hi All, For the 16F87x and probably for other PICs that can write in their own program memory, the writing to program-memory behaves different then the writing to the data-memory: When writing to program-memory, the processor is stopped until the writing is done (4..8 msec). I guess, but I'm not sure, and I don't know if there are any exceptions: All pheripherals (timers, usart, interrupts, etc. ) are continuing their normal job. Is this true ?? thanks, Stef Mientki -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.