Reset is the highest priority interrupt and is used to initialize the CPU to a known state. The reset interrupt is unique in a number of ways:
- cpu_resetz_i is an active-low signal and is treated asynchronously. All other interrupts are active-high signals, or activated via the instruction decoder.
- cpu_resetz_i must be held low for 4 clock cycles before it goes high again to reinitialize the CPU properly.
- cpu_resetz_i is not affected by branches or pending loads or any enable bits or any other condition applicable for processing other interrupts. The current instruction execution is aborted and the CPU registers are returned to their default state.
- Reset uses interrupt semantics, that is, loading of the IST table entry; however, it is not required to issue a BIRP instruction to exit reset processing.