Power Failure Reset
The 80C320 is equipped with an automatic power failure reset. This means that if the operating voltage drops below Vrst (see
chip spec sheet.) , the microcontroller will automatically enter a reset mode. The chip will remain in reset mode until normal operating voltage is restored. This reset is performed automatically requiring no special action on the part of the software or of the user.
Interesting Fact: This feature is important. A normal 8051, without such a feature, continues to run "normally" as power dips below the minimum. However, the 8051 may begin to execute bogus instructions and/or starts writing/reading incorrect values to and from memory locations. The power failure reset feature on the 80320 prevents a low power condition from causing strange and unexpected program behavior.