Hello! I'm working with 16C505. I've read the last memory location (for eg. movlw 0x54), which I'll reprogram after erase (I'm working with JW eprom version). I'm wondering if there must be the instruction : movwf OSCCAL at the beginnig of the programme, if I want to work at exacly 4MHz (internal oscillator). Thanks Andrej Vuga _______________________________________________________________________ Free Unlimited Internet Access! Try it now! http://www.zdnet.com/downloads/altavista/index.html _______________________________________________________________________ -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.