state of the apparatus is changed.

Conventionally, for such purpose, for example, EEPR
OM (Electrically Erasable Programmable Read-Only
Memory: Use of non-volatile (memory is not lost even when the power is turned off) semiconductor memory such as electrically erasable and electrically writable read-only memory, or normal (volatile) semiconductor memory using a battery Things like backing up have been done.

However, the non-volatile memory is EEPRO.
Not only semiconductor memories such as M, but also magneto-optical disk memories, for example, have a limited number of rewrites (although the number of limited rewrites varies greatly depending on the type of memory), and battery backup is limited by battery life. At the same time, if the power supply of the device is cut off for a long time, the device is discharged and the memory of the memory is lost.

Japanese Patent Application Laid-Open No. 2-242473 proposes a method of managing the number of rewrites in a magneto-optical memory. The limit value of the number of times of rewriting of a magneto-optical memory is generally quite large (for example, one million times).
It is considered unnecessary in practical use.

[0006] Therefore, it is sufficient to manage only blocks that are accessed very frequently, such as gate blocks. Only for such a block, means for storing the number of times of writing in block units is provided. When the number of times of writing reaches a certain value, a pointer to a substitute block is recorded in that block, and thereafter the original block is written. It is conceivable to access a substitute block instead when the access is made.However, since the gate block is updated frequently, the substitute block is further assigned to the substitute block, and the access time increases. Easy to get results.

[0007] When a file is created on a removable medium and an update process is performed, the gate block is removed by an operation error or the like during the process, and the gate block is used in another system without being noticed. In order to prevent file destruction by using the medium, it is effective to provide a gate that locks before the file update process and unlocks after the update process.A block including such a gate is referred to as a gate block. Call.

In order to solve such a problem, a gate block including a count field for storing the number of times of writing and a label block including a gate block pointer field pointing to the gate block are provided on a storage medium that allows a finite number of rewrites. The count field is updated when the gate block is rewritten.When the count field value reaches a certain value, a new recording area is secured as a gate block area, and the count field is initialized. Is recorded in a newly secured area, and the gate block pointer field in the label block is updated to point to the new gate block.

[0009]

The problem to be solved by the present invention is disclosed in Japanese Patent Laid-Open No. 2-242.
The proposal described in Japanese Patent No. 473 is effective when the recording medium is removable from the gate block (assuming that the removed medium is inserted into another device). Is assumed to be sufficiently large. Even if the limit value of the number of times of rewriting of the medium is large, it is still finite, and the method proposed in Japanese Patent Application Laid-Open No. 2-242473 is not suitable for a device that requires high reliability and high durability. Insufficient.

[0010] It is an object of the present invention to provide a storage control device that can be rewritten indefinitely.

[0011]

SUMMARY OF THE INVENTION A storage control device according to the present invention has a pair of finite number of rewrite limits of a working system and a spare system for storing computer status data, each of which has a plurality of blocks. Storage means, means for sequentially recording the status data and the number of rewrites of the block by sequentially using the blocks of the active nonvolatile storage means, and the number of rewrites of the block has reached the number of rewrites Means for switching the blocks to be used sequentially, and, when the number of rewrites of all the blocks of the non-volatile storage means of the active system reaches the rewrite limit value, the active system and the standby system of the non-volatile storage means Current / standby switching control means for controlling switching.

The operation of the present invention is as follows. A storage control device according to the present invention includes a flag / pointer area indicating whether or not the memory is currently used, a count field storing the number of times of rewriting, on a storage medium having a working / standby configuration and permitting a finite number of rewrites. The data area of the storage medium is divided into several blocks including a data field for storing the status data, and only one block is always used, and a pointer area indicating the address of the block and the number of rewrites of the count field are defined. When the value is exceeded, the blocks in the data area are changed, and when all the data areas in the storage medium are used up, a new block is set in the spare storage medium, and the latest block in the active system is set. After the data transfer, the previous standby system is switched to the new active system, and the previous active system is Tana switched to the standby system, and displays the switching of the active replacement system, by enabling exchange side of the storage medium became newly standby system, to allow unlimited rewriting the entire apparatus.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of a storage control device according to the present invention. Referring to FIG. 1, the storage control device according to the present invention performs a finite number of times (for example, 100,000 times).
Working / standby EEP, a storage medium that allows overwriting of data
The ROM 1, 2, the switching control circuit 3 for switching between the active and the standby systems of the EEPROMs 1, 2, the computer circuit 7 for controlling the entire device, the data reading and writing to the EEPROMs 1, 2, and the instruction to the switching control circuit 3 A memory management means 6, which is software of a computer circuit 7 for notifying the operator through the display circuit 4 and the display 5, a display circuit 4 for displaying the usage status of the EEPROMs 1 and 2 to the operator, and a display 5.

FIG. 2 shows an example of use of the data areas of the memories of the EEPROMs 1 and 2. The status data of the device is data (field) (word unit) 11-1 to 11-500.
Is written and read (rewritten), and the number of times of rewriting is determined by counters (fields) 10-1 to 10-500.
Is stored in Data (field) 11-1 to 11-
500 and counter (field) 10-1 to 10-50
0 is set and 1 data / counter block 12-
1 to 12-4.

In one EEPROM 1 or 2, for example, 4 (data / counter) blocks 12-1 to 12-
4 has a capacity to secure any one of the blocks 12-1 to 12-1.
Pointer area 9 indicating whether 2-4 is being used. Currently, this EEPROM 1 or 2 is actually used (currently used).
A flag / pointer area 13 is formed by a flag area 8 indicating whether the flag has been set.

The operation of the embodiment of the present invention is as follows. As shown in FIG. 3, which is a flowchart of the memory management means 6, the computer circuit 7 stores the status data in the active EEPROM 1.
Alternatively, the data is written into the data fields 11-1 to 11-500 of the blocks 12-1 to 12-4 (step 21), and the counter field 10 of the working blocks 12-1 to 12-4 of the active EEPROM 1 or 2 is written. −
The count number of 1 to 10-500 is increased by 1 (step 22).

It is determined whether the count exceeds the limit value of the number of times of rewriting of the EEPROMs 1 and 2 (step 23). In the case of YES, it is determined whether or not empty blocks 12-1 to 12-4 remain in the current EEPROM 1 or 2 (step 24). In the case of YES, the currently used block 12 of the pointer area 9 is determined. Pointers indicating -1 to 12-4 are set to the next vacant blocks 12-1 to 12-4.
(Step 25).

Next, the currently used block 12
State data 11-1 to 11- constituting -1 to 12-4
500 and the like are transferred to the next blocks 12-1 to 12-4 (step 26). At the same time, the display circuit 4 controls the display circuit 4 to indicate that the used and used areas have increased in the EEPROM 1 or 2, and ends the processing.

If step 24 is NO, the standby system E
Whether the EPROM 2 or 1 is unused (used) or not is determined by the flag area 8 of the EEPROM 2 or 1 (step 28).
Alternatively, if the replacement of 1 is neglected), the display circuit 4 is controlled to output an alarm to the display 5 and the process is terminated (step 33).

In the case of YES, the flag area 8 of the EEPROM 2 or 1 is rewritten and the first blocks 12-1 to 12-4 are used to indicate that the EEPROM 2 or 1 of the standby system is newly used as the active system. To indicate this, the pointer area 9 is rewritten (step 29).

The original working EEPROM 1 or 2
Of the latest blocks 12-1 to 12-4 of the current EEPROM 2 or 1
Are transferred to the first blocks 12-1 to 12-4 (step 30). By the switching control circuit 3, the EEPROM
Switching between 1 and 2 (working system / standby system) (step 3
1). The display circuit 4 indicates that the original active EEPROM 1 or 2 has become the standby system and has become used (replaceable).
Is output to the display 5 and the process is terminated (step 32).

[0023]

As described above, the storage control device according to the present invention has a flag / pointer area indicating whether or not it is currently used, on a storage medium having a working / standby configuration and permitting a finite number of rewrites. The data area of the storage medium is divided into several blocks including a count field for storing the number of rewrites and a data field for storing the status data of the apparatus, and always uses only one block,
When the pointer area indicating the address of the block and the number of rewrites of the count field exceed a specified value, while changing the block of the data area,
When all data areas of the storage medium are used up,
After setting a new block in the storage medium of the standby system and transferring the data of the latest block of the active system, the old standby system is switched to the new active system, and conversely, the old active system is replaced with the new standby system. The system is switched to the active / standby system, and the switching of the storage medium that has newly become the standby system is made replaceable, thereby providing an effect that the entire apparatus can be rewritten without limitation.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a memory map of an EEPROM according to an embodiment of the present invention.

FIG. 3 is a flowchart of a memory management unit of the EEPROM according to the embodiment of the present invention.

[Explanation of symbols]

 1, 2 EEPROM 3 Switching control circuit 4 Display circuit 5 Display 6 Memory management means 7 Computer circuit

Claims (3)

[Claims] 1. A pair of a working system and a standby system for storing state data of a computer, which has a pair of finite rewrite limit values for finite times,
Nonvolatile storage means each having a plurality of blocks; means for sequentially recording the status data and the number of rewrites of the block by sequentially using the blocks of the active nonvolatile storage means; and rewriting the block. Means for switching the block to be used sequentially when the number of times reaches the number of times of rewriting, and the non-volatile storage means when the number of times of rewriting of all the blocks in the active nonvolatile memory has reached the rewrite limit value. A storage control device, comprising: a current / standby switching control means for controlling the switching between the current system and the standby system. 2. The nonvolatile memory device according to claim 1, wherein said nonvolatile memory means comprises a nonvolatile semiconductor memory device.
The storage control device according to any one of the preceding claims. 3. The non-volatile storage means according to claim 1, wherein when the active / standby switching control means switches between the active system and the standby system of the nonvolatile storage means, the switching is externally displayed. Storage controller.