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. 07, 1990
Filed:
Feb. 10, 1989
Philip W Bullinger, Wichita, KS (US);
Thomas L Langford, II, Wichita, KS (US);
John W Stewart, Wichita, KS (US);
NCR Corporation, Dayton, OH (US);
Abstract
For LSI/VLSI integrated circuits which inherently have an address decoder and a data bus, a scan testing method and apparatus is presented which does not require additional pin connections to be dedicated for scan test implementation. Counter to the Joint Test Action Group approach, the present invention uses additional registers, multiplexers, and decoders in conjunction with the existing buses to provide test access to otherwise embedded layers of logic circuitry, without the addition of a single pin connection to a integrated circuit chip package. Further, since this test method and apparatus uses the data bus and registers just as the rest of the chip, slow and complex d.c. level shifting equipment is not required.