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:
Aug. 18, 1992
Filed:
Jan. 31, 1990
Sunao Araki, Kawasaki, JP;
Fujitsu Limited, Kawasaki, JP;
Abstract
A semiconductor memory device is provided with a memory cell array having a plurality of memory cells formed by a mask ROM. The memory cell array has a data area in which stored data of n bits is stored and a parity area in which a one-bit parity code corresponding to the stored data is stored. A control circuit supplies the memory cell array with an address and reads out the stored data and the one-bit parity code designated by the address. A parity check circuit determines whether the data read out from the memory cell array has a bit error and generates a correction bit responsive thereto. A memory stores predetermined indicating data indicating which of the n bits of the stored data is defective. A data correction circuit then corrects one of the n bits of the data indicated by the predetermined indicating data in response to the correction bit generated by the parity check circuit.