Security for digital signal processor program memory
US5014191A · kind A · utility
Inventors
Key dates
| Filing date | May 2, 1988 |
| Grant date | May 7, 1991 |
| Priority date | — |
| Expiry date | May 2, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F2221/2105
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.