EP0548564A2
Expired / Lapsed
EP
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Storage device employing a flash memory
Assignee: Hitachi Ltd
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Filing: 1992-11-24
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Granted: —
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Expires: 2012-11-24
Abstract
Abstract In a semiconductor disk wherein a flash memory into which data is rewritten in block unit is employed as a storage medium; a semiconductor disk comprising a data memory in which file data are stored, a substitutive memory which substitutes for blocks of errors in the data memory, an error memory in which error information of the data memory are stored, and a memory controller which reads data out of, writes data into and erases data from the data memory, the substitutive memory and the error memory. Since the write errors of the flash memory can be remedied, the service life of the semiconductor disk can be prolonged.
Inventors
- 👤 Hajime Yamagami
- 👤 Kouichi Terada
- 👤 Yoshihiro Hayashi
- 👤 Takashi Tsunehiro
- 👤 Kunihiro Katayama
- 👤 Kenichi Kaki
- 👤 Takeshi Furuno
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 13:57
CPC Classifications
G; G11; G11C; G11C29/00; G11C29/70; G11C29/76; G11C29/765; G11C11/00; G11C11/21; G11C11/34; G06; G06F; G06F3/00; G06F3/06; G06F3/0601; G06F3/0602; G06F3/0614; G06F3/0616; G06F3/0628; G06F3/0655; G06F3/0659; G06F3/0668; G06F3/0671; G06F3/0673; G06F3/0679; G11C16/00; G11C16/02; G11C16/06; G11C16/10; G11C16/102; G06F2212/00; G06F2212/20; G06F2212/202; G06F2212/2022; G06F3/0662; G06F3/0664
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
119 words
A storage device employing a flash memory, comprising: a storage area which is divided into physical areas that are identified by physical area identification information; logical area conversion means supplied with logical area identification information being virtual identification information in a data writing operation, for converting said logical area identification information into the physical area identification information corresponding thereto in the case of writing said data into a logical area; and a memory controller which receives said physical area identification information resulting from the conversion, and which writes said data into the physical area; said logical area conversion means being capable of converting the identical logical area identification information into the plurality of items of physical area identification information.
Claim 2
Dependent Claim
126 words
A storage device employing a flash memory as defined in Claim 1, wherein: said physical areas include a data memory area in which data are stored, a substitutive memory area which substitutes for locations of errors in said data memory area, and an error memory area in which addresses of said substitutive memory area corresponding to said locations of said errors in said data memory area are retained as error information; said logical area conversion means converts the location of the error in said data memory area, into the address of said substitutive memory area in accordance with the error information; and said memory controller reads data out of and writes data into said data memory area, said substitutive memory area and said error memory area.
Claim 3
Dependent Claim
44 words
A storage device employing a flash memory as defined in Claim 2, wherein when an error has developed in said substitutive memory area, an address of said substitutive memory area corresponding to said error is retained as error information in said error memory area.
Claim 4
Dependent Claim
30 words
A storage device employing a flash memory as defined in Claim 2, wherein said error memory area retains a situation of use of said substitutive memory area as error information.
Claim 5
Dependent Claim
71 words
A method of reading data by the use of a storage device as defined in Claim 2, comprising the steps of: fetching the error information of said error memory area; and reading the data out of said data memory area when the location of said data in said data memory area is normal in view of said error information, and out of said substitutive memory area when said location is abnormal.
Claim 6
Dependent Claim
115 words
A method of writing data by the use of a storage device as defined in Claim 3, comprising the steps of: fetching the error information of said error memory area; writing the data into said data memory area when the location of said data in said data memory area is normal in view of said error information, and into said substitutive memory area when said location is abnormal; seeking an unused location of said substitutive memory area when an error has developed at the writing step; and writing said data into said unused location, and updating the error information of the error location of either of said data memory area and said substitutive memory area.
Claim 7
Dependent Claim
83 words
A storage device employing a flash memory, comprising: a memory controller which reads data out of and writes data into said flash memory; said flash memory including a data memory area which stores the data therein, a substitutive memory area which substitutes for locations of errors in said data memory area, an error memory area which stores error information of said data memory area therein, and an initialize information area which stores start addresses and storage capacities of the respective memory areas therein.
Claim 8
Dependent Claim
128 words
A storage device employing a flash memory, comprising: a memory controller which reads data out of and writes data into said flash memory; said flash memory being divided into a plurality of storage areas, and including a plurality of data memory areas which store the data therein and which are provided in correspondence with said storage areas, a plurality of substitutive memory areas which substitute for locations of errors in said data memory areas and which are provided in correspondence with said storage areas, a plurality of error memory areas which store error information of said data memory areas therein and which are provided in correspondence with said storage areas, and an initialize information area which stores start addresses and storage capacities of the respective memory areas therein.
Claim 9
Dependent Claim
28 words
A storage device employing a flash memory as defined in Claim 8, wherein said storage capacities of said data memory area and said substitutive memory area are variable.
Claim 10
Dependent Claim
28 words
A storage device employing a flash memory as defined in Claim 9, wherein error information of said substitutive memory areas are also retained in said error memory areas.
Claim 11
Dependent Claim
33 words
A storage device employing a flash memory, comprising an electrical interface which is identical to that of a magnetic disk, and which accepts electric signals identical to those for operating said magnetic disk.
Claim 12
Dependent Claim
41 words
A storage device employing a flash memory as defined in Claim 11, wherein said electrical interface includes: acceptance means for accepting external instructions for said magnetic disk; and conversion means for converting the accepted instructions into instructions for said storage device.
Claim 13
Dependent Claim
55 words
In a storage device which employs a flash memory, and to which a host system is connected; the improvement therein comprising the fact that a block size which is a rewriting unit of said flash memory is the same as a sector size which is a processing unit of a file of said host system.
Claim 14
Dependent Claim
28 words
A storage device employing a flash memory as defined in Claim 2, wherein said substitutive memory area is formed as a predetermined part of said data memory area.
Claim 15
Dependent Claim
139 words
A storage device employing a flash memory as defined in Claim 1, wherein: said physical areas are physical sectors; said physical area identification information are physical sector identification information; said logical area is a logical sector; said logical area identification information is logical sector identification information; said logical area conversion means is logical sector conversion means supplied with said logical sector identification information in an operation of writing data, for converting said logical sector identification information into the physical sector identification information in the case of writing said data into the same logical sector as that having already recorded data therein, said physical sector identification information being different from that of the last conversion; and said memory controller receives the different physical sector identification information resulting from the current conversion, and writes said data to-be-written into the physical sector.
Claim 16
Dependent Claim
111 words
A storage device employing a flash memory as defined in Claim 15, further comprising: physical sector reference means for registering therein the logical sector identification information which correspond to said physical sectors; and logical sector reference means for registering therein said physical sector identification information which correspond to the logical sectors; said logical sector conversion means converting the logical sector into the physical sector corresponding thereto in a data reading operation in view of said physical sector reference means, and deciding if said physical sector is used, in the data writing operation in view of said logical sector reference means so as to write said data into the unused physical sector.
Claim 17
Dependent Claim
36 words
A storage device employing a flash memory as defined in Claim 15, further comprising: number of erase operations reference means for storing a number of erase operations for every erasing unit of said flash memory therein.
Claim 18
Dependent Claim
109 words
A storage device employing a flash memory as defined in Claim 17, further comprising: number of erase operations management means for checking said number of erase operations of the erasing unit which includes said physical sector, in view of said number of erase operations reference means each time the data of said physical sector is rewritten, and for replacing said data with data of the erasing unit of smaller number of erase operations, each time the checked number of erase operations reaches a prescribed value which is set so that said number of erase operations may become smaller than a guaranteed rewrite number of times of said flash memory.
Claim 19
Dependent Claim
62 words
A storage device employing a flash memory as defined in Claim 15, further comprising: status reference means for indicating either of a status in which said storage area is filled up with written data and a status in which no data is writable due to deterioration of said storage area, for said storage area of each erasing unit of said flash memory.
Claim 20
Dependent Claim
61 words
A storage device employing a flash memory as defined in Claim 15, further comprising: means for storing therein write sector pointers indicative of said physical sectors into which data are to be written in the write operations; said logical sector conversion means converting said logical sector identification information into said physical sector identification information in view of the write sector pointer.
Claim 21
Dependent Claim
78 words
A storage device employing a flash memory as defined in Claim 16, further comprising: control means; said physical sector reference means being nonvolatile storage means; said logical sector reference means being volatile storage means; said control means operating at initialization of said storage device to originate the contents of said logical sector reference means from those of said physical sector reference means being said nonvolatile storage means, and to register the originated contents in said volatile storage means.
Claim 22
Dependent Claim
56 words
A storage device employing a flash memory as defined in Claim 15, further comprising: first storage means operating when one of a plurality of physical sectors included in a smallest erasing unit of said flash memory is to be erased, for temporarily saving data of any other physical sector stored in the same smallest erasing unit.
Claim 23
Dependent Claim
36 words
A storage device employing a flash memory as defined in Claim 22, further comprising: second storage means for temporarily storing the data to-be-written therein; said second storage means being used also as said first storage means.
Claim 24
Dependent Claim
78 words
A flash memory chip, comprising: a plurality of storage areas each of which stores data and management information therein, said management information corresponding to a smallest erasing unit of said flash memory chip; and acceptance means for accepting an instruction with which any of said storage areas is selected; said each storage area having the same address as an address for accessing the corresponding smallest erasing unit, so that said management information is selected by the selecting instruction.
Claim 25
Dependent Claim
59 words
A flash memory chip, comprising: at least one area which stores data therein; a buffer area into which external data of at least one sector to be written into the data storage area is latched; and transfer means for transferring the data latched in said buffer area, to said data storage area so as to write said data thereinto.
Claim 26
Dependent Claim
60 words
A flash memory chip, comprising: at least one area which stores data therein; a buffer area into which data of at least one sector is latched; and transfer means for transferring the data of the data storage area to said buffer area in sector unit, and for delivering the data transferred to said buffer area, outside said flash memory chip.
References Cited (Backward Citations)
No citation records indexed.
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