MEGAWIN

MLC510B 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 when 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 by the 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.