Patent ID: 6076161
Filing Date: 2000-06-13
Classification: G06F

Abstract:
A microcontroller comprising:a mode indicator for indicating one of a plurality of operating modes the microcontroller is to assume upon start-up or reset;a program memory for storing a plurality of program code sets including a first program code set, each of the plurality of program code sets corresponding to one of the plurality of operating modes;a central processing unit (CPU) for generating a program memory default start address in the first CPU instruction-fetch cycle after start-up or reset, the program memory default start address being equal to the start address of the first program code set; anda logic circuit for detecting the operating mode indicated by the mode indicator upon start-up or reset, and if the indicated operating mode corresponds to the first program code set, then an instruction located at the program memory default start address is provided to the CPU for execution, but if the indicated operating mode corresponds to a program code set other than the first program code set, then the logic circuit prevents the instruction located at the program memory default start address from being provided to the CPU and instead the logic circuit provides a surrogate instruction to the CPU for causing the CPU to branch to the start address of said program code set other than the first program code set.