I've think I've found the problem. There must be some incompatability with my fast machine(a 1900mhz), as it reads the chips empty. I tested it on a dos p133 machine, and it appears to have been programmed with both code protect bits set, on rs osc. The program code is all 0000. So this machine seems to have read it properly, and would explain why the other machine can't rewrite - code protection on nothing. So I've wasted aus $25 on the pic16f876, but I've learned not to use this machine to program it. Btw, Picall doesn't need to be registered for picall hardware. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.