Program memory space expansion for particular processor instructions
US7509478B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Sep 10, 2007 |
| Grant date | Mar 24, 2009 |
| Priority date | — |
| Expiry date | Nov 27, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F9/3824
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A system efficiently expands program memory without extensively modifying the remaining microcontroller architecture. An address bus of N+M bits addresses 2N memory 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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.