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. 12, 1995
Filed:
Dec. 18, 1992
David M Purdham, Brooklyn Park, MN (US);
David C Johnson, Roseville, MN (US);
Unisys Corporation, Blue Bell, PA (US);
Abstract
A method of and apparatus for continuously checking a CMOS SRAM memory system. Each memory cell has a bistable circuit for retaining the state of the cell, along with a totally redundant bistable circuit. Added circuitry provides continuous comparing of the binary state of the bistable circuit and the redundant bistable circuit within the memory cell. This testing is performed at a low level within the memory cell eliminating the power dissipation and size requirements associated with additional drivers. An error line is shared amongst a number of memory cells. By continuously monitoring in this manner, the time of failure as well as the fact of failure can be determined.