#define PAOUT (volatile unsigned char *) 0xFFFFFFF1
//needs change to be PBOUT -> 0xFFFFFFF.
#define PBIN (volatile unsigned char *) 0xFFFFFFF3

//set both inputs to 1 because start unpressed.
#define PBDIR (volatile unsigned char *) 0xFFFFFFF5
#define CNTM (volatile unsigned int *) 0xFFFFFFD0
#define CTCON (volatile unsigned char *) 0xFFFFFFD8
#define CTSTAT (volatile unsigned char *) 0xFFFFFFD9
#define IVECT (volatile unsigned int *) (0x20)

interrupt void intserv();
unsigned char digit = 0; /* Digit to be displayed, init to 0. */

int main() {

	*PBDIR = 0x00; /* Set Port B direction to input */
	*CTCON = 0x02; /* Stop Timer */
	*CTSTAT = 0x0; /* Clear “reached 0” flag */
	 *CNTM = 100000000; /* Initialize Timer */
	 *IVECT = (unsigned int *) &intserv; /* Set interrupt vector */
	asm(“MoveControl PSR,#0x40”); /* CPU responds to IRQ */
	*CTCON = 0x11; /* Enable Timer interrupts & start counting */
	 *PBOUT = 0x00; /* Display 0 */

    while (1) { //our actual program, setup already completed.

		 while ((*PBIN & 0x2) != 0); /* Wait until E SW is pressed */
		 while ((*PBIN & 0x2) == 0); /* Wait until E SW is released */

	 	 // bitwise AND &, good way to implement don't cares.
		 //handles the press/depress for E switch
		 //DO THE COUNTING.
		 *PBOUT = (digit << 4); /* Update Port B */
		 /* We can also put “*CTCON &= 0xEF;” before and “*CTCON |= 0x10;”
		 * after the last statement, to make sure that intserv() is not
		 * interfering with main() accessing shared digit/led/PAOUT */

		 while((*PBIN & 0x1) != 0);
		 while(*PBIN & 0x1) == 0));

		 *PBOUT = (0 << 4)

 	}
 exit(0);
}

interrupt void intserv() {
    *CTSTAT = 0x0; 			    /* Clear “reached 0” flag */
digit = (digit + 1)%10; 		/* Increment digit */
    *PBOUT = ((digit << 4));    /* Update Port B */
}