EP0522780A2
Expired / Lapsed
EP
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Control method for a computer memory device
Assignee: International Business Machines Corp
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Filing: 1992-07-01
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Granted: —
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Expires: 2012-07-01
Abstract
Abstract To provide an external storage system using a semiconductor memory in which the data reading and writing between the host CPU can be processed faster than the conventional magnetic disk, and only a particular sector is not frequently written and erased so that the whole memory is effectively used over a long period of time, an address control scheme is introduced in which flexibility is given to the address relation between the host CPU and the external storage and the physical address of the semiconductor memory is not one-sidedly determined by the logical address possessed by the command of the host CPU.
Inventors
- 👤 Yoshinori Sakaue
- 👤 Hideto Niijima
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-25 10:12
CPC Classifications
G; G06; G06F; G06F3/00; G06F3/06; G06F3/0601; G06F12/00; G06F12/02; G06F12/08; G06F12/0802; G06F12/0866; G06F12/12; G06F12/121; G06F12/122; G06F2212/00; G06F2212/20; G06F2212/202; G06F2212/2022; G06F2212/31; G06F2212/312; G06F3/0628; G06F3/0662; G06F3/0664; G11; G11C; G11C16/00; G11C16/02; G11C16/06; G11C16/10; G11C16/102; G11C16/34; G11C16/349
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
209 words
A method for controlling a storage system comprising a semiconductor memory of the flash memory type, the memory comprising a plurality of memory blocks each including at least one sector, and a control device for controlling said memory blocks, said storage system being connected to a host processor through a bus for transferring data and a command, the metod comprising; selecting a memory block for which data is to be written or erased on the basis of a memory managing table which has recorded therein the number of times each memory block was erased and the statuses of each memory block and each sector; converting the logical address included in said command of said host processor to a physical address indicating the sector in a particular memory block by reference to an address conversion table; responding to said command to perform a process of data writing or reading to the corresponding sector or memory block erasure; sequentially recording or updating in said memory managing table the status changes of each sector and memory block resulting from the processes; and storing or updating in the address conversion table the relationships between the physical addresses and the logical addresses of the memory block and sector on which said processes were performed.
Claim 2
Dependent Claim
94 words
A method as claimed in Claim 1 comprising accepting the command of said host processor by interruption, and if said command is a data read command, responding thereto to perform the process of reading the data from the corresponding sector of said memory block corresponding to the logical address of said command, and if said command is a write or erase command, holding such command and data in a buffer and executing said write or erase process to said selected memory block or sector when there is no interrupt command from said host processor.
Claim 3
Dependent Claim
57 words
A method as claimed in Claim 1 or Claim 2, comprising selecting a particular memory block of said memory blocks with priority as an object to be erased if the number of times said particular memory block was erased is smaller than the largest number of times any other memory block was erased by a predetermined value.
Claim 4
Independent Claim
60 words
A method as claimed in any of Claims 1 to 3 comprising selecting based on the record of said block control means, a memory block having free sectors for copying the data in the valid sectors of said memory block to be erased, and copying said data into said selected memory block prior to the erasure of said memory block.
Claim 5
Independent Claim
41 words
A method as claimed in any preceding claim comprising executing the process of reading the data from a corresponding sector of said memory block and said write or erase process to said memory block or sector by a time sharing process.
Claim 6
Dependent Claim
90 words
A method as claimed in Claim 5 comprising responding to a sector write command from said host processor by writing said data into a free sector of said selected memory block, and if the logical address of said sector write command is equal to the logical address of the valid sector which has already been written, rewriting the record of the status with respect to said valid sector of the memory management table to be invalid, and writing the physical address of said free sector into said address translation table.
Claim 7
Independent Claim
46 words
A method as claimed in any preceding claim comprising saving the record of the number of times a memory block has been erased prior to each erasure of said memory block, and writing said record back to said memory block after erasure of said memory block.
Claim 8
Independent Claim
49 words
A method as claimed in any preceding claim comprising updating the record of said memory management table on the erasure of a memory block by comparison of the new file allocation information held by said host processor with the old file allocation information held in the external storage system.
Claim 9
Dependent Claim
112 words
An external storage system connected to a host processor through a host bus for transferring data and a command comprising: a semiconductor memory consisting of a flash memory and comprised of a plurality of memory blocks each including at least one sector, address conversion means for converting the logical address received from said host processor to the physical address of a particular sector, block managing means for recording the status of each memory block and sector, and a command processing section which uses the record of said block managing means to control the reading or writing of data to each sector of said semiconductor memory, or the erasing of a memory block.
Claim 10
Dependent Claim
74 words
An external storage system as claimed in Claim 9 wherein said control section includes a data writing section, data reading section and block erasing section for executing a data writing, reading or erasing process to the corresponding memory block or sector of said semiconductor memory on the basis of said command processing section, and a sector copying section for copying the valid sectors of the memory block to be erased to another memory block.
Claim 11
Dependent Claim
90 words
An external storage system as claimed in Claim 9 wherein said control section includes: a command processing section, data writing section, data reading section, block erasing section, and a sector copying section used for copying the valid sectors of a memory block to be erased to another memory block which consists of a microprocessor, a block managing table, address conversion table and a buffer which are formed on RAM, and a sector managing table constituting said block managing means along with said block managing table provided on each memory block.
Claim 12
Dependent Claim
67 words
An external storage system as claimed in Claim 9 wherein said control section includes: a command processing section formed on a host processor, a block managing table and an address conversion table formed on the RAM of the main memory, a memory controller including a buffer, and a sector managing table constituting said block managing means along with said block managing table provided on each memory block.
Claim 13
Dependent Claim
184 words
A computer system comprising a host processor, an external storage system including a semiconductor memory which consists of a flash memory and comprises a plurality of memory blocks each including at least one sector, and a host bus for transferring data and a command between said external storage system and said host processor, characterized by: control means which uses an address conversion means for converting the address from said host processor to the physical address of a particular sector and block managing means for recording the status of each memory block and each sector therein to control the data reading and writing to each sector of said semiconductor memory and the erasure of a memory block in response to said command, said control means having means which are responsive to the command from said host processor for executing the process of data writing or reading to the corresponding sector of said semiconductor memory or of erasing a memory block, and for updating the record of the status of each memory block and each sector of said block managing means in connection with such process.
Claim 14
Dependent Claim
64 words
A computer system as claimed in Claim 13 having display means connected to the host processor and the external storage system through the host bus, wherein said control means outputs to said display means that said semiconductor memory is to be replaced when there is no free sector in any of said memory blocks and there is also no memory block to be erased.
Claim 15
Dependent Claim
85 words
A computer system as claimed in claim 13 having interactive display means connected to the host processor and the external storage system through the host bus, wherein said control means receives information as to whether or not file recovery is required from a user by an interaction via said display means, and if file recovery is required, refers to the file allocation information held by the computer system and displays the content of the file, and obtains the user's confirmation, thereby performing the file recovery.
Claim 16
Dependent Claim
51 words
A semiconductor memory consisting of a flash memory and comprising a plurality of memory blocks each including at least one sector, wherein a particular region is provided in each said memory block for storing the record representing the number of times said memory block was erased and status of each sector.
Claim 17
Dependent Claim
37 words
A semiconductor memory as claimed in Claim 16 wherein one said particular region is provided for each memory block as a sector managing table for recording the status of all the sectors included in each memory block.
References Cited (Backward Citations)
No citation records indexed.
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