Hello Toni

The purpose:
to flash an led once a second--> temporization of 500 ms
By using the TMR0 and the prescaler configured in 256

calculation:
if my PIC run 4 Mhz
An interruption--> all 256 us

prescaler configured in 256
An interruption--> all 256*256=65536 us

I must use a interrupt routine
500000/65536=7.63-->8X


sorry for my poor englich