Data processor having operating modes selected by at least one mask option bit and method therefor
US5598569A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 17, 1994 |
| Grant date | Jan 28, 1997 |
| Priority date | — |
| Expiry date | Oct 17, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C16/20
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.