LIST P=16F84A
;************************************************* ************************************************** *****$
; Include An Additional File In The Program .
#INCLUDE "P16F84A.INC"
;************************************************* ************************************************** *****$
; Configuration Register Bits .
__CONFIG _CP_OFF & _WDT_OFF & _PWRTE_ON & _XT_OSC
;************************************************* ************************************************** *****$
; Reset Vector .
org 0x00
GOTO Start
org 0x04
banksel PORTA
bsf PORTA,1
retfie
Start
Banksel TRISB
movlw b'11111111'
movwf TRISB
BANKSEL TRISA
clrf TRISA
BANKSEL PORTA
clrf PORTA
BSF OPTION_REG, INTEDG ; interrupt on positive
BCF INTCON, INTF ; clear interrupt flag
BSF INTCON, INTE ; mask for external interrupts
BSF INTCON, GIE ; enable interrupts
LOOP GOTO LOOP
END