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:
Sep. 07, 1999
Filed:
Dec. 23, 1997
Noboru Shibata, Yokohama, JP;
Hideo Kato, Kawasaki, JP;
Taira Iwase, Kawasaki, JP;
Kenji Yano, Yokohama, JP;
Kabushiki Kaisha Toshiba, Tokyo, JP;
Abstract
An address storing PROM cell array formed of a PROM having one polysilicon layer stores an address of a defective cell contained in a mask ROM used as a main memory cell array. A data storing PROM cell array formed of a PROM having one polysilicon layer stores data to be written into the defective cell. When an input address hits the address stored in the address storing PROM cell array, an address detecting circuit reads out data stored in the data storing PROM cell array instead of data of the mask ROM. When data in an address corresponding to the defective cell of the mask ROM is rewritten twice or more, a priority setting circuit permits newest data to be preferentially read out.