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. 14, 1993
Filed:
Sep. 10, 1991
Derk J Wassink, Eindhoven, NL;
U.S. Philips Corporation, New York, NY (US);
Abstract
Microprocessor-controlled apparatus, for example, a car radio whose microprocessor (5) is one-time programmable by the manufacturer of the apparatus. An external non-volatile memory (7) comprises a security variable (VAR) indicating whether the protection means is operational. In addition to a security code (SC), an arbitrary code series (KEY) of, for example, 20 bits is stored in the internal memory (51) of the microprocessor. Unauthorized disabling of the protection means by external interrogation of the non-volatile memory is only possible by assigning a value which corresponds to the code series to the security variable. However, the code series is inaccessible and can only be traced with great difficulty by means of trial and error methods.