MEGAWIN

MLC0xxB Series Technical Summary

5

Program Counter (PC)

The 16-bit program counter register provides the addresses, which step the micro-controller through

sequential program instructions. Each time the micro-controller fetches an instruction from program

memory, the lower byte of the program counter (PCL) is placed on the low-order 8 bits of the address

bus and the higher byte of the program counter (PCH) is placed on the high-order 8 bits. The counter

is incremented each time an instruction or data is fetched from program memory.

Stack Pointer (S)

The stack pointer is an 8-bit register, which is used to control the addressing of the variable-length

stack. The stack pointer is automatically incremented and decremented under control of the

micro-controller to perform stack manipulations under direction of either the program or interrupts

(/NMI or /IRQ). The stack allows simple implementation of nested subroutines and multiple level

interrupts. The stack pointer is initialized by the user’s software.