Reset & Interrupt Vectors

RESET Vector

At RESET the program counter is cleared, resulting in all 0s. This allows program memory address 0h to be the location of the first instruction executed after a RESET condition.

Interrupt Vector

When an interrupt occurs program control is transferred to address 04h. The Interrupt Training Section provides a complete description of the interrupt process

Return Stack

A sixteen entry 15-bit wide hardware return stack stores the Program Counter in the event of either an interrupt or call to a subroutine. The return stack works on a last-in-first-out basis.
Upon executing a return instruction ( RETFIE or RETURN) the top element of the stack is removed from the stack and placed into the program counter.