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:
Feb. 01, 1983
Filed:
May. 06, 1981
David B Schuck, Escondido, CA (US);
NCR Corporation, Dayton, OH (US);
Abstract
A data processing system that has a plurality of subsystems connected to a system bus includes diagnostic circuitry for isolating a fault at one of the subsystems. The diagnostic circuitry includes a multiplexer at the output gates of each subsystem to the system bus and diagnostic selection circuitry at a bus controller that provides a select signal to each multiplexer. When selected, the multiplexer is connected to pass a 'high' logic level signal to an associated bit line of the system bus. When a bit line of the system bus is 'stuck high,' because of a fault at the output of one of the subsystems, the diagnostic circuitry selectively connects each subsystem to the bit line of the system bus in order to provide a 'high' logic level signal to that bit line. A test interface and A/D converter are connected to the bit line, and if a voltage level change is detected after a subsystem is connected, the connected subsystem is not the one having the fault. If no voltage level change is detected, it is known that that subsystem is the faulty one.