*
*  Lab2
*
*  Purpose: Turn the lights 1/4 second red, 1/4 second green,
*           1/4 second off, and repeat
*
*  Author: Heather D. Pfeiffer
*
* Setup some useful labels
EEPROM		equ	$f800	
RESET		equ	$fffe
redlght		equ     $ff	
greenlght	equ	$f0	
nolght		equ	0
motors		equ	$1004

* Program code for playing with lights
	org	EEPROM
start
	
* First turn on the red lights for 1/4 of a second
	ldx	#49999		* initialize the countdown counter
	ldaa	#redlght	* load up red lights
redlp	staa	motors		* turn lights on
	dex	
	bne	redlp		* 10 cycles in loop * 49999 = 499,990 cycles
* 4 cycles from above loop should not count;  first store, so 499,986
	
	nop		
	brn	redlp

* Second turn on the green lights for 1/4 of a second
	ldx	#49999		* initialize the countdown counter
	ldaa	#greenlght	* load up green lights
* 10 cycles from above padding + 4 next store instruction
*    gives 499,986 + 14 = 500,000 cycles for red lights
	
grlp	staa	motors		* turn lights on
	dex		
	bne	grlp		* 10 cycles in loop * 49999 = 499,990 cycles
* 4 cycles from above loop should not count;  first store, so 499,986
	
	nop	
	brn	grlp

* Last turn on no lights for 1/4 of a second
	ldx	#49999		* initialize the countdown counter
	ldaa	#nolght		* load up no lights
* 10 cycles from above padding + 4 next store instruction
*    gives 499,986 + 14 = 500,000 cycles for green lights
	
nolp	staa	motors		* turn lights on
	dex		
	bne	nolp		* 10 cycles in loop * 49999 = 499,990 cycles
* 4 cycles from above loop should not count;  first store, so 499,986

	nop	
	bra	start
* 5 cycles here + 5 cycles at start + 4 for store = 14 cycles
*    gives 499,986 + 14 = 500,000 cycles for no lights

* Setup the RESET vector
	org	RESET
	fdb	start