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:
May. 07, 1991
Filed:
May. 02, 1988
Ajay J Padgaonkar, Phoenix, AZ (US);
Sumit K Mitra, Tempe, AZ (US);
Other;
Abstract
The processor executes programs from an internal EEPROM or from an external source. The EEPROM can be read either by a special operating (test) mode of the processor or by an instruction executing under normal operating mode from the EEPROM or from an external source. Similarly, the EEPROM can be programmed (written) either by a special operating mode or by under a normal operating mode instruction. The read and write circuits for the EEPROM are controlled to provide two levels of security against piracy of programmed information. In the first level, access is prevented for the read and write test modes and also for the read and write normal operating instructions if the instructions originate from an external source. In the second level, program execution from external source is also disabled.