// Preface 6812 C programs// Jonathan W. Valvano// This software accompanies the book,// Embedded Microcomputer Systems: Real Time Interfacing// published by Brooks Cole, 1999// Program P.2 (Preface)// MC68HC812A4/MC68HC912B32#define PORTA *(char volatile*)(0x0000)char data;void main(void){    while(1){      data=PORTA;}}#pragma abs_address:0xfffevoid (*reset_vector[])() = { _start };#pragma end_abs_address