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. 17, 1996
Filed:
May. 15, 1995
Masayuki Daito, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
A microprocessor is provided with a self-diagnostic test function. The microprocessor comprises an input circuit for inputting at least a macro instruction and information necessary for self-diagnostic testing stored in an external memory; a decoder for decoding the inputted macro instruction; a micro instruction ROM for storing micro instructions; an incrementer for generating an incremented address by incrementing the address of the received address of the micro instruction ROM by 1. The microprocessor also includes an external test mode setting circuit (ETMSU) that inputs an incremented address and information necessary for self-diagnostic testing, and that outputs an incremented address when the microprocessor is operating in normal mode. In accordance with micro instructions outputted by the micro instruction ROM, the ETMSU outputs either an incremented address or information necessary for self-diagnostic testing when the microprocessor is operating in self-diagnostic testing mode. The microprocessor also includes a selector for selecting in accordance with micro instructions any one of the decoder output, an address of the micro instruction ROM designated by the micro instructions, or the output of the external test mode setting circuit. The microprocessor operates as an ALU when operating in normal mode, and when operating in self-diagnostic testing mode, provides data to diagnose whether or not it is defective.