Method and apparatus for dynamically creating conversion tables to access a semiconductor memory device
First Claim
1. A semiconductor memory device comprising:
- a nonvolatile memory which is addressable by sectors;
an interface for receiving an access request from a host computer system to access data from said nonvolatile memory;
a volatile memory;
means for creating a first table in response to an access request from said host computer system representing logical-to-physical address conversion information for a page having a plurality of sectors stored in said volatile memory for converting a logical sector address into a physical sector address;
and means for creating a second table in response to an access request from said host computer system representing logical-to-physical address conversion information for a unit having a plurality of pages stored in said volatile memory for converting a logical page number into a physical page number.
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Abstract
An improved external semiconductor memory device having a work memory for storing logical address-physical address conversion information. According to one embodiment of the present invention, a semiconductor memory device, which is connected to a host computer system and can be addressed as predetermined sector units, comprises: (a) a data storage having a nonvolatile memory that can be electrically rewritten; (b) an interface connected to the host computer system for receiving an access request; (c) volatile work memory; (d) first table preparating means for preparing a first table in the volatile work memory, by the page which consists of a plurality of sectors, for converting the requested logical sector address into a physical sector address among a physical memory space of the data storage; (e) second table preparation means for preparing a second table in the volatile work memory, by the unit which consists of a plurality of pages, for converting a logical page numbers addressed by the access request into a physical page numbers among a physical memory space of the data storage; (f) second access control means for, in response to an access request from the host computer system, referring to the second table for a unit to which the designated logical sector address belongs in order to acquire a corresponding physical page number; (g) first access control means for, in response to an access request from the host computer system, referring to the first table for a physical page to which the designated logical sector address belongs in order to acquire a corresponding physical sector address; and (h) data access means for accessing the data storage in accordance with the acquired physical sector address.
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Citations
12 Claims
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1. A semiconductor memory device comprising:
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a nonvolatile memory which is addressable by sectors; an interface for receiving an access request from a host computer system to access data from said nonvolatile memory; a volatile memory; means for creating a first table in response to an access request from said host computer system representing logical-to-physical address conversion information for a page having a plurality of sectors stored in said volatile memory for converting a logical sector address into a physical sector address; and means for creating a second table in response to an access request from said host computer system representing logical-to-physical address conversion information for a unit having a plurality of pages stored in said volatile memory for converting a logical page number into a physical page number. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for accessing a semiconductor memory device having a nonvolatile memory which is addressable by sectors comprising the steps of:
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(a) in response to an access request from a host computer, creating a first table representing logical-to-physical address conversion information for a page having a plurality of sectors for converting a logical sector address into a physical sector address; (b) in response to the access request from said host computer, creating a second table representing logical-to-physical address conversion information for a unit having a plurality of pages for converting a logical page number into a physical page number; (c) in response to the access request from said host computer system, acquiring the physical page number corresponding to the requested logical sector from said second table for said unit; (d) in response to the access request from said host computer system, acquiring the physical sector address corresponding to the requested logical sector from said first table for said page; and (e) accessing said nonvolatile memory with the acquired physical sector address. - View Dependent Claims (8, 9, 10, 11, 12)
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Specification