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. 11, 2007
Filed:
Jul. 23, 2004
Stephen H. Chan, Los Altos Hills, CA (US);
Stephen H. Chan, Los Altos Hills, CA (US);
ZiLOG, Inc., San Jose, CA (US);
Abstract
A system efficiently expands program memory without extensively modifying the remaining microcontroller architecture. An address bus of N+M bits addresses 2memory locations in a regular portion of program memory and additional memory locations in an expanded portion. An N-bit program counter increments through instructions stored only in the regular portion. Constants are stored in both the regular and expanded portions. An M-bit page-designator is prepended to an N-bit operand to generate a memory address of N+M bits. Program memory is expanded only when a load instruction retrieves constants from program memory. The page-designator is toggled when an N-bit operand rolls over upon incrementing by the load instruction. A block of constants straddling the boundary between the regular and expanded portions can be retrieved from program memory by executing only the load instruction. When program instructions are executed that do not retrieve constants, a fixed page-designator designates the regular portion.