list        p=16F887, r=dec, w=-302
        include     <P16F887.INC>
        __config    _CONFIG1,_LVP_OFF & _FCMEN_OFF & _IESO_OFF & _BOR_OFF & _PWRTE_ON & _WDT_OFF & _INTOSCIO
        __config    _CONFIG2,_WRT_HALF & _BOR21V

#define     LED0        PORTD,0

                cblock          0x20
                                COUNT1
                                COUNT2
                endc

        org     0x000       ;reset vector
        goto        START

START       clrf        PORTA       ;init ports
        clrf        PORTB
        clrf        PORTC
        clrf        PORTD
        clrf        PORTE
        banksel     ANSEL       ;bank 3
        movlw       b'00000000' ;all ports digital I/O
        movwf       ANSEL
        movwf       ANSELH
        banksel     TRISA       ;bank 1
        movlw       b'00000000' ;all ports output
        movwf       TRISA
        movwf       TRISB
        movwf       TRISC
        movwf       TRISD
        movwf       TRISE
                movlw           b'11010111'     ;tmr0 clock source = instruction clock
                movwf           OPTION_REG      ;1:256 prescale
        banksel     0x00        ;bank 0

                clrf            TMR0            ;init tmr0
                bcf             INTCON,T0IF     ;clear tmr0 interrupt flag
        btfss           INTCON,T0IF     ;is tmr0 interrupt flag high?
                goto            $-1             ;no, check again
                movlw           b'00000001'     ;toggle LED0
                xorwf           PORTD,F
                goto            $-6             ;do forever

        end                             ;end of file