The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 05, 1999
Filed:
Apr. 15, 1997
Tohru Sakakura, Yamato, JP;
Yoshinori Sakaue, Sagamihara, JP;
International Business Machines Corporation, Armonk, NY (US);
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.