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:
Jan. 28, 1997
Filed:
Oct. 17, 1994
Michael I Catherwood, Austin, TX (US);
George L Espinor, Austin, TX (US);
Motorola Inc., Shaumburg, IL (US);
Abstract
A data processor (20) includes a nonvolatile memory system (25) which stores not only normal program memory (31), but also mask option bits (32), within a common array (30) of nonvolatile memory cells. A control circuit (40) of the nonvolatile memory system (25) detects when a central processing unit (21) is accessing the program memory (31). In response to either an end of reset signal or a refresh request signal, the control circuit (40) copies the mask option bits (32) into a volatile mask option register (44) only when the central processing unit (21) is not accessing the program memory (31). Otherwise, the control circuit (40) holds off the access to the mask option bits (32). The mask option register (44) provides signals to various circuits (28) to control their operation. Thus, the mask option bits (32) may be stored in nonvolatile form in the same array (30) as the program memory (31), enhancing reliability and reducing integrated circuit size.