.org    $0000
    rjmp        reset

.org    INT0addr
    sbi     PORTB,0
    cbi     PORTB,0
    reti

reset:
    sbi     DDRB,0
    puti    SMCR,(1<<SM1)+(1<<SE)                       ; power-down
    puti    EICRA,(1<<ISC01)+(1<<ISC00)                 ; rising edge of INT0
    puti    EIMSK,(1<<INT0)
    sei
main_loop:
    sleep
  rjmp      main_loop