Patent ID: 7864580
Filing Date: 2011-01-04
Classification: G11C

Abstract:
1. A method of managing a defective column in a nonvolatile semiconductor storage system, comprising: supplying power to a nonvolatile semiconductor storage system including a nonvolatile semiconductor memory to start up the nonvolatile semiconductor memory; detecting the supply of power and reading defective column address data held in a memory cell array of the nonvolatile semiconductor memory to hold the read address data as defective column separation data in a holding circuit; initializing a data latch circuit for holding data in units of page to set the data latch circuit at first data; inputting a defective column information output command from a memory controller to the nonvolatile semiconductor memory to start an output operation of the defective column information in the nonvolatile semiconductor memory; reading data for one column via a data line; judging whether the column of the read data is a normal column or a defective column; updating a defective column management table when the column is a defective column; judging, when the column is not a defective column, whether or not the column address is the final column address, and judging, when the column is a defective column, after updating the defective column management table, whether or not the column address is the final column address; incrementing the column address when the column address is not the final column address, and reading data for a next one column in sequence and judging whether or not the column address is the final column address; and ending the defective column information output operation at a time when the column address is judged to be the final column address.