; TUTA4.ASM
; using	aliases, bit names and conditional loops
        list	p=p16f84a
        radix	hex
	include "p16f84a.inc"

; high speed >4MHz OSC
; disable watchdog timer
	__CONFIG _HS_OSC & _WDT_OFF       

#DEFINE	PAGE0 BCF STATUS,5
#DEFINE	PAGE1 BSF STATUS,5

COUNT	EQU 0x0C	; Counter storage
NCOUNT	EQU 0x0D	; Count Down storage register
MCOUNT	EQU 0x0E	; Count Down storage register
OCOUNT	EQU 0x0F	; Count Down storage register
W	EQU 0		; Working register flag
F	EQU 1		; File register flag
C	EQU 0		; Carry flag

	ORG 0		 ; Reset vector
	CALL 5		 ; CALL start of program
       	ORG 4		 ; Interrupt vector
	CALL 5		 ; CALL start of program
       	ORG 5		 ; Start of program memory

       	CLRF PORTA	 ; clear Port A data register
       	CLRF PORTB	 ; clear Port B data register

       	PAGE1		 ; PAGE1

       	CLRF TRISA	 ; set all Port A as output (clear direction reg)
       	CLRF TRISB	 ; set all Port B as output (clear direction reg)

       	PAGE0		 ; PAGE0


; illuminate LEDs left to right
LOOP	BSF PORTA,2
	CALL PAUSE 
	BCF PORTA,2
	BSF PORTA,3
	CALL PAUSE 
	BCF PORTA,3
	BSF PORTB,0
	CALL PAUSE
	BCF PORTB,0
	BSF PORTB,1
	CALL PAUSE
	BCF PORTB,1
	BSF PORTB,2
	CALL PAUSE
	BCF PORTB,2
	BSF PORTB,3
	CALL PAUSE
	BCF PORTB,3
	BSF PORTA,1
	CALL PAUSE
	BCF PORTA,1
	BSF PORTA,0
	CALL PAUSE
	BCF PORTA,0
	BSF PORTB,7
	CALL PAUSE
	BCF PORTB,7
	BSF PORTB,6
	CALL PAUSE
	BCF PORTB,6
	BSF PORTB,5
	CALL PAUSE
	BCF PORTB,5
	BSF PORTB,4
	CALL PAUSE
	BCF PORTB,4
        GOTO LOOP

PAUSE	MOVLW	0xFF 
	MOVWF	MCOUNT
LOADN	MOVLW	0xFF
	MOVWF	NCOUNT
DECO	NOP
	NOP
	NOP
	NOP
	NOP
	DECFSZ	OCOUNT,F
	GOTO	DECO
	DECFSZ	MCOUNT,F
	GOTO	LOADN
	RETURN
END