Patent ID: 6646917
Filing Date: 2003-11-11
Classification: G06F

Abstract:
A storage device, comprising:a nonvolatile semiconductor memory having data erased in a unit of block that is formed of a plurality of pages and written in a unit of page for a page having data erased therefrom; and a control portion controlling said nonvolatile semiconductor memory; said nonvolatile semiconductor memory including a user block storing user data, an alternate block reserved for substitution, a conversion table storing a physical address of said user block corresponding to a logical address, and an alternate table storing a physical address of said alternate block, and said control portion, when referring to said conversion table for writing the user data to a page within the user block, if the relevant page has data written therein, referring to said alternate table and writing the user data to a page within said alternate block, so that said alternate block becomes a new user block, while the original user block becomes a new alternate block.