Error detection/correction and fault detection/recovery – Pulse or data error handling – Memory testing
Reexamination Certificate
1999-05-26
2002-06-11
Decady, Albert (Department: 2133)
Error detection/correction and fault detection/recovery
Pulse or data error handling
Memory testing
C714S710000
Reexamination Certificate
active
06405332
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a storage device and an alternate processing method for defective sectors of the storage device, and more particularly, the present invention relates to a non-volatile semiconductor memory with block unit erase only for performing erasure of data at the block unit level, and an alternate processing method for defective sectors of the non-volatile semiconductor memory.
This application is a counterpart of Japanese application Serial Number 145714/1998, filed May 27, 1998, the subject matter of which is incorporated herein by reference.
2. Description of the Related Art
In general, an external memory serves as an auxiliary memory for information processing equipment. The external memory has a buffer memory and a cache controller which temporarily stores data supplied from the information processing equipment, for example a host computer, for improving access speed, or which temporarily stores data during the reading of data from a memory that is being transferred to the host computer. The external memory is made up of a disk memory and a controller which controls the disk memory, and is integrated as a peripheral apparatus that is provided a peripheral controlling function by using an internal bus. Recently, a non-volatile semiconductor memory is being used for the memory. The non-volatile semiconductor memory is for example an EPROM (erasable programmable ROM) or an EEPROM (electrically erasable programmable ROM).
Further, the external memory recognizes that a sector is defective when a normal write and read to the sector can not be performed, and it writes the result to a defective sector map. For example, a magnetic disk with a capacity of 2 Gbytes may have a memory including a write area with 2000 error sectors in the defective sector map. This is a conventional alternate processing method for defective sectors. Detection of a defect is performed when the disk memory is formed or low level formatting is performed. A LBA (logical block address) is assigned for normal sectors when logical formatting is performed. Defective sectors occur when the disk memory is operated. At this time, the LBA is assigned by the logical formatting, and as a result the defective sectors are written to the defective sector map. Further, an alternate sector is provided.
It is desirable to use the sectors effectively by decreasing the number of data writing operations for an alternate processing.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a storage device that can use the sectors effectively by decreasing the number of data writing operations for alternate processing.
According to one aspect of the present invention, for achieving the above object, there is provided a storage device comprising: a memory which has a user sector area, an alternate information area, and a spare sector area, the user sector area stores user data, the alternate information area stores information identifying a defective sector and an alternate sector which is alternated for the defective sector, and the spare sector area stores user data written to the defective sector; an alternate processing controller which reserves a sector of the spare sector area instead of the defective sector when the defective sector is present in the user sector area and which controls the writing of user data to all normal sectors of the user sector area; and a data storing unit which temporarily stores, when performing alternate processing, the data which is written to the defective sector; wherein the alternate processing controller stores data to the data storing unit when performing an alternate processing on data which is written to the defective sector, and transfers at one time a plurality of sector data from the data storing unit to the spare sector area.
According to another aspect of the present invention, for achieving the above object, there is provided a storage device comprising: a memory which has a user sector area, an alternate information area, and a spare sector area, the user sector area stores user data, the alternate information area stores information identifying a defective sector and an alternate sector which is alternated for the defective sector, and the spare sector area stores user data written to the defective sector; an alternate processing controller which reserves a sector of the spare sector area instead of the defective sector when the defective sector is present in the user sector area and which controls the writing of user data to all normal sectors of the user sector area; and the memory also has a temporary area for temporarily storing a block including a defective sector; wherein the alternate processing controller temporarily stores the block including the defective sector to the temporary area and stores at one time data for a plurality of defective sectors to the spare sector area.
An object of the present invention is to provide an alternate processing method for defective sectors of a storage device that can use the sectors effectively by decreasing the number of data writing operations for alternate processing.
According to one aspect of the present invention, for achieving the above object, there is provided an alternate processing method for defective sectors of a storage device comprising: providing a memory which has a user sector area, an alternate information area, and a spare sector area, the user sector area stores user data, the alternate information area stores information identifying a defective sector and an alternate sector which is alternated for the defective sector, and the spare sector area stores [an alternate] user data written to the defective sector; providing an alternate processing controller which reserves a sector of the spare sector area instead of the defective sector when the defective sector is present in the user sector area and which controls the writing of user data to all normal [all] sectors of the user sector area; temporarily storing data to a data storing unit when performing alternate processing on data which is written to the defective sector; and storing at one time a plurality of sector data from the alternate processing to the spare sector area by reading from the data storing unit.
According to another aspect of the present invention, for achieving the above object, there is provided an alternate processing method for defective sectors of a storage device comprising: providing a memory which has a user sector area, an alternate information area, and a spare sector area, the user sector area stores user data, the alternate information area stores information identifying a defective sector and an alternate sector which is alternated for the defective sector, and the spare sector stores user data written to the defective sector; providing an alternate processing controller which reserves a sector of the spare sector area instead of the defective sector when the defective sector is present in the user sector area and which controls the writing of data to all normal sectors of the user sector area; providing the memory with a temporary area for temporarily storing a block including a defective sector; temporarily storing in the temporary area the block including the defective sector; and storing at one time the data of the plurality of the defective sectors stored in the temporary area to the spare sector area.
REFERENCES:
patent: 4814903 (1989-03-01), Kulakowski et al.
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patent: 5357381 (1994-10-01), Yasuda et al.
patent: 5818654 (1998-10-01), Reddy et al.
patent: 5848438 (1998-12-01), Nemazie et al.
patent: 6021101 (2000-02-01), Satoh
Bando Kazuhiko
Hiratsuka Shinji
De'cady Albert
Oki Electric Industry Co, Ltd.
Rabin & Berdo P.C.
Torres Joseph D.
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