LIST P=16F628A
 #INCLUDE "P16F628A.INC"
 __CONFIG _INTOSC_OSC_NOCLKOUT &_CP_OFF&_WDT_OFF&_LVP_OFF& _MCLRE_OFF& _PWRTE_OFF& _BOREN_OFF

	CBLOCK	0X20
	CF
	ENDC

	ORG	0
 	GOTO	START

	ORG 4

	BCF		PIR1,CMIF
	COMF	CF,F
	BTFSS	CF,0
	BCF		PORTB,3
	BTFSC	CF,0
	BSF		PORTB,3
	RETFIE
	
START

	BCF		STATUS,RP0
	MOVLW	B'00000101'
	MOVWF	CMCON 
	BSF		STATUS,RP0	;BANK1
	BSF		PCON,OSCF
	MOVLW	B'00111110'
	MOVWF	TRISA
	MOVLW	B'00000000'
	MOVWF	TRISB
	MOVLW	B'00001000'
	MOVWF	OPTION_REG
	BSF		PIE1,CMIE
	BCF		STATUS,RP0	;BANK0
	CLRF	PORTA	
	CLRF	PORTB
	BSF		INTCON,GIE
	BSF		INTCON,PEIE

PROGRAM

	BTFSS	CMCON,7
	BCF		PORTB,0
	BTFSC	CMCON,7
	BSF		PORTB,0
	GOTO	PROGRAM
	
	END