One step forward, next wall. I can now program a 16f87xA, but I can't get it to run on any combination of xtal (1..20 MHz) and caps (solderless breadbord only, 22pF, 42pF) that I tried :( Note that a plain 16f877 did run on each of those combinations (with exactly the same program), and that the -A with an external oscillator runs OK. Any suggestions? Wouter van Ooijen -- ------------------------------------------- Van Ooijen Technische Informatica: www.voti.nl consultancy, development, PICmicro products -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.